SWRH72A盘条拉拔断裂分析

用光学金相显微镜和扫描电子显微镜对SWRH72A盘条拉拔断裂试样进行一系列检验分析。结果表明:SWRH72A盘条组织中出现大量粗片状的珠光体是导致盘条拉拔断裂的直接原因。大量粗片状珠光体的形成与吐丝前后的冷却速度过慢等因素有关。严格控制吐丝前后的冷却速度,防止盘条堆积过密,可获得拉拔性能优越的索氏体组织。     

切割钢丝盘条的显微组织研究

为适应切割钢丝对盘条深加工性能的高要求,研究了大拉拔塑性变形条件下盘条显微组织中渗碳体片层间距对成品钢丝性能的影响,发现显微组织的渗碳体片层间距80 nm时会降低钢丝的拉拔加工硬化率,同时也会降低拉拔后钢丝的扭转性能。在工业化生产条件下,盘条显微组织控制在索氏体和珠光体范围内,比将显微组织控制在索氏体和屈氏体范围内更适合大压缩率的拉拔,即不能盲目追求高索氏体化率。盘条的屈强比参数可作为盘条显微组织索氏体化率的参考。     

ER50-G焊丝用盘条粗拉拔断裂原因分析

通过对ER50-G焊丝用盘条及拉拔断裂样品进行化学成分和抗拉强度测试,以及金相组织、非金属夹杂物能谱检验分析,找到了焊丝断裂的主要原因.分析结果表明:ER50-G盘条内出现大量硬质不易变形的贝氏体组织及大块夹杂物,影响了焊丝拉拔过程中的铁素体及珠光体组织的变形,导致拉拔后的焊丝出现强烈的加工硬化现象,并在焊丝内的硬质脆性相部位出现断裂.     

ML40Cr冷镦螺栓法兰外圈表面开裂原因分析

ML40Cr钢Φ10mm盘条生产10.9级螺栓,经冷镦六角螺栓的法兰外圈表面出现大量密集性、斜向、“X”字型交叉裂纹现象。经对开裂螺栓解剖分析,主要与盘条退火拉拔后表层存在片状珠光体组织有关,该类组织因塑性较低、冷变形能力差等因素,在冷镦六角螺栓时,其法兰面因变形量较大容易出现开裂现象,而拉拔材表层片状珠光体与原始盘条经球化退火加热时温度过快、过高产生的冲温现象有关。     

湘钢SWRH82B/SAE1080质量分析与工艺控制

预应力钢丝、钢绞线用优质高碳盘条SWRH82B/SAE1080在拉拔过程中常出现脆性断裂现象.通过对中心缩孔和碳偏析、表面横裂纹、粗大珠光体或网状碳化物不良组织等引起断丝原因的分析,提出通过合理控制浇注温度、拉速、二冷强度、控轧控冷强度及拉拔工艺参数等措施,改进盘条实物质量,降低断丝率.     

形变温度和冷却方式对中碳钢显微组织及拉拔性能的影响

采用Gleeble热模拟试验机研究了形变温度及冷却速度对ML35钢显微组织与硬度的影响;对比分析了10B21钢SM控冷盘条和板链式控冷盘条的显微组织差异,用Minitab软件统计分析了显微组织对盘条拉拔性能的影响。结果表明:当ML35钢形变温度为750℃时晶粒明显细化,部分珠光体发生退化,渗碳体呈短棒状或颗粒状,但硬度相对偏高;降低形变后的冷却速度可粗化晶粒,降低硬度;粗大的铁素体+珠光体组织比细小的铁素体+珠光体组织具有较高的初始加工硬化率;并且在初始变形过程中,具有相对粗大的铁素体+珠光体组织盘条的断后伸长率下降偏快。     

45#硬线拉拔断裂分析

针对45#硬线由Φ6.5 mm拉拔到Φ4.6 mm时发生断裂的问题,分析了其拉拔断口及表面裂纹形貌,用金相显微镜、扫描电镜对其金相组织、夹杂物及化学成分进行分析,结果表明:45#硬线钢中存在大颗粒脆性夹杂物,降低了盘条表面的强度和塑性,使其在拉拔过程中出现横裂纹,继而引起拉拔断裂,盘条表层组织不均匀也增加了盘条断裂机率。提出了夹杂物控制和金相组织改进措施,改进后盘条拉拔到Φ3.8 mm时的断丝率不足1.5%。     

ER70S-G含钛焊接用钢盘条双相区轧制问题分析

对含Ti焊接用钢ER70S-G盘条进行双相区轧制并采用较高的吐丝温度(≥780℃),后续通过斯太尔摩风冷线缓冷,盘条出现心部晶粒细化,但边部出现环状晶粒粗大现象。试验结果表明,对盘条金相组织为铁素体或铁素体+少量珠光体组织的低碳含Ti焊接用钢盘条进行双相区轧制,盘条边部晶粒易出现环状粗大情况,影响盘条的拉拔使用性能。     

吐丝温度对ER50-6盘条性能的影响

结合天钢现有装备特点,设计出三种不同吐丝温度下的控冷工艺,研究焊接用钢ER50-6盘条的力学性能及微观组织演变规律,以提高盘条的微观组织均匀性和力学性能。研究结果表明,ER50-6盘条吐丝温度为850℃,冷却速度控制在1℃/s以内时,ER50-6盘条具有均匀的铁素体和珠光体组织,可以避免产生贝氏体组织,力学性能适中,有利于后续的拉拔加工。     

SWRH82B盘条笔尖状断口原因分析

针对SWRH82B盘条在拉拔过程中出现的拉拔断裂,通过断口形貌分析、成分分析和金相组织分析等方法对SWRH82B盘条笔尖状断口的形成原因进行分析。结果表明,由于该盘条心部存在碳偏析,形成网状碳化物等硬脆相,在拉拔过程中硬脆相易与基体形成微裂纹,随着加工的深入,萌生裂纹扩展并最终断裂。     

Microstructures and Mechanical Properties of as-Drawn and Laboratory Annealed Pearlitic Steel Wires

Near eutectoid fully pearlitic wire rod (5.5 mm diameter) was taken through six stages of wire drawing (drawing strains of 0 to 2.47). The as-drawn (AD) wires were further laboratory annealed (LA) to re-austenitize and reform the pearlite. AD and LA grades, for respective wire diameters, had similar pearlite microstructure: interlamellar spacing (λ) and pearlite alignment with the wire axis. However, LA grade had lower hardness (for both phases) and slightly lower fiber texture and residual stresses in ferrite. Surprisingly, essentially identical tensile yield strengths in AD and LA wires, measured at equivalent spacing, were found. The work hardened AD had, as expected, higher torsional yield strengths and lower tensile and torsional ductilities than LA. In both wires, stronger pearlite alignment gave significantly increased torsional ductility.     

剧烈塑性变形对珠光体钢丝奥氏体转变的影响

 用金相显微镜、扫描电镜、透射电镜、X射线衍射仪、同步热分析仪研究了冷拉拔形变对珠光体钢丝奥氏体化热处理过程和组织的影响。经过冷拉拔剧烈塑性变形后,珠光体组织呈纤维状,其片层沿拉拔轴向排列,厚度剧烈减薄,铁素体<110>丝织构强度达到饱和。经剧烈塑性变形的珠光体在奥氏体化转变时,奥氏体形核更早、更密集,且沿轴向生长;在完成等温转变后,其原奥氏体晶粒、珠光体团尺寸均明显细化,其铁素体<110>丝织构一定程度遗传到了相变后的组织中,但沿拉拔轴向排列的片层形貌特点并未得到遗传。     

The micro structure of high carbon low alloy steel for easy drawing

For better processing performance of high carbon low alloy steel wire rod,an investigation about the influence of cementite lamellar spacing on wire ’easy drawing’ performance is completed.It is pointed out that too thin cementite lamellar spacing(<80 um) reduces the strain hardening level of wire drawing, and reduce the torsion performance of drawn wire at same time.For the wire or wire rod from industrial production,compared with the micro-structure with troostite,the micro-structure with sorbite or sorbite mixed with pearlite is more suitable to the drawing process with high reduction ratio.     

Macro- and Micromechanics of Pearlitic-Steel Deformation in Multistage Wire Production

Ninefold drawing of pearlitic steel wire is investigated. On the basis of multiscale computer models, the behavior of pearlite colonies at the surface of the wire and in its central layer is analyzed. The key factors are the orientation of the cementite lamellae relative to the drawing axis, the interlamellae distance, and the shape of the cementite inclusions. On the basis of finite-element models, the laws governing the reorientation of the pearlite colonies, change in shape and size of the cementite lamellae, and localization of the deformation in the ferrite are determined. The model results are verified by means of metallographic results and industrial experiments.     

ER50-6盘条拉拔开裂原因分析

低合金焊接用钢盘条在拉拔过程中有时出现劈裂现象,为找出其原因,对每一道次的钢丝取样进行金相分析,发现劈裂钢丝对应的盘条和半成品钢丝中都存在严重的横向珠光体带状偏析,且盘条的横向带状偏析与连铸坯的内部裂纹有很好的对应关系,盘条中存在的严重横向带状偏析是造成钢丝劈裂的主要原因。     

Study of the Microstructure and Properties of ER70S-6 Wire Rods

After rolling even after drawing,a fraction of martensite may occur in the microstructure of ER70S-6 wire deteriorating the ductility and drawing performance.The mid-products of drawing for test were heat treated at 350℃ and 500℃,deformed ferrite plus pearlite plus some unchanged martensite and deformed ferrite plus pearlite plus troostite were obtained respectively.Repeat bending test was carried out on both as-drawn and heat-treated samples.The results showed that the brittleness of the as-drawn rods is not due to defects but due to the presence of martensite in microstructure.The sample heat-treated at 500℃ and cooled in oven has the best ductility.     

大应变变形珠光体钢丝微观组织结构的研究

  采用扫描电镜（SEM）观察了以不同应变量拉拔变形后SWRH72A钢丝的显微组织变化,并测量了钢丝力学性能、磁学性能随应变量增大的变化趋势。试验结果表明,随着拉拔变形应变量的增大,珠光体片层间距逐渐减小,钢丝强度随之升高。由于变形应变量的增大,微缺陷密度升高,钢丝矫顽力Hc和剩余磁化强度Mr都随之变大。而应变量较小时,钢丝比饱和磁化强度基本不变,为227.87 emu/g。当应变量增大到2.60时,样品的比饱和磁化强度升高到233.55 emu/g,计算得知钢丝中渗碳体的质量分数由未变形状态的10.8%降至8.6%。     

合金元素钒对高碳钢丝组织与性能的影响

 钒对高碳钢丝的微观组织、力学性能及热稳定性具有显著的影响。钒元素在高碳钢中主要存在于渗碳体中,可以起到强化渗碳体的作用。添加钒元素有利于珠光体片层间距的细化,还可以增加渗碳体的热稳定性,从而抑制钢丝拉拔过程中渗碳体的分解。但在拉拔应变量较大时,富含钒的渗碳体片碎化严重,会加重钢丝在镀锌过程中的球化现象,而导致钒合金化钢丝与未添加钒元素的钢丝相比,无论镀锌与否,其扭转性能均明显下降。     

φ5.35mm-2100MPa桥梁用锌铝钢丝的工艺与组织性能

 为了制备更高强度级别的桥梁缆索用热镀锌铝钢丝，通过对高碳钢盘条的成分设计、低损伤拉拔技术以及热浸镀锌铝等工艺过程的优化，成功试制出?5.35 mm-2 100 MPa级桥梁缆索用热镀锌铝钢丝。设计的SWRS92Si盘条主要成分为（质量分数）：C 0.90%～0.95%，Si 0.8%～1.1%，Cr 0.20%～0.30%。试制结果表明，?13 mm-SWRS92Si盘条经铅浴处理后，珠光体层片平均尺寸从120下降至90 nm，盘条强度上升约260 MPa。经冷拉拔与热镀锌铝后，层片宽度约40 nm的珠光体层片未明显球化，可制备出2 100 MPa级直径5.35 mm的桥梁缆索用热镀锌铝钢丝。钢丝的平均抗拉强度为2 128 MPa，平均断后伸长率为5.4%，扭转圈数平均值为22圈，断口均为平断口，镀层较均匀致密；其他性能指标均优于交通部标准JT/T 1104—2016《桥梁用热镀锌铝合金钢丝》中的要求。     

Effect of cementite morphology on pearlitic wire drawing deformation

A comparative study was conducted on the effects of lamellar cementites and globular cementites on the cold drawing process and the mechanical properties of pearlitic wire steel, with the help of metallographic microscope, scanning electron microscope, transmission electron microscope, tensile tester and hardness tester. The lamellar cementites showed the deformation capacity to some extent during the cold drawing process. As the drawing strain increased, the pearlitic wire with globular cementites evolved into the fibrous form gradually and no obvious defects were found in the microstructure. The globular cementites turned to the drawing direction without any deformation of itself during the deformation process. And micro- cracks occurred in the cementite/ferrite interface due to stress concentration caused by pinning dislocations in spherical cementites. The strength and hardness of both pearlitic wires gradually increased as the drawing strain rose. And the pearlitic wire with lamellar cementites had a higher drawing hardening rate. The ferrite <110> texture formed in both pearlitic wires during the cold drawing process. Compared with the globular pearlite, the pearlitic wire with lamellar cementites had higher ferrite <110> texture intensity. And the difference of their ferrite <110> texture intensity became bigger and bigger as the drawing strain increased.