Structure and properties of nickel-molybdenum steel wire rod after thermomechanical treatment

The mechanical properties and structure of low-carbon nickel-molybdenum steel wire rod after softening thermomechanical treatment in a high-speed wire mill are studied. Dislocations may move through insular martensite and bainite sections of the structure under the action of deformation. Good plasticity of wire rod in deformational shaping may be ensured by the presence of a small proportion (up to 10%) of sections with bainite-martensite structure and the motion of dislocations through those sections.     

High-carbon wire rod made of steel microalloyed with vanadium

The Moldavian Metallurgical Combine has mastered the production of quality vanadium-bearing high-carbon wire rod 5.5–12.0 mm in diameter. Strengthening of the grain boundaries of the steel and its dispersion-hardening significantly increase the strength properties of wire rod made of steel that has been microalloyed with vanadium, while the ductility of the product also remains high. Tests in which vanadium-bearing high-carbon wire rod 5.5–12.0 mm in diameter was drawn into 3–7-mm-diam. wire were conducted at hardware plants and showed that the wire rod is well-suited for the production of wire used in the reinforcement of prestressed concrete structures.     

High-deformability wire rod made of steel Sv-08G2S

Welding wire is made with the use of wire rod composed of steels Sv-08G2S, Sv-08G1S, and SG-1, 2, 3. A new technology that has been developed to obtain this product provides for mechanical scale removal, dry drawing of the wire rod to an intermediate diameter of 1.7–2.2 mm, then — without an intermediate heat treatment — wet drying combined with electrochemical copper-plating of the wire surface. The diameter of the wire is 1.6—0.8 (0.6) mm. The advantages of the new technology for making welding wire are obvious: a reduction in production cost due to the elimination of pickling and heat treatment for the rod; an improvement in the environmental situation at the manufacturing plant. __________ Translated from Metallurg, No. 2, pp. 64–70, February, 2007.     

Ensuring high quality indices for the wire rod used to make metal cord

Mastering the production of high-carbon wire rod — especially cord-grade wire rod — on a mini-complex originally built at the Moldavian Metallurgical Plant to make ordinary wire rod was a daunting problem that has been solved by a collaboration with the Ukrainian Academy of Science’s Institute of Metallurgy. Researchers developed an integrated technology for making the steel, continuous-cast semifinished products, and wire rod needed to make metal cord of ordinary, high, and ultrahigh strength. The wire rod is characterized by a good-quality surface (defect depth no greater than 0.15 mm, with 95% being no deeper than 0.10 mm), good deformability, and the ease with which it can be converted into wire, strands, and cord structures.     

氧含量对硫系易切削钢Y1215中硫化物的影响

研究了T[O]0.0074%～0.0145%对Y1215易切削钢(/%:0.05～0.06C,0.008～0.010Si, 1.26～1.27Mn, 0.049～0.051P,0.37～0.39S)160 mm×160 mm铸坯中硫化物夹杂的分布、尺寸、形貌的影响和轧制Φ8.0 mm热轧盘条中硫化物的变形情况。结果表明：随着氧含量增加,铸坯中硫化物夹杂的尺寸和分布无明显区别,但复合夹杂物数量明显增多,复合型的夹杂物有以MnS为核心包裹或附着MnO-SiO₂和以MnO-SiO₂-Al₂O₃为核心附着MnS夹杂物。在轧制Φ8.0 mm的盘条中,T[O]为0.0074%时,盘条中硫化物变形明显,部分硫化物由于拉伸变形严重而碎断,硫化物的长宽比为23.2,T[O]为0.0145%时,盘条中硫化物沿轧制方向变形小,主要以纺锤形为主,硫化物的长宽比为3.4。为获得球形或纺锤形的硫化物,冶炼时Y1215钢中的T[O]可控制在0.0095%～0.0145%。     

Wire rod of boron-bearing low-carbon steel for direct deep drawing

The Moldavian Metallurgical Plant has developed an integrated technology for making steel, a continous-cast semifinished product, and wire rod in accordance with the requirements of international standards. The technology involves optimizing the chemical composition of the steel (normalizing the contents of the chemical elements and the carbon equivalent C _e , inoculating the steel with calcium to lower its content of nonmetallic inclusions, and microalloying it with boron) and using efficient regimes for rolling and two-stage cooling (thermomechanical treatment) of the wire rod on a Stelmore line. The low-carbon wire rod is easily cleaned of scale by mechanical or chemical means and can be reduced from 5.5 to 0.5 mm in diameter by drawing at speeds up to 30 m/sec without an intermediate heat treatment to soften the wire rod/wire.     

马氏体钢40Crl0Si2Mo线材表面裂纹原因分析和工艺改进

40Cr10Si2Mo钢Φ6.5mm线材产品经过调质处理和矫直研磨后,发现磨光棒表面存在表面裂纹。通过进行40Cr10Si2Mo钢淬火回火模拟试验,得出造成40Cr10Si2Mo钢线材表面出现裂纹的原因为线材热轧后冷却时间短,冷却速度快,热轧线材表面存在较大的残余应力,从而形成表面裂纹。通过对40Cr10Si2Mo钢的生产工艺进行了优化改进,包括延长斯太尔摩辊道缓冷时间,终轧温度和吐丝温度由原来的900～950℃和850～900℃均调整为800～850℃,线材轧制后24 h内退火,从而避免了40Cr10Si2Mo钢线材表面裂纹的产生。     

汽车发动机气门挺柱用16MnCr5冷镦钢盘条的研发与生产

汽车发动机气门挺柱用冷镦钢16MnCr5生产流程为80t 顶底复吹转炉→LF+RH精炼→325 mm×280 mmm大方坯连铸→高速线材轧制。通过采用碱度4.8的精炼渣（/%:54.5CaO,28.5Al₂O₃,11.2SiO₂,6.2MgO,0.6FeO+MnO）、取消钙处理工艺、铸坯表面淬火技术、精轧温度880～900℃、卷取温度850～870℃等工艺,成功开发出16MnCr5钢。检验结果表明,生产的Φ30 mm盘条金相组织为均匀的铁素体+珠光体,晶粒度8级,断面收缩率71.1%～72.5%,1/3冷镦合格;氧含量0.0010%～0.0012%,N含量0.0045%～0.0047%,夹杂物尺寸均在10μm以内,无Ds类夹杂,夹杂物类型主要为单一的镁铝尖晶石夹杂。盘条具有良好的塑性变形能力和较高的纯净度,满足了客户的要求。     

南钢转炉流程生产高品质帘线钢的实践

介绍了南钢第二炼钢厂帘线钢NLX82A盘条的工艺情况。通过转炉出钢硅锰复合脱氧、精炼造酸性渣、优化连铸二冷参数,有效控制了钢中非金属夹杂物的含量及塑性转变,缓解了连铸方坯碳偏析。结果表明,铸坯平均总氧质量分数为0.002%,氮质量分数控制在0.004%左右,钢中铝、钛质量分数均低于0.001%,显微夹杂物均符合标准要求,中心碳偏析指数控制在1.1以下,表面无脱碳层,氧化铁皮易于脱离。其综合质量通过了重点用户的专业测评,盘条拉至0.25 mm,经捻制合股后完全满足钢帘线使用要求。     

铬合金化对C82D2Cr钢帘线盘条组织和性能的影响

在保证[Mn]+[Cr]含量0.5%～0.6%前提下,将Mn含量由0.50%降低到0.24%,Cr含量由0.021%提高到0.32%,以保证C82D2Cr钢淬透性,获得更高强韧性。结果表明：与C82D2钢Φ5.5 mm盘条相比,C82D2Cr钢Φ5.5 mm盘条抗拉强度提高50 MPa,断面收缩率提高4%,索氏体片层间距降低9.8%,珠光体团尺寸降低了14.5%;C82D2Cr钢不仅铁素体与渗碳体的界面处位错线明显,而且铁素体内的位错线密度增高、位错胞数量较多,可显著增加形变强化能力。经客户验证,C82D2Cr钢盘条可以满足2×0.30UT规格钢帘线的生产要求。     

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。     

冷却强度对超高硫中碳钢方坯凝固过程MnS生长的影响

 中碳超高硫易切削钢SAE144是兼具力学性能与切削性能的结构钢,用于制造汽车发动机密封阀件等,产品多采用转炉/电炉→LF精炼→连铸小方坯→线棒材热轧→冷拉及机加工成型流程生产,近年来市场热度稳步提升。若钢中MnS尺寸过大,零件加工使用过程易发生探伤不合、切削性能差、带状组织严重、力学性能各相异性显著,甚至拉拔加工断裂等问题。MnS夹杂物多在铸坯凝固后期形成,随着轧制与钢基体同步变形,控制该类钢种铸坯内MnS原始尺寸成为控制热轧材中MnS夹杂物形态及尺寸的最关键环节。为控制热轧超高硫中碳钢盘条中MnS夹杂物,利用钢坯凝固数值模拟、第二相析出理论、Ostwald熟化理论计算分析了160 mm2钢坯中硫元素偏析及MnS的生成、长大和熟化过程。计算结果表明,当固相分数f_s为0.446、硫微观偏析比达到2.19时,铸坯在凝固末期生成MnS。凝固过程中MnS的生长过程决定了钢坯中MnS颗粒的直径。理论计算表明,当连铸二次冷却水量固定为0.6L/kg时,拉速为1.6、2.1和2.6 m/min时,160 mm2方坯中心的MnS分别增长到30.6、32.2和34.6 μm,与实际测试结果一致。控制该类钢种线材中MnS尺寸的关键是提高二冷区的冷却强度,降低连铸拉速。基于该系列计算方法,提出了160 mm2钢坯中与MnS直径控制目标相匹配的连铸工艺参数控制范围。     

Thermomechanically treated high-carbon wire rod for high-tension wire

In twist tests of high-tension bronzed wire (diameter 1.55–1.83 mm) produced by direct drawing from thermomechanically treated wire rod (diameter 5.5 mm), lamination of the metal may be completely eliminated if the carbon and manganese content is reduced and chromium is added.     

Present situation and countermeasure of low-alloy spring steel wire rod for domestic automobile

The variety,inner quality and surface quality of low-alloy spring steel wire rod for domestic automobile is summarized in detail.And according to commercial low-alloy spring steel wire rod variety, product quality level and its actual application situation on automobile supplied by present industrially developed country metallurgy enterprises,it is pointed that the variety of low-alloy spring steel wire rod for domestic automobile can’t satisfy the requirements of automobile industry development,compare with overseas advanced technology,product quality has the following gaps:the first is that steel purity is low,the control level of non-metallic inclusions is not steady,there is often large grain difficult deforming non-deformation inclusions existing,the control level of steel purity has big difference,the level of large steel factory is high,but its steady has a large gap compare with foreign advanced level,not to mention small steel factory which research and development powder is low.The second is surface complete decarburization can’ t be avoided completely.The third is that surface defects are more.The fourth is that composition segregation and structure segregation are not steady,steel wire can’t be drawn normally when the segregation is serious. In all,the segregation of 55SiCrA is superior to 60Si2MnA obviously.The industrialization of domestic high level low-alloy spring steel wire rod can’t seek quick success and instant benefits,independent innovation perseveringly must be adopted,the success may be reached after master core technologies and adopt the science way of step by step.     

热拔工艺对高氮无镍奥氏体不锈钢线材开裂的影响

在开发一种高氮无镍奥氏体不锈钢线材时,热拔线材表面出现了大量的裂纹。通过金相、扫描电子显微分析和能谱检测,对其开裂原因进行研究。发现线材的表面裂纹基本垂直于拉拔方向,裂纹在表面产生,之后向线材内部发展。线材表层存在着大量的富Cr和N的氮化物析出,沿晶析出的析出相,会导致孔洞形成,这些孔洞相连,形成微裂纹,最终导致沿晶开裂。通过加长加热区、提高拉拔速率保证了线材表面温度,避免了表面裂纹的产生,获得了质量满足要求的高氮无镍奥氏体不锈钢线材,并最终给出了建议的热拔工艺。     

奥氏体组织对低碳中锰钢冷弯性能的影响

摘要：采用冷弯直径0～60mm，弯曲角度180°，研究了20mm厚度低碳中锰钢的冷弯性能，冷弯后外表均无可见裂纹，判定合格。利用光学显微镜、扫描电镜、透射电镜、电子背散射衍射（EBSD）、X射线衍射仪等手段分析了显微组织，尤其是奥氏体组织在冷弯过程中对冷弯性能的影响。结果表明，冷弯前显微组织由板条马氏体和奥氏体组成，其中原始奥氏体晶界明显；冷弯直径为0mm变形后，样品弧顶部分奥氏体的体积分数由12.3%降至1.1%，维氏硬度由295HV1增至364HV1，晶粒尺寸由4.07μm增至4.30μm。主要原因是在冷弯过程在中奥氏体组织发生塑性变形，奥氏体晶界变形消失，沿冷弯方向呈拉伸带状组织形貌，冷弯形变时奥氏体发生TRIP效应显著。     

大规格高碳硬线82B拉拔脆断原因分析

采用金相组织检验分析等方法,分析了大规格82B拉拔劈裂脆断问题.结果表明:劈裂断口试样的中心处,由于锰、铬偏析而出现异常的马氏体组织,导致其变形与基体不一致,在拉拔过程中中心马氏体断裂成为裂纹源.断口附近表面存在结疤和擦伤等表面缺陷,中心马氏体和表面缺陷共同导致大规格82B拉拔劈裂脆断.通过优化合金元素锰、铬的成分含量...     

SWRCH35K钢盘条冷镦开裂分析与工艺改进

釆用光学显微镜对SWRCH35K钢冷徵开裂样品和Φ12 mm热轧盘条进行高倍检验。分析表明,冷镦开裂原因为热轧盘条表面存在完全脱碳层,导致强度下降,致使表层基体受冷锹成型过程中应力作用产生开裂。 通过将钢坯加热温度从原1000 ~1 150 °C降至950 - 1 050°C 空燃比控制在0.4-0. 6,总加热时间由原95 ~ 212 min降至95 - 158 min,有效消除了 SWRCH35K钢热轧盘条的完全脱碳层,避免了螺栓、螺母的冷镦开裂。     

基于热模拟试验的双相钢盘条热轧工艺设计

 采用Gleeble 1500热模拟试验机模拟了ER70S-6钢在高速线材生产中的精轧和冷却工艺,并根据模拟试验结果绘制了ER70S-6钢的动态CCT曲线图, 优化了获得双相组织的精轧和冷却工艺。结果表明,在845℃变形后以大于10℃/s冷速冷却,ER70S-6钢可以获得含约11%马氏体的双相组织;冷速大于30℃/s时变形组织的晶粒尺寸较小,约4. 2μm。变形后以大于30℃/s的冷速冷却,ER70S-6钢可以获得晶粒尺寸细小、马氏体含量稳定的双相组织。通过热模拟试验的指导,在高速线材轧机上成功生产出晶粒尺寸约8. 2μm、马氏体含量约11. 5%的双相组织盘条。     

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.