外文翻譯--礦井提升機(jī)繩索的失效分析

外文資料與中文翻譯 外文資料： FAILURE ANALYSIS OF A MINE HOIST ROPE Astarte-An extensive investigation was carried out to determine the cause of the early retirement of an inservicehoist rope. The rope was retired earlier than expected because it met the criteria for removal based on the number and distribution of wire breaks. Its chemistry, strength and ductility compared favorably to standards for new ropes. Metallography revealed minor anomalies, but these appeared indiscriminately in both the good and the bad segments, and in both broken and unbroken wires. Only one item appeared to be related to the failure of wires, and this was the appearance of a construction anomaly. This anomaly, termed a dive, disrupts the construction of the strand, and may cause excessive crown wear or unusual wear patterns.The wire breaks removed from the rope were all found in the vicinity of dives. The investigation suggests that the dives are responsible for the premature retirement of the hoist rope. Published by Elsevier Science Ltd. 1. INTRODUCTION Wire ropes transmit large axial loads, and exhibit extreme flexibility. In addition, a wire rope is designed so that it can withstand some wire breaks without a loss of integrity. These characteristics make wire rope a versatile component in many systems. Wire ropes are used in many industries,with applications that include mining, offshore oil production, and towing or mooring of ships. The Albany Research Center has been studying the degradation mechanisms of wire ropes with the goal of more accurately predicting when the end of the useful life of a rope has been reached. In partnership with Henderson Mine, Albany Research Center personnel investigated a hoist rope that was retired after an unexpectedly short service life.After 9 months of service, the rope was retired because it exceeded the allowable number of broken wires per lay length 1. Two rope segments were selected for investigation. One segment was at or near the location that required retirement because of broken wires (hereafter referred to as the bad segment), and the other segment came from the dead wrap on the drum (hereafter referred to as the good segment). The two segments were analyzed for differences in construction, steel composition and processing, and mechanical properties. Since it was felt that this rope was retired prematurely, the analysis was designed to identify, and, if possible, quantify, any differences that might account for the wire breaks. Initial examination focussed on two broad questions: (1) what are the differences between the wires in the good and the bad rope segments, and (2) are there any physical or mechanical differences between broken and unbroken wires in the bad segment? 2. BACKGROUND Wire ropes are composed of wires wound into bundles called strands, which are then wound into the final rope (Fig. 1). The centermost wire of a strand, known as the king wire, provides support for the wires wrapped around it. One or more layers may be wrapped around the king wire to form the strand. The last layer of wires forms the outside of the strand, and, hence, the wires are called outside wires. The number, size and arrangement of wires in a strand, and the number of strands in a rope, determine its construction. The wires within the strand and the strand within the Fig. 1. The three basic components of a wire rope are the wire, the strand, and the core. The wire is a single, continuous length of metal that is drawn from a rod. The strand is a symmetrically arranged and helically wound assembly of wires. The core is the central member of a wire rope, about which the strands are laid. It can be made of a fiber, a wire strand, or an independent wire rope. rope can be wound in either a right or a left helix. Wire rope terminology refers to a right regular lay or left lang lay. The terms right and left refer to the helix of the strand within the rope, while the lay refers to the relationship between the helix of the wires in the strand and the helix of the strand in the rope. A regular lay rope has the wires in the strand wound in the opposite direction to the strands in the rope, whereas a lang lay rope has the wires in the strand and the strands in the rope wound in the same direction. The rope core can be either another strand, a smaller rope called the independent wire rope core (IWRC), or a fiber. A non-rotating rope (also known as a rotationresistant rope) is a specialty rope that consists of multiple layers of strands where different types of lays are alternated to reduce the natural rotation of the rope. The wear that occurs within ropes used in mine hoisting operations usually occurs as the result of one of three types of contact: (1) contact of the outer strands of the rope with an external member, such as a sheave, drum, or layer of rope on the drum, a contact that is often called crown wear； (2) line contact between wires within a single strand or between strands； and (3) point contact between wires within a single strand or between strands. Actual wear of the wires results from the combination of stresses that develop at these contact areas during tensioning of the rope, and during localized movement as the rope is bent, loaded and unloaded. Crown wear appears as a reduced cross section on the outside wires of the rope Fig. 2(a). Wear between strands appears as nicks, which are easily visible as oblong wear scars Fig. 2(b). A characteristic pattern, consisting of one or more nicks with a similar orientation and depth, forms on each wire at the multiple-wire contact site between strands. This characteristic pattern of nicks created by point and line contacts between strands is known as trellis or interstrand nicking Fig. 2(c). One evaluation of wear in a wire rope has revealed that crown wear results from abrasion Fig. 3(a), and interstrand nicking results from fretting Fig. 3(b), with differences in appearance due to the severity of the wear mechanism 2. 3. EXPERIMENTAL PROCEDURE The two rope segments were approximately 10 ft in leng.The bad segment contained numerous breaks, and was in the vicinity of the location requiring retirement. The good segment contained no breaks, and came from the dead wrap on the drum (Fig. 4). During service, the bad segment of the rope experienced cyclic bending stresses from both the head sheave and the drum, as well as varying tensile stress from the weight of the rope and the counterweight. The good segment of the rope experienced some tensile stress from the weight of the rope and the counterweight. All wires were disassembled and labeled by rope segment, layer (outside strands = layer 1 to core = layer 5), strand, and wire position, as shown in Fig. 5. Broken wires were only found in the bad rope segment. In this segment, all breaks were contained within two outside layer strands, and one strand from the third layer. These three strands also contained the construction anomaly referred to as a dive. These were named dives because, while visually following outside wires around a strand, it was noticed that a wire would occasionally dive into the interior of the strand,and could no longer be followed visually. A different wire would come out of the interior of the strand, and take the position of the outside wire that disappeared. It was later determined that, beyond the axial location of the dive, the king wire from before the dive functioned as an outside wire, and the outside wire from before the dive functioned as a king wire. One such dive is shown in Fig. 6. Additionally, one strand from the good rope segment contained a dive, but no associated wire break. Although only the strands that contained dives contained wire breaks, not all dives had a corresponding wire break, nor were all wire breaks found at a dive. During a dive, a king wire and an outside wire physically change position within the strand. This presented a difficulty in labeling the wires and performing statistical comparisons. For labeling purposes, king wires were initially identified by strand position referenced to one end of the rope segment. However, many of the planned evaluations were based on groupings of nominally identical wires. Therefore, for analyses, both king and outside wires were determined solely by diameter. Implicit in these analyses is that the conclusions pertain to a strand that does not contain dives. The chemistry of all groups of wires in the rope segments were examined. Since the alloying composition of a wire can have a large affect on the mechanical response, (1) the alloying composition of broken and unbroken wires in the bad segment were evaluated for significant differences, and (2)the overall alloying composition of each individual layer was evaluated. The alloying composition of the good segment was assumed to be identical to that of the bad segment: therefore, chemical analyses of the wires from the good segment were not performed. However, since king wires do not have the same diameter as the outside wires, there is no reason to expect that they are from the Fig. 3. (a) Abrasive wear is commonly seen as the principal mode of damage in wires that are exp osed to external surfaces. (b) Fretting results from the relative motion between wires, such as is seen at nicks. Fracture craters due to delamination are present. Some material has been extruded from the area of contact. same steel heat. Therefore, t,he chemistry of the king wires was evaluated separately from the outside wires. The following elements were determined: carbon, sulfur, silicon, phosphorus, manganese, chromium and nickel. Carbon and sulfur were determined by gas analysis, and silicon, manganese, phosphorus and chromium by wet chemistry methods. In order to obtain a statistical representation of the alloying composition, multiple samples from each layer were analyzed. The results are reported in Table 1. Torsion tests were performed according to the American Petroleum Institute (API) Specification for Wire Rope 3. Table 2 lists the requirements for the minimum number of torsions (i.e. the number of twists to failure) to be attained by wires made out of electric furnace steel after fabrication into wire rope. In addition to the API requirements for minimum torsions, Table 2 also lists the average number of experimentally determined torsions for wires in the good segment and the bad segment, and for broken wires in the bad segment (XGOOD, XBAD, XBROKEN, respectively). A column labeled 0.3J(GOOD is included as a comparison to a practice by the Ontario Ministry of Labour. The Ontario Ministry of Labour tests ropes before they are put into service to determine initial reference values, and subsequently tests periodic cutoffs. They recommend caution when the number of Fig. 4. Schematic of hoisting operation. The rope in question came from the counterweight of a double drumhoist. The segment requiring removal was at the location marked bad section. The comparison sample(good segment) came from the dead wraps on the drum. torsions drops to 30% of the initial reference value, and recommend that ropes be retired when the number of torsions drops below 15% 4. Tensile tests were performed according to the API Specification for Wire Rope 3. Table 3 lists the requirements for the average minimum breaking strength to be attained by wires made out of electric furnace steel after fabrication into wire rope. In addition to the API requirements for minimum tensile strength, Table 3 also lists the experimentally determined average breaking strength for wires in the good segment, the bad segment, and broken wires in the bad segment ()?GOOD, XBAD, BROKEN, respectively). Metallographic and fractographic investigations were carried out in order to identify the cause(s) of failure of individual wires. For the metallographic investigation, one outside and one king wire from each strand layer of both the good and the bad segments were evaluated in the transverse direction at sites of general wear, crown wear, and nicks between adjacent strands. These samples Fig. 5. Construction ofretired hoist rope. Wires in the rope were examined as a function oflayer (outside=layer 1, core = layer 5) and strand position (wires 15 = outside wires, wire 7 = king wire). Strands in each layer were labeled in a clockwise relationship to strand 1, an arbitrarily chosen reference strand. For illustration purposes, the two strands from layer 1 that contained wire breaks (strands 2 and 13) are shown. Fig. 6. Appearance of a dive. A dive is a location where an outside wire and a king wire switch positions in the strand structure. White arrows indicate positions where an outside wire moves into the interior of the strand to assume the function of a king wire. were evaluated for decarburization, cracks, martensite, and the appearance of the wear scar. In addition, wires involved with dives were also evaluated. 4. EXPERIMENTAL RESULTS AND DISCUSSION 4.1. Rope construction The construction anomalies were named dives, and are locations where an outside wire and a king wire switch position in the strand structure. Along the strand axis, the interchange of the two wires will take place over a length of several centimeters, and results in a larger than normal strand diameter (Fig. 7). Unusual and unexpected wear and/or deformation will take place between the wires within the strand. In some cases, as also shown in Fig. 7, this is observed as deep nicks (gouges). In other cases, the result will be extensive flattening of the wire surface and/or excessive crown wear (Fig. 8), with the amount of crown wear increasing as the proximity to the dive increases. In addition to the wear and deformation, the interchange of wires, especially of different diameters, will alter the load distribution in the strand. During disassembly, 12 dives were identified in three different strands in the bad segment. All wire breaks were found in these three different strands (Figs 9-11), and were often located at or between dives. In contrast, only one dive was found in the good segment (Fig. 12), and there was no associated wire break. In wire rope design, king wires typically have a larger diameter than outside wires. Overall, the king wires (wire 7) had a diameter of approximately 2.95 mm, in comparison with Fig. 7. Dive from layer 1, strand 2. The strand diameter at the location of the dive is larger than elsewhere, as is shown by the two white arrows. The gouge produced as a result of this expanded diameter is shown by the black arrow. Fig. 8. Dive from layer 1, strand 13. A total of four wire fractures are visible, and two are matching fractures. The location where the king wire switches position and becomes an outside wire is at the location marked dive. This wire shows extensive flattening and crown wear just prior to its fracture location. The two gray arrows point out differences in the severity of the crown wear. As the location of the dive is approached, the crown wear of the surrounding wires becomes m ore severe. Fig.9. Wire diameters and location of wire breaks for layer 1, strand 2, bad rope segment. The shaded portion of the wire has a significantly larger diameter. The bottom illustration shows the relationship of dives and wire breaks in the assembled strand. (Dimensions are in mm.) 2.82 mm for the outside wires. In attempting to group like wires/sizes, it was found that a continuous king wire could not be identified in strands 2 and 13 from layer 1 as illustrated in Figs 9 and 10 . This, in addition to the difficulty unwinding strands containing dives, suggests that the anomaly was not created during service. Fig. 10. Wirc diameters and location of wire breaks for layer 1, strand 13, bad rope segment. The shaded portion of the wire has a significantly larger diameter. The bottom illustration shows the relationship of dives and wire breaks in the assembled strand. (Dimensions are in mm.) 4.2. Chemical analysis Wire ropes used in the United States are not required to meet alloying standards. However, the API does require that the wire be produced from: (1) acid or basic open-hearth, (2) basic oxygen, or (3) electric furnace steelmaking processes； and that the wire so produced meets certain mechanical property specifications, e.g. breaking strength and torsional requirements, dependent upon the steelmaking process used. Breaking strength and torsional requirements are highly dependent on alloying composition, and API-acceptable results have been developed for each of the three different steelmaking processes. Therefore, the type of steelmaking process needs to be determined for later comparisons with API specifications. The chemistries of the wires in Table 1 are typical of an electric furnace steel 5. Residual alloying elements (manganese, chromium and nickel) and impurities (sulfur and phosphorus) are generally higher in electric furnace steel than in open-hearth or basic oxygen steel. In general, higher levels of alloying elements result in lower ductility and higher strength. This is reflected in the API specifications, where the electric furnace steel has the highest requirement for tensile strength and the lowest for torsion. The steel used in this rope was considered to be produced in an electric furnace. This was later verified by the rope manufacturer. A multivariate analysis of the chemical analysis data was performed to determine if differences in chemical composition exist between the different layers of wires. The analysis revealed that there is a significant difference in the chemistries between the first three layers and the two layers that comprise the independent wire rope core. The results can be summarized as follows: (1) Layers 1 3 contain wires with very similar composition, and are probably obtained from the same heat of steel. Furthermore, the outside wires from layers I-3 were obtained from one heat of steel, and the king wires from the same layers were obtained from another heat. It should be noted that layer 2 appears to be produced from the same steel heats as layers 1 and 3, yet contains no wire breaks of either king or outside wires. (2) Layers 4 and 5 have significantly different composition from the first three layers, and are probably not obtained from the same heat as layers 1 3. (3) Layers 4 and 5 differ significantly from each other, and probably do not come from the same heat. Again, the king wires appear to be from a different heat than the outside wires. In all, it appears that there are six distinct heats of steel represented in this rope. Independent of the type of steelmaking process used, one of the primary questions to be addressed is whether the wire material itself is responsible for premature failure of the wires. As can be seen in Table 1, the chemical analyses of broken and unbroken wires in the bad rope segment are very similar. A multivariate analysis of variance shows no significant difference between the chemistries,with the possible exception of the nickel content of the layer 1 king wires. Although the statistical analysis identifies the nickel content as being significantly different, from a practical standpoint the difference is not great enough to affect the behavior of the material. It appears that the steel used for this wire rope came from six distinct heats from an electric furnace. All of the broken wires were found in layers 1 and 3, which would comprise only two of six distinct steelmaking heats identified. No significant difference was found between the broken and unbroken wires. It can, therefore, be concluded that it is highly unlikely that the overall chemistry of the wires was responsible for the wire breaks. 4.3. Torsion results For the rope segments examined, the number of torsions may reasonably be expected to be lower than those in the API specifications, due to fatigue and wear degradation during service. However,as can be seen from Table 2, the torsions generally met or exceeded the AP! specifications. It should be noted that the API specification evaluates the individual torsions, not the averages, whereas Table 2 lists the averages. When individual torsion results are evaluated, more than 90% of outside wires from layer 1 (both segments) and 50% of the outside wires from layer 4 (bad segment) meet this criteria. Since torsion results are highly dependent on surface imperfections such as crown wear and trellis patterns (wear produced as a result of contact between the outside wires in adjacent strands), lower torsion results for these two wire groups are not unusual. For the rope segments examined, the number of torsions may reasonably be expected to be lower than those in the API specifications, due to fatigue and wear degradation during service. However, as can be seen from Table 2, the torsions generally met or exceeded the AP! specifications. It should be noted that the API specification evaluates the individual torsions, not the averages, whereas Table 2 lists the averages. When individual torsion results are evaluated, more than 90% of outside wires from layer 1 (both segments) and 50% of the outside wires from layer 4 (bad segment) meet this criteria. Since torsion results are highly dependent on surface imperfections such as crown wear and trellis patterns (wear produced as a result of contact between the outside wires in adjacent strands), lower torsion results for these two wire groups are not unusual. (1) The outside wires of a strand experience crown wear and/or trellis contact, a cumulative process that affects the surface quality of the wire and lowers the overall torsions. (2) King wires do not experience crown wear or trellis contact, and no appreciable difference in the torsion values was seen. The torsion test is geared towards testing ductility. The API specifications provide for a minimum ductility to be present in a newly fabricated rope. On the other hand, the Ontario Ministry of Labour recommendations provide guidelines for removing a rope based on a decrease in ductility. The initial ductility is primarily a function of the steel chemistry and the wire drawing process. After a rope is put into service, the ductility will change as a function of fatigue and wear. As can be seen,the ductility is similar to that required for a newly fabricated rope, and far exceeds the Ontario Ministry of Labour guidelines for removal. Therefore, it appears that the ductility of the wires in both the good and the bad segments is sufficient. All the torsion results met or exceeded the API requirements for wires removed from newly fabricated wire rope, even though the wires were removed from a used rope. The number of torsions of wires removed from the good rope segment was significantly greater than for those removed from the bad rope segment, but was limited to the outside wires of a strand. These differences are most likely a result of crown wear and/or trellis patterns. There was virtually no difference in the number of torsions between broken and unbroken wires. Therefore, it is highly unlikely that the wires failed due to poor ductility. 4.4. Tensile results The breaking strengths listed in Table 3 generally do not meet the minimum requirements for wires produced from electric furnace steel. Breaking strength requirements should more accurately be called breaking load requirements because the requirements list the minimum load-carrying ability of a given diameter wire. Minimum breaking loads will depend on the cross-sectional area as well as the material property known as the ultimate tensile strength. When crown wear and trellis patterns are present, the cross-sectional area is reduced. The result is that the wire will generally break at these sites of reduced cross section. However, the API specifications are for wires removed from newly fabricated ropes, presumably with uniform cross sections. It would be reasonable to find lower strengths in wires from a rope removed from service, e.g. a rope with crown wear and trellis contact. This effect is probably responsible for the drop in strength seen in the broken outside wires from layer 1. Dives create high wires (analogous to high strands) which experience more material removal from crown wear and deeper nicks from trellis contact. The differences in breaking load between the king wires in the good and bad segments for the first three layers was found to be highly significant. An effect similar to this has been seen by the Bureau of Mines Pittsburgh Research Center when testing rope segments 6. They have noted that the rope breaking strength may initially increase, and then drop off significantly as the rope approaches the end of its useful life. For ropes, the initial increase in breaking strength is generally attributed to break-in and the flattening of contact sites between wires. Although there is a significant difference between the breaking loads for the wires in the good and bad segments, there is not a significant difference between the breaking loads for the broken and unbroken wires in the bad segment. Although interesting, the increase in strength of the wires does not appear to be related to wire failure. The tensile test is used to evaluate the minimum strength of the wires. Wires that are not of the minimum strength run the risk of being overloaded during normal use, and will also have shorter fatigue lives. Signs of overloading, such as ductile cup-cone failures, were not seen. The average strength of the wires is generally acceptable when compared with the strengths listed for other steelmaking processes. With the exception of results for the broken wires in the outside layer (which appears to be related to a loss of metallic area), there is no significant difference in the broken and unbroken wires in the bad segment. The average breaking strength of the wires removed from both the good and bad segments failed to meet the minimum API specifications for wires made out of electric furnace steel. With a few exceptions, the average breaking strengths exceeded those required for basic oxygen steel. The loss of strength of broken outside wires from layer 1 is attributed to the presence of crown wear and trellis patterns. King wires showed an unexplained increase in strength between the good segment and the bad segment, but there was no significant difference in strength between the broken and unbroken king wires. It seems unlikely that inadequate tensile strength is responsible for the wire breaks. 4.5. Metallography Decarburization was observed on wires from layers 1-3. The full depth of decarburization was approximately 15-20/tm, or a little over 1% of the diameter of the wire. Although decarburization detrimentally affects fatigue, the effect is much smaller in magnitude than that of a surface blemish such as crown wear or trellis contact. The amount measured should not have a noticeable effect on the fatigue life of the rope 7. Two types of cracks were observed in the metallographic samples. The first type of crack was radial, less than 50 pm, and generally emanated from a surface pit. The pits and cracks appear to ollow the incursion of decarburization into the wire. This is not unexpected since the ferrite resulting rom the decarburization will pit preferentially during the pickling process. Since the cracks appear n almost all of the samples from layers 1 3, regardless of location, it is highly unlikely that the adial cracks account for the differences in fracture behavior between the good and bad segments. The second type of crack propagated parallel to the surface of the wire, and was located at both rown wear and nick sites. The size and appearance of this type of crack took a variety of forms.At crown wear scars, various degrees of abrasion were found, many samples having wedge formation nd heavy plastic deformation. Some cracks were seen separating the wedge from the main body of he wire. Smaller cracks often appeared in the middle of the crown wear site, and separated the lip f material left after abrasion from the base metal itself. Unlike the abrasion found at the crown ear sites, the wear mechanism present at the nick sites tended to be sliding wear or fretting. The liding wear produced considerable deformation in the pearlitic structure, while fretting tended to emove material by spalling. In all cases, the cracks appeared roughly parallel to the surface, and ropagation of the cracks produced a metallic flake as opposed to a transverse fatigue crack. These echanisms, which are what would be expected given the nature of the interactions within the rope nd with its environment, are the same as found at crown wear and nick sites in other ropes 2. It is ighly unlikely that these mechanisms contributed to premature removal of the rope. Martensite, a suspected nucleation site for fatigue cracks, was not readily identified. Using a natal etchant, only small, thin areas were identified as martensite. It should be noted that there is some question as to whether the white-etching layer observed in wear of ferrous materials is actually martensite. A thin white layer, less than 15/tm, was observed at some nick and crown wear sites in both segments. At some locations, surface cracks that turned and followed the boundary of the white layer were visible. It is felt that the cracks associated with the white layer led to spalling, and are not responsible for the premature removal of the rope. A wide disparity of inclusions was noticed on initial examination. In relation to each other, these nclusions ranged from minimal in size and number to large in size. Since inclusions can reduce the load-carrying capability of a wire as well as decrease its fatigue performance, the number and size of inclusions was investigated. The Making, Shapin9 and Treatin 9 of Steel mentions a cleanliness rating of 0.1).3 vol % inclusions in the range of 10-50 m in diameter for continuous casting 8. Of 69 transverse samples, only 12 had inclusions that were in that range, and these were typically ! 0-25 #m. In the longitudinal direction, the cleanliness rating ranged from 0.1 vol % to approximately 0.75%. (It should be noted that all inclusions are included in this value, not just those greater than 10/m. In addition, only one field was used, leading to a large statistical error.) These observations suggest that, although large inclusions are present, they are within the range expected in this type of steel. Large inclusions and/or clusters of inclusions were found in both the good and the bad segments, as well as at general wear sites, crown wear, and trellis sites. Therefore, it does not appear that there is a correlation between inclusion content and/or size and rope segment, layer, wire, or wear type. Extensive metallographic analyses were performed on wires removed from the two rope segments.Decarburization was found on all outside wires from the first three layers, but was uniform between the segment in question and the comparison. Two types of cracks were observed in the samples.The first type was a radial crack that appeared in relation to the decarburization, and was observed the length of the wire. The second type of crack occurred at wear sites on both the good and bad segments, and on both the broken and unbroken wires, and was observed to propagate parallel to Failure analysis of a mine hoist rope 37 the wire surface. This type of crack most likely contributed to spalling and material removal at the wear site as opposed to initiating a fatigue crack in and of itself. An extensive search was undertaken to locate the appearance of martensite at wear surfaces. The search revealed small locations that could possibly be martensite, but the depth is much less than has been reported in the literature. All nomalies noticed during the metallographic analysis appeared in both segments without regard to broken or unbroken wires. Therefore, it is highly unlikely that microstructural anomalies were responsible for the wire breaks. 4.6. Fractogaphy A fractographic study of 12 fracture locations including five matching fractures was performed to identify characteristics of: (1) fracture location, and (2) crack initiation. Of the 12 fracture locations, nine were identified as occurring at crown wear sites, two as occurring at trellis sites, and one was too obliterated to determine its location. The relationship of the wire failures to dives was also sought. The movement of wires within a strand creates faint wear patterns between wires that are in contact, allowing the placement of adjacent wires to be identified. Adjacent wires within a strand follow a helical path around the king wire, and, although the wires twist, the patterns around the wires are evenly spaced, and continuous between crown wear patterns. The disruption of these wear patterns was considered as evidence of a dive (a location where two wires switch position in the strand). As such, nine of the fractures were positively identified as being in the location of a dive. Most of the wire fractures had two identifiable crack initiation sites. For the failures occurring at crown wear sites, initiation often occurred at the actual crown wear site, located either at the center or at a corner. There was usually another failure site located opposite the crown wear site at the location of the faint wear patterns. Often this wear pattern was of the wire associated with the dive. For the two failures that occurred at trellis sites, the wear associated with the dives was closely associated with one of the nicks. The amount of deformation present as well as the remaining material was evaluated. Some of the crown wear fractures had one-third to one-half of the wire cross section removed by abrasion Others experienced considerable flattening in addition to the loss of cross-sectional area. The trellis nicks associated with the wire fractures were also (qualitatively) larger than the nicks seen elsewhere on the ropes. Therefore, it is felt that the effect of the wire dives on the wire fractures was twofold. First, the dives disrupted the close-packed structure of the strand, and produced locations where certain wires were high. If the high wires were on the outside of the rope, the result was increased wear and/or compression of the wire. If the high wires were in the interior of the rope, the result was deeper than normal nicks on adjacent strands. Second, the wear characteristics and stress distribution were altered in the presence of a dive. In many cases, this contributed to either primary or secondary crack initiation. In summary, fractography was performed on wire breaks removed from the rope. Of the fractures that were not obliterated, most could be identified as being in the location of a dive by wear patterns. The process by which the wires failed varied. Clearly, some of the wires had excessive crown wear, and failed in relation to a loss of metallic area. Fractures at crown wear sites associated with dives had as much as one-third to one-half of the cross-sectional area removed. The interchange of wires at a dive produced unusual wear patterns with adjacent wires, and these wear patterns often appeared as an initiation site of the fatigue crack. Fractures at trellis sites experienced deeper nicks than were seen elsewhere in the rope. In one case, a large gouge caused by an adjacent wire (larger than that shown in Fig. 7) was identified as initiating the wire break. Although a variety of failure mechanisms were present, the common factor was the proximity of a dive. The dive either accentuated a normally occurring mechanism (crown wear) or was the cause of an unforeseen mechanism (gouging). 5. CONCLUSIONS A series of experiments was designed: (1) to compare the broken wires in the bad segment with the unbroken wires in the bad segment, and (2) to compare the wires in the bad segment with those in the comparison segment. Chemical analyses, tensile tests, torsion tests, metallography, and fracture analysis have all been performed. It was determined that, although six different steelmaking heats were identified, there was no correlation with broken and unbroken wires. A significant difference was found in the torsion between the good and the bad segments (attributed to in-service surface wear), but not between the broken and unbroken wires. The results all met or exceeded the API requirements for wires removed from a new rope, so it is highly unlikely that the wires failed due to poor ductility. The tensile results exceeded those for new wires made from basic oxygen steel. Again, a significant difference between the broken wires and the unbroken wires was not observed, so it seems unlikely that inadequate tensile strength is responsible for the wire breaks. Inclusions, decarburization, cracks and martensite ere all evaluated. All anomalies noticed during the metallographic analysis appeared in both segments without regard to broken or unbroken wires. It is highly doubtful that the metallurgical structure was responsible for the wire breaks. Differences in the chemical analyses, tensile tests, torsion tests, and metallography do not correlate with the presence or absence of broken wires. The construction anomaly called a dive was found to be related to the presence of broken wires. The three strands in the bad segment that had wire breaks were also the three strands that contained dives. One strand in the good segment contained a single dive, but no wire break. Dives produce a larger than normal strand diameter in the local vicinity, which results in unusual and unexpected wear and/or deformation. Fractography of the wire breaks showed the breaks to be associated with gouges, flattening, or severe crown wear, all of which can be attributed to the disruption of the strand structure produced by a dive. It appears that the wear and/or deformation caused by the presence of the dive accounts for the wire breaks. The number and distribution of wire breaks were, in turn, responsible for the rope being retired prematurely. REFERENCES 1. U.S. Code of Federal Regulations. Title 30 Mineral Resources； Chapter l-Mine Safety and Health Administration, epartment of Labor； Subchapter N-Metal and Nonmetallic Mine Safety； Part 56, Subpart R, and Part 57, Subpart R: ubchapter OCoal Mine Safety and Health； Part 75, Subpart O, and Part 77, Subpart O； 1 July 1989. 2. Sehrems, K. K., Do,an, C. P. and Hawk, J. A., Journal o Materials Engineerin 9 and PerJormance, 1995, 4, 136. 3. American Petroleum Institute, Spec!fication/br Wire Rope. APISpec(fication 9A (Spec 9A), 23rd edn. Washington, DC,1984. 4. Djivre, M., Mine ShaJ Ropes: Ontario Destructite Wire Testin,q Program. Ontario Ministry of Labour, Sudbury, Ontario,16 January 1991, p. 5. 5. Dove, A. B., Ferrous Wire. Vol. I: The Manu/tcture fFerrous Wire. The Wire Association International, Guilford, CT,1989. 6. Miscoe, A. J., Private communication, 1990. 7. Mayer, M., Private communication, 1995. 8. Lankford, W. T., Jr., Samways, N. L. Craven, R. F. and McGannon, H. E., eds, The Making, Shaping, and Treating o teel, 10th edn. Association of Iron and Steel Engineers, Pittsburgh, PA, 1985. 中文翻譯： 礦井提升機(jī)繩索的失效分析 摘要 對提前報(bào)廢的提升鋼絲繩進(jìn)行廣泛的調(diào)查。這些繩索比預(yù)想的要早報(bào)廢，但是因?yàn)樗鼭M足金屬絲中斷的號(hào)碼和分配。它的化學(xué)性質(zhì)，強(qiáng)度極限和延展性都較好的滿足新繩索的標(biāo)準(zhǔn)。金屬組織顯示局 部的不規(guī)則，但是這些現(xiàn)象在好的和壞的段兩者都有出現(xiàn)，在斷了和未破損的電線都存在。僅僅有一項(xiàng)仿佛和電線的故障和出現(xiàn)不規(guī)則結(jié)構(gòu)有關(guān)系。這些不規(guī)則結(jié)構(gòu)，術(shù)語叫 潛水 ，使繩股的結(jié)構(gòu)分裂，還可能導(dǎo)致過度的壓力磨損和罕見的磨耗圖紋。繩索中斷的地方全部發(fā)現(xiàn)在 潛水 附近。這個(gè)調(diào)查提出這個(gè) 潛水 是卷揚(yáng)繩過早的報(bào)廢的原因。 1、簡介 鋼絲繩傳遞著巨大的軸向負(fù)荷和展示極度的揉曲性。另外 ,鋼絲繩設(shè)計(jì)使它當(dāng)一些電線中斷而沒有完全損失時(shí)經(jīng)受得起。這些特征使得鋼絲繩在許多體系中成為一個(gè)萬能的元件。鋼絲繩被用于許多工業(yè)，包 括采 礦，濱外海上石油生產(chǎn)和牽引或荒野的船。奧爾巴尼研究中心已經(jīng)研究鋼絲繩的降解機(jī)理，目的是為了更精確地推算繩索的使用年限。在和Henderson Mine 合作下，奧爾巴尼研究中心人員研究使用壽命出乎意料短暫的報(bào)廢后的提升機(jī)繩索。在工作 9 個(gè)月以后，這繩索因?yàn)樗^容許的每敷管長度斷絲的脈碼調(diào)制數(shù)而報(bào)廢。選中繩索的兩部分倆來研究。一部分是在或靠近因?yàn)閿嘟z而要求報(bào)廢的一段（此后被認(rèn)為是這錯(cuò)誤程序段），另一部分是來自包著金屬的（此后被認(rèn)為是好的部分）。分析這兩部分在結(jié)構(gòu)，鋼的成分加工方法，和機(jī)械性能上的差異。因?yàn)槿?們感到繩索是過早地報(bào)廢，分析的目的是識(shí)別，和如果可能的話定量的說明繩索中斷的任何差異。 首先的研究集中在兩個(gè)明白的問題：（ 1）繩索的好的和壞的部分有什么差異，（ 2）在中斷和在壞段里未破損繩索是否存在任何實(shí)際的或機(jī)械的的差異？ 2、背景 鋼絲繩由金屬絲繞成一束組成叫做 繩股 ，然后繞成繩索（圖 1）。在繩股的在最中心的金屬絲為繩子的主要部分，為為纏繞它的金屬絲提供支撐。一或多層可能是包在主要金屬絲來構(gòu)成繩股。最后層構(gòu)成繩股的最外面，從而這金屬絲叫做室外線。在一個(gè)繩股里數(shù)量，大小和鋼絲排列方式以及繩股的數(shù)目 決定它的結(jié)構(gòu)。繩股里的金屬絲和繩索里的繩股是各自向左或者向右螺旋纏繞形成的。鋼絲繩術(shù)語引用了右向逆捻或左向逆捻的術(shù)語。右旋和左旋要看繩索里繩股的螺旋方向，這個(gè)結(jié)論引用繩股里金屬絲的螺旋方向和繩索里繩股的螺旋方向的關(guān)系。在逆捻鋼 絲繩的上，繩股里的金屬絲纏繞方向和繩索里的繩股是相反的，然而同向捻鋼絲繩纏繞方向是一樣的。鋼絲繩繩心可能是繩股，較小繩索 叫做繩式股芯（獨(dú)立鋼絲繩芯） 或者纖維。不旋轉(zhuǎn)鋼絲繩（亦稱抵制旋轉(zhuǎn)繩索）是一個(gè)特殊的繩索，由倍數(shù)的鋼絞線層組成，鋼絞線層減少了正常繩索的旋轉(zhuǎn)。 圖 1。金屬絲繩索的三個(gè)基本組成成分是金屬絲，繩股和核心。金屬絲是單個(gè)、連續(xù)的金屬棒。繩股是對稱排列、成螺旋形纏繞組合的金屬絲。核心是金屬絲繩索的中心構(gòu)件。繩索又一個(gè)纖維，金屬絲繩股或繩式股芯組成。這三部分組合成金屬絲繩索。 繩索通常被用于 礦井提升機(jī)的工作里因?yàn)樗腥N聯(lián)系。（ 1）接觸繩索的繩股外面的有一個(gè)套件，例如一個(gè)滑車輪，金屬桶，或金屬桶上的繩索層，簡而言之經(jīng)常叫做頂部磨損；（ 2）在單個(gè)繩股或繩股之間里面金屬絲之間有線接觸；（ 3）在單個(gè)繩股或繩股之間里面金屬絲之間有點(diǎn)接觸。金屬絲的實(shí)際磨損是由應(yīng)力在繩索拉緊和因?yàn)槔K索彎曲、裝卸的局部運(yùn)動(dòng)中接觸面積發(fā)展而來的組合引起的。頂部磨損表現(xiàn)為繩索在外面的金屬絲橫截面減少如圖 2（）。繩股之間的磨損表現(xiàn)為刻痕，因?yàn)槭情L方形磨損傷痕而顯得很明顯如圖 2（）。一個(gè)特殊的圖案，由一或多類似的方向和 深度的刻痕組成，各個(gè)金屬絲繩股之間的接觸部位緊接著排著。這些刻痕的特征圖由繩股之間點(diǎn)和線接觸構(gòu)成的，被稱為 格子結(jié)構(gòu) 或異?？毯?如圖 2（）。由磨擦引起的頂部損耗顯示鋼絲繩的磨損 如圖 3（ a） , 由磨損引起的刻痕 如圖 3（ b） , 由于嚴(yán)重的磨損機(jī)構(gòu)存在外表上的差異。 3、實(shí)驗(yàn)步驟 兩部分繩索大約 10 英尺長度。壞的部分包含許多的斷裂和要求報(bào)廢段的附近。好的部分不包含斷裂，并且來自報(bào)廢的金屬繩索 (見圖 4)。在工作期間 ,繩索的壞的一段受到來自滑輪和金屬桶的環(huán)狀的彎曲應(yīng)力，以及來自繩索的和平衡物的重量的變化 張應(yīng)力。好的一段繩索受到來自繩索的和平衡物的重量的變化張應(yīng)力。 金屬絲分為繩索部分，層（外面繩股 = 1 層核心 = 5 層），繩股和金屬絲，如圖 5 所示。斷絲僅僅發(fā)現(xiàn)在壞的繩索部分。在這部分里，全部的斷裂包含在外 面兩層繩股里面和繩股的第三層。這三繩股也包含被認(rèn)為是 潛水 的不規(guī)則結(jié)構(gòu)。這些被稱為 “ 潛水 ” 是因?yàn)楫?dāng)一個(gè)繩股的可見的生效的 室外線，人們注意到繩索便會(huì)隔些時(shí)候 潛水變成繩股的內(nèi)部，就再也不生效了。一不同的金屬絲便會(huì)從繩股的內(nèi)部出來，取代消失的室外線的位置。進(jìn)一步斷定，潛水超過軸的位置，繩索的主鋼絲阻攔 潛水起室外線作用，室外線阻攔潛水起繩索的主鋼絲作用。一個(gè)這樣的潛水如圖 6所示。另外，繩股阻攔好的繩索部分容納潛水，但是和金屬絲斷裂沒有關(guān)聯(lián)。雖然繩股包含潛水包含金屬絲斷裂，但金屬絲斷裂和俯沖也不一致，也不是全部金屬絲斷裂都發(fā)現(xiàn)在潛水的地方。 在潛水期間，主鋼絲和室外線在多股電纜芯線里面位置完全地轉(zhuǎn)換。這個(gè)帶來在線的標(biāo)簽故統(tǒng)計(jì)比較的困難。為了標(biāo)明用途，主鋼絲通過繩股到繩索另一端 位置基準(zhǔn)認(rèn)出。然而許多平面圖根據(jù)同一的金屬絲名稱上的組計(jì)值。為了分析，主鋼絲和室外線單獨(dú)地由直徑?jīng)Q定。就是這些分析的結(jié)論屬于未容納潛 水的繩股。 圖 2。（）在頂部磨損位置的疲勞裂縫。頂部磨損是在和滑車輪，金屬桶或其他的外部的元件接 觸的繩索的室外線出現(xiàn)。（）在凹痕處的疲勞裂縫。金屬絲之間的接觸引起凹痕，突出的凹痕是在鄰近的多股金屬絲成為一繩股的地方發(fā)現(xiàn)的。（）鄰近的繩股通常有許多金屬絲接觸，產(chǎn)生一個(gè)可識(shí)別的凹痕叫做格狀圖案。凹痕由箭頭記號(hào)指出。三條凹痕構(gòu)成一個(gè)格狀圖案。 圖 3。（ a）磨損量一般看作是損害暴露于外部的表面金屬絲的主要形式。（ b）摩擦腐蝕是由金屬絲之間相對運(yùn)動(dòng)引起的，例如在凹痕處。分層的出 現(xiàn)導(dǎo)致斷面凹坑。一些材料已經(jīng)從接觸面積被擠出。 圖 4。提升機(jī)運(yùn)行圖解。繩索來自雙絞筒提升機(jī)的平衡物。這段要求在裝配標(biāo)記 壞的 段取出。比較樣品（ 好的 段）來自金屬桶的繞線。 圖 5。提升鋼絲繩結(jié)構(gòu)。繩索的金屬絲是一層層的（外面 =1 層，核心 = 5 層）以及繩股位置（ 1 5 =室外線，金屬絲 7 =主鋼絲）。繩股在各個(gè)層按順時(shí)針方向關(guān)系標(biāo)簽，選擇參考繩股。插圖目的是顯示兩個(gè)繩股的金屬絲斷裂（繩股 2和 13）。 圖 6.潛水的外形 .潛水出現(xiàn)在繩股結(jié)構(gòu)的室外線和主鋼絲聯(lián)接位置。白色箭頭記號(hào)指出位置在室外線移動(dòng)進(jìn)繩股的內(nèi)部去承擔(dān)主鋼絲的功能。 表格 1。壞的繩索段的鋼成分：在給定層的從所有的繩股里隨機(jī)選擇金屬絲的結(jié)果平均數(shù)。分別地測定室外線和主鋼絲，用重量百分率表示。 表格 2。報(bào)廢繩索中金屬絲的轉(zhuǎn)矩結(jié)果： APT 對新制造繩索的金屬絲要求。安大略勞工部推薦的用過繩索的 金屬絲的要求。 表格 3。報(bào)廢繩索的金屬絲的平均斷裂強(qiáng)度：列舉了由電爐鋼制造成鋼絲繩的金屬絲的 API 要求的最小值斷裂強(qiáng)度的平均數(shù)。 研究所有繩索部分的金屬絲的化學(xué)性質(zhì)。合金成分的金屬絲在力學(xué)性能上有巨大的影響，（ 1）合金成分的斷裂和未破損的金屬絲在壞的部分有重大差別。（ 2）評(píng)價(jià)全部的合金成分的各個(gè)單層。假定好的部分和壞的部分的合金成分一致的：所以，金屬絲好的部分的化學(xué)分析沒有進(jìn)行。然而，因?yàn)橹麂摻z沒有室外線一樣的直徑，就沒有理由認(rèn)為他們來自于一樣的鋼熔煉。所以，主金屬絲的化 學(xué)性質(zhì)分別地金屬絲外面來評(píng)價(jià)。下列成分可以確定：碳，硫，硅，磷，錳，鉻和鎳。碳和硫可以由氣體分析來確定，硅，錳 ，磷和鉻由濕法化學(xué)方法來確定。為了獲得合金成分的統(tǒng)計(jì)學(xué)結(jié)果，從各個(gè)層多重抽樣分析。結(jié)果見表 1。 扭轉(zhuǎn)試驗(yàn)是按照美國石油組織（ API）對金屬絲繩索的規(guī)格進(jìn)行的。表格 2 列舉從電爐鋼中制造來制造成鋼絲繩的金屬絲的扭轉(zhuǎn)的最小值（即扭轉(zhuǎn)到破壞得值）。除 API 扭轉(zhuǎn)最小值之外，表格 2 還列舉用實(shí)驗(yàn)方法確定的好的部分和壞的部分的繩索的扭轉(zhuǎn)的平均值，以及壞的部分的斷絲（ ,G O O D B A D B R O K E NX X X）。包括 0.3 GOODX 作為和安大略勞工部實(shí)驗(yàn)的比較。安大略勞工部在 他們交付使用以前測試?yán)K索測定最初的參考值作為后來試驗(yàn)周期的捷徑。他們建議當(dāng)扭轉(zhuǎn)數(shù)目跌至最初的參考值的30%的時(shí)候要警示，以及建議繩索當(dāng)扭轉(zhuǎn)數(shù)目降低到 15%的程度就報(bào)廢。 拉力的測試是按照鋼絲繩的 API 規(guī)范進(jìn)行的。表 3 列出了從中電爐鋼制造變成鋼絲繩的金屬絲的斷裂強(qiáng)度平均最小的值。除 API 要求拉力的強(qiáng)度的最小值之外，表格 3 還列舉了用實(shí)驗(yàn)方法測定的平均斷裂強(qiáng)度。包括了好的部分，壞的部分和壞的部分的斷絲（ ,G O O D B A D B R O K E NX X X）。 進(jìn)行金相的和斷口金相研究為了確定單一金屬絲破壞原因 。因?yàn)檫@金相的研究，各個(gè)繩股層的外線和主鋼絲包括好的和壞的部分在一般的 磨損，頂部磨損和在鄰近的繩股之間的刻痕位置的橫向的方向有了測定。這個(gè)樣品進(jìn)行了脫碳，裂縫，馬氏體，和傷痕磨損測定。另外還測定了金屬絲與潛水的聯(lián)系。 4、試驗(yàn)結(jié)果和討論 4.1、繩索結(jié)構(gòu) 這個(gè)不規(guī)則結(jié)構(gòu)稱為潛水，在繩股結(jié)構(gòu)室外線和主鋼絲轉(zhuǎn)換位置。平行繩股軸，兩個(gè)金屬絲便會(huì)發(fā)生一段幾個(gè)厘米的互換，于是導(dǎo)致比正常的繩股大的直徑（如圖 7）。有時(shí)罕見的和意外的磨損及畸變便會(huì)發(fā)生在多股電纜芯線金屬絲之間，也見圖 7，深的刻痕很容易觀察。在其它情況下 ，當(dāng)頂部磨損的數(shù)值增加道接近潛水時(shí)，這個(gè)結(jié)果將成為金屬絲表面和頂部過度的磨損廣泛的變平（圖 8）。除磨損和畸變之外，金屬絲的互換尤其是不同的直徑便會(huì)改變繩股的負(fù)荷分配。 在分解期間， 12 潛水是在壞的部分的三不同的繩股中確定。全部的金屬絲的斷裂是在這三股不同的繩股里發(fā)現(xiàn)的（數(shù)字 9 10），或經(jīng)常位于或在潛水之間。比較起來，僅僅一個(gè)潛水是在好的部分發(fā)現(xiàn)的，這個(gè)跟金屬絲斷裂沒有關(guān)聯(lián)。在金屬絲繩索設(shè)計(jì)時(shí)，主鋼絲的直徑一般地比室外線大?？偟恼f來，主金屬絲（金屬絲 7）的直徑大約有 2.95 毫米， 相比來說室外線有 2.82 毫米。在金屬絲的研究，據(jù)發(fā)現(xiàn)連續(xù)的主鋼絲不能確定 2和 13層如同數(shù)字 9 和 10 的圖解。這個(gè)，除困難展開繩股容納潛水之外，認(rèn)為在工作期間不規(guī)則沒有產(chǎn)生。 圖 7。 1 層繩，股 2 的跳水。潛水位置的繩股直徑比其它地方大，像兩個(gè)白色箭頭記號(hào)顯示的一樣。圓鑿是直徑展開的產(chǎn)生的結(jié)果如黑色箭頭記號(hào)顯示。 圖 8。 1層繩股 13的跳水?？偣菜臈l金屬絲的斷面是明顯的，兩個(gè)是對比斷面。主金屬絲的聯(lián)接位置變成室外線，定位標(biāo)記 潛水 。這些金屬絲顯示出大量的平化和頂部磨損，僅僅在金屬絲斷面位置前。兩個(gè)灰色箭頭指出主金屬絲磨損的嚴(yán)重差異。在接近潛水的位置，主金屬絲的變成更嚴(yán)重。 圖 9。壞的繩索部分 1 層繩股 2 的金屬絲直徑和金屬絲斷裂位置。金屬絲的陰暗部分的直徑明顯大些。底部插圖顯示多股聚集的潛水和金屬絲斷裂的關(guān)系。（尺寸為毫米） 4.2 、化學(xué)分析 用于美國的鋼絲繩沒有要求滿足合金標(biāo)準(zhǔn)。然而， API 要求金屬絲由以下幾種方法產(chǎn)生：（ 1）酸的或基本的平爐，（ 2）基本的氧，或（ 3）電爐煉鋼；金屬絲生產(chǎn)必需滿足機(jī)械性能的規(guī)格，例如斷裂強(qiáng)度和扭轉(zhuǎn)的要求，都要取決于煉鋼法的使用。斷裂強(qiáng)度和扭轉(zhuǎn)的要求很大成分是取決于合金成分， API 合格的結(jié)果已經(jīng)發(fā)展成三種不同的煉鋼方法。所以，這種煉鋼法需要比 API 技術(shù)規(guī)范更新。 在表格 1 中是代表電爐鋼金屬絲的化學(xué)性質(zhì)。其余合金元素（錳，鉻和鎳）和混合物（硫和磷）在電爐鋼比敞爐或堿性氧吹鋼的較高。一般而言，較多的合金元素會(huì)導(dǎo)致延展性降下和強(qiáng)度極限升高。這個(gè)反映在 API 技術(shù)規(guī)范上，電爐鋼 圖 10。壞的繩索部分 1 層繩股 13 的金屬絲直徑和金屬絲斷裂位置。金屬絲的陰暗部分的直徑明顯大些。底部插圖顯示多股聚集的潛水和金屬絲斷裂的關(guān)系。（尺寸為毫米） 對拉力強(qiáng)度極限有很高的要求和扭轉(zhuǎn)最小的要求。繩索用的鋼是在電爐生產(chǎn)的，這是后來被繩索廠商核實(shí)了。多變量的化學(xué)分析來測定在在不同的層金屬絲之間是否存在化學(xué)成分的差異。分析顯示在第一個(gè)三層和包含繩式股芯兩個(gè)層之間存在化學(xué)性質(zhì)放入顯 著差異。結(jié)果總結(jié)如下： （ 1） 1、 3 層的金屬絲有很類似的成分，很可能是從一樣的鋼的爐次獲得。而且 1、 3層室外線是由同一種熱處理爐次獲得的，而主金屬絲是另一種熱處理得的。人們注意到 2 層仿佛同 1 、 3 層經(jīng)過是一樣的熱處理的，然而不管是主金屬絲還是室外線都不包含段的金屬絲。 （ 2） 4和 5 層在成分上和起初三層有較大地不同，很可能是從不同的熱處理獲得的。 （ 3） 4層和 5層彼此存在很大的差別，而且可能不是來自一樣的熱處理。此外主金屬絲出現(xiàn)和室外線不同的熱處理。 總計(jì)，在繩索中一共有六不同的熱處理爐方法。 圖 11。 3層繩股 3的壞的繩索段的潛水和斷裂 的位置 圖 12。比較段 1 層繩股 7 的跳水的位置。這些是發(fā)現(xiàn)在比較段的潛水。這些和金屬絲斷裂沒有關(guān)聯(lián)。 與這種煉鋼過程 無關(guān)，一個(gè)主要的問題是鋼絲材料它本身是否跟金屬絲過早失效有關(guān)系?？梢钥幢砀?1，在壞的繩索部分的斷裂處和未破損處金屬絲的化學(xué)分析結(jié)果很類似的。多元方差分析顯示在化學(xué)性質(zhì)之間沒有顯著差異，可