胎圈钢丝中间热处理的工艺参数优化

为减少胎圈钢丝拉拔生产过程中的断丝现象,提高加工性能和最终产品质量,研究了加热温度、铅浴温度和淬火速度等工艺参数对胎圈钢丝性能的影响。结果表明,当φ3.5 mm钢丝的热处理线速度为18 m/min、钢丝出线温度为940 ℃左右时,可得到均匀一致的奥氏体组织,并能在铅槽处理中进一步分解获得要求的索氏体组织,使中间道次钢丝达到最大抗拉强度,有利于减少后续道次的拉拔断丝现象。此工艺下的钢丝在拉拔后,在完成奥氏体均匀化后晶粒没有继续长大,既保证了钢丝组织的均匀,也防止了钢丝抗拉强度的降低。     

管线配套焊丝钢生产缓冷工艺研究

通过测定焊丝钢冷却过程连续过冷曲线,制定了管线配套焊丝钢盘条的冷却工艺。通过调整冷却工艺参数,使盘条强度满足了用户要求。拉拔试验结果表明,盘条可以不经过热处理直接拉拔到用户要求线径,拉拔后焊丝满足了用户缠绕与送丝要求。     

10.9级紧固件用非调质钢试制

 为开发高强度紧固件用非调质钢,在高速线材轧机上进行了试验轧制,并对试制产品的组织性能进行了检测。结果表明,在给定工艺条件下钢的组织基本上为粒状贝氏体组织,抗拉强度为897.5MPa,伸长率为21.8%。热轧材拉拔减面后达到或超过10.9级紧固件的力学性能要求。当拉拔量为25.0%时,可承受59.3%的压缩变形不开裂。     

拉丝断面压缩率对10B30钢球化退火组织及力学性能的影响

研究了拉丝断面压缩率(5%～35%)对Φ9.67～11.69 mm 10B30钢丝(/%:0.28～0.34C, 0.0005～0.0030B)球化退火组织及力学性能的影响。结果表明：随着球化退火前拉丝断面压缩率的增加,球化退火组织级别提高,抗拉强度降低,断面收缩率提高,这是因为拉丝促进了球化退火过程中的自发球化和碳化物的ostwald熟化;当拉丝断面压缩率达到25%以上,球化组织和相应的抗拉强度和断面收缩率趋于稳定;实际生产中,退火前拉丝断面压缩率不应低于25%。     

道次减面率配置对304H不锈钢丝拉拔过程中马氏体相变的影响

设计了两种不同的拉拔工艺(减面率/%:工艺一:34.45,31.67,19.00,20.08;工艺二:20.10,19.28,34.64,31.41),研究了道次减面率配置对304H不锈钢丝拉拔过程中马氏体相变、磁性能及力学性能的影响。结果表明:当钢丝总应变量相同时,大减面率配置在前更有利于马氏体转变,其饱和磁化强度更大,反之则马氏体转变量较少,饱和磁化强度较小。钢丝的强度与拉拔真应变呈线性相关,其大小只与拉拔总应变量相关。本试验中,前两个道次减面率为20.10%和19.28%,后两个道次减面率为34.64%和31.41%时,马氏体转变量较少,钢丝的饱和磁化强度较低。     

冷拔应变对304H钢丝扭转性能的影响

研究了 304H不锈钢丝Φ2.6 mm至Φ0.89 mm冷拔过程中组织演变和缺陷对不锈钢丝扭转性能的影响.结果表明:当钢丝冷拔真应变介于0～1.39时,扭转性能急剧下降、扭转次数减少;当冷拔真应变介于1.39～2.14时,扭转性能逐步回升,扭转次数增加.随着应变的施加,加工硬化导致位错塞积致使塑韧性变差,是扭转性能下降...     

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。     

提高硬线钢质量措施

对高碳钢盘条在拉拔过程中常出现的脆断现象进行分析,指出钢水纯净度不够、碳偏析、轧制过程冷却强度不够及风冷冷却不均是导致盘条在拉拔过程中发生断裂的主要原因。通过优化炼钢、轧钢工艺,提高盘条钢质量,降低并最终杜绝用户在使用过程中的断丝。     

高强度PC钢丝断裂原因分析及改进措施

对高强度PC钢丝断裂原因进行了分析,认为连铸坯的中心偏析、中心缩孔、疏松和夹杂是导致PC钢丝断裂的冶金原因;轧制过程中,较差的修磨质量、表面缺陷导致的微裂纹,过烧以及不适当的冷却速度导致的非正常显微组织,盘条头部的耳子、盘条本身折叠是导致PC钢丝断裂的主要原因;同时,不恰当的酸洗、较差的磷化及热处理质量、不适当拉丝裂纹的产生、拉拔模具安放不正导致的横裂也是PC钢丝断裂的原因。并且针对上述部分原因提出改进措施。     

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%。     

高强度大桥缆索用盘条生产现状分析

最近5年,大桥缆索用镀锌钢丝抗拉强度有了大幅提高,从1 770 MPa级、1 860 MPa级、1 960 MPa级到目前的2 000 MPa及以上级别,扭转指标有了颠覆性的改变,从之前的几转到目前的十几转、二十几转。论述了国内外钢铁企业生产大桥缆索镀锌钢丝用盘条的不同现状。从成分设计、生产工艺流程、盘条韧化处理方式和组织特点等方面进行阐述,讨论了国内外不同生产工艺特点及发展趋势,为中国大桥缆索镀锌钢丝用盘条的生产提供理论支持。     

Structure and Properties of Carbon Steel Wire in Drawing

A method of continuous deformational nanostructuring of wire is described. In the method, a continuously moving wire is subjected simultaneously to tensile deformation in drawing, flexural deformation on passing through a roller system, and torsional deformation. This combination permits wide variation in its mechanical properties, ensuring both high strength and plasticity. The benefits of such deformation are the use of a tool already employed in the production of metal components; compatibility with the speeds of coarse and moderate wire drawing; and simplicity of the equipment. Laboratory apparatus for this method is described. Carbon steel 50 wire is selected for investigation, since it in great demand. The chemical composition and mechanical properties of the wire in the initial state are described. Experiments are conducted to investigate the effectiveness of the proposed differential nanostructuring in producing ultrafine-grain structure in the wire. The deformation conditions of the wire are described, as well as the drawing process. The transverse and longitudinal microstructure of the carbon steel 50 wire at the surface and in the center after different types of deformational treatment is investigated. In the experiments, the influence of the type of deformational treatment on the microstructure of the steel and its anisotropy over the wire cross section is established. The compliance of the wire’s mechanical properties with current standards is verified. After all types of treatment, its mechanical properties are consistent with State Standard GOST 17305–91. Metallographic data and mechanical test results after combined deformational treatment indicate that such combinations of deformation provide a promising approach to creating ultrafine-grain structure in carbon wire.     

Production of ultra-high strength wire rod steels by vanadium microalloying

Ultra-high strength high-carbon wire rod steels have been produced using vanadium-microalloying technique instead of the conventional expensive and environment polluting lead patenting treatment. The strength increment attained in the hot rolled steels due to vanadium additions is maintained in the cold drawn wire. By using this technique, high tensile strength levels of 1550-1600 N/mm² were attained either by cold drawing of 0.17% V microalloyed high-carbon steel to 45-47% reduction or by cold drawing of 0.20% V microalloyed high-carbon steel to 25-30% reduction. An equation has been developed to predict the tensile strength from the chemical composition, cooling rate and reduction of area due to cold drawing. A combination of vanadium microalloying and accelerated cooling resulted in additional strength increment due to refining of microstructure and increasing the precipitation strengthening component. Inspite of the decrease in the amount of vanadium precipitates due to the increase in cooling rate, it is suggested that an increase in precipitation strengthening due to refining of these precipitates by accelerated cooling more than offsets the loss of precipitation strengthening due to decreasing the precipitates fraction.     

铅浴淬火工艺对70钢丝组织和性能的影响

研究了900℃均热+500℃铅浴54 s空冷处理对70钢(0.67%～0.75%C)Φ5.5 mm热轧钢丝经38.9%压缩率拉拔的冷拔钢丝组织和性能的影响。结果表明,500℃铅浴等温处理,该钢过冷奥氏体转变的孕育和转变时间最短,该钢丝抗拉强度提高了21.4%,伸长率提高9.5%,为随后通过细拉工艺进一步提高钢丝的综合力学性能建立了基础。     

钢丝拉拔过程损伤模型及模拟计算

  为研究材料拉拔成型过程中的损伤问题,以1860MPa级PC钢绞线为研究对象,运用损伤力学理论分析了钢丝拉拔成形过程,采用ABAQUS软件建立了钢丝拉拔成形过程的材料损伤有限元模型,并利用该有限元模型计算了拉拔形变过程中材料损伤的演化规律。计算结果表明,钢丝经单道次拉拔形变后,材料损伤值呈周期性分布,其损伤最大值始终出现在某几个节点上。随着形变量增加,钢丝损伤值也逐渐增加,从第1道次的0.0034逐渐增加到第8道次的0.0136,但增加的幅度逐渐减小。对于模具顶角为8°钢丝拉拔,单道次压缩率为16%～18%,损伤分布也较均匀,最大损伤值也较小。     

电梯用含氮节镍奥氏体不锈钢QN1701的组织和性能

借助Thermo-Calc热力学相图计算软件,开发了用于电梯的含氮节镍奥氏体不锈钢QN1701(12Cr17Mn7Ni2Cu2N),以代替443(019Cr21CuTi)超纯铁素体不锈钢。通过OM、SEM和电化学工作站等方法研究了QN1701和443不锈钢的组织及性能。N原子起着间隙固溶和细晶强化的作用,使QN1701不锈钢的屈服强度提高至400 MPa以上,达到443不锈钢的1.32倍。QN1701不锈钢的点蚀电位为241 mV,低于443不锈钢的289 mV,但其点蚀速率为9.10 g/(m2·h),低于443不锈钢的14.58 g/(m2·h)。在电梯用研磨拉丝表面状态下,QN1701不锈钢在质量分数为10%NaCl中性盐雾和干湿循环盐雾等加速腐蚀试验中的耐蚀性能均优于443不锈钢。分析发现,443不锈钢添加一定量的Nb、Ti稳定化元素所生成的(Nb,Ti)(C,N)析出相经研磨拉丝处理后,暴露于表面或被拖拽后留下微坑,导致其耐蚀能力急剧下降。综上所述,相较443不锈钢,QN1701不锈钢具有强度更高、伸长率更大和在研磨拉丝表面状态下耐蚀性更好等特点,这对于电梯轻量化设计和长寿命具有重要价值。     

硬线钢拉拔断裂机理及连铸工艺优化

 硬线钢除了要求良好的力学性能,还要求良好的加工性能,但硬线钢盘条在拉拔过程中常发生断丝,给加工的连续性带来巨大危害。为了减少硬线钢的拉拔断丝,对其拉拔断裂机理进行了研究,并开展了相应的连铸工艺优化。首先对82B硬线钢拉拔断丝试样进行了分析,通过对断裂试样的断口和纵剖面分析,结合对应的连铸坯内部质量检测,得出连铸坯中心缺陷及偏析对硬线钢拉拔断裂的影响机制为促进了盘条中心渗碳体膜的生成,导致了裂纹的产生和扩展。然后通过施加电流为350 A、频率为6.0 Hz的连铸凝固末端电磁搅拌,降低浇铸时钢水过热度至30 ℃以下等措施,82B硬线钢连铸坯中心缩孔和中心偏析度分别降低至0.5级和1.08以下,82B硬线钢拉拔断丝率由优化前的10~15 次/百t显著下降到4~5 次/百t。     

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。     

70钢盘条拉拔断裂的原因分析

70钢盘条在拉拔时发生断裂,经对盘条拉拔工艺和盘条材质进行分析,认为盘条心部存在网状渗碳体是造成拉拔断裂主要原因.     

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.