宝钢开发出为汽车“减重节能”的热镀锌TRIP钢

日前，宝钢成功开发出热镀锌TRIP钢板。热镀锌TRIP钢又称为热镀锌相变诱发塑性钢，兼有高强度和高延伸率，是应对汽车“减重节能”所用高强度钢板中的一种。自2002年宝钢实现600兆帕级别冷轧TRIP钢的产业化后，研究院汽车用钢研究所克服了诸多困难，在国内率先成功试制出强度级别为600兆帕的热镀锌TRIP钢，产品实物性能达到国际同类产品水平。     

低碳相变诱发塑性钢的综合性能

对抗拉强度600 MPa级的低碳相变诱发塑性钢(TRIP钢)进行了拉伸、成形、高速冲击拉伸和激光焊接试验.对焊接前后的综合性能进行了对比,并对其金相组织、显微硬度进行了观察和测试分析.与原始板材相比,激光焊接后,低碳TRIP钢的强度和硬度增加,而伸长率略有下降;焊接热影响区的硬化较明显,但均未发现明显的焊接裂纹及其它缺陷,表明其焊接性能良好.发现低碳TRIP钢成形性能、抗凹陷性能、激光焊接性能良好.     

TRIP-相变诱发塑性钢的研究进展

相变诱发塑性钢是一种汽车用钢，通过相变诱发塑性(TRIP)效应使钢板中残余奥氏体在塑性变形作用下诱发马氏体生核和形成，并产生局部硬化，继而变形不再集中在局部，使相变均匀扩散到整个材料以提高钢板的强度和塑性。典型TRIP钢c含量为0．2％，Mn 1％～2％，Si 1％～2％，通过热轧变形热处理或冷轧 热处理，TRIP钢的组织由50％～60％铁素体，25％～40％贝氏体或少量马氏体和5％-15％残余奥氏体组成。TRIP钢的强度和韧性高于双相钢和微合金钢。介绍了TRIP钢的生产工艺和性能，残余奥氏体、合金元素、热处理对TRIP效应的影响和TRIP钢研究趋势。     

学术团体要做好保障为科技人员解除后顾之忧

蒂森·克虏伯公司除了生产冷轧双相钢（DP）,残留奥氏体钢（RA）或相变诱导塑性钢（TRIP）外,目前还在生产经过热轧的热镀锌复杂相钢（complex phase钢,cp）。这些钢种与传统钢种相比,特别是与Al和Mg合金相比,具有优越的强度和延展性综合性能,     

相变诱导塑性汽车用钢的发展现状与趋势

论述了相变诱导塑性(TRIP)钢的发展现状及其在汽车工业上的应用,重点讨论了 TRIP 效应的机理及TRIP钢性能的影响因素。介绍了2种采用新型工艺(低温贝氏体转变和淬火-碳分配工艺)的 TRIP 钢,并且通过对TRIP钢研究的最新数据,对比了2种工艺下TRIP钢的高速拉伸性能;最后对汽车用 TRIP 钢的研究方向进行了展望。     

鞍钢先进高强汽车用钢的研制开发

介绍了鞍钢先进高强汽车用钢开发研制情况,包括以980 MPa级DP钢、TRIP钢、TWIP钢和QP钢为代表的热轧、冷轧和热镀锌先进高强钢系列产品,以及鞍钢开发的先进高强钢热镀锌生产技术,并对鞍钢先进高强汽车钢未来的发展方向进行了展望。     

基于动态相变的C Si Mn系热轧相变诱导塑性钢

 利用热模拟压缩变形,扫描电子显微镜(SEM),X射线衍射(XRD)以及金相实验,探讨了用过冷奥氏体动态相变控制低碳硅锰系相变诱导塑性(TRIP)钢组织的工艺过程,并初步研究了不同工艺条件下组织与性能的关系。结果表明：采用过冷奥氏体动态相变工艺控制TRIP钢的组织是可行的,用相应工艺得到的TRIP钢的抗拉强度达到Rm=900 MPa,伸长率A=24%。     

超轻汽车车体用钢热镀锌的研究及应用现状

综述了超轻汽车车体用钢热镀锌的研究及应用现状,重点介绍了烘烤硬化钢、高强度IF钢、双相钢、相变诱导塑性钢等热镀锌的生产工艺和性能影响因素。     

技术信息

·国内·宝钢国内独家开发成功冷轧 TRIP钢COL D ROL L ED TRIP STEEL BAOSTEELHAS DEVEL OPEDTRIP钢即相变诱导塑性钢 ,宝钢开发成功的 TRIP钢 ,强度级别为 6 0 0 MPa。因这种车板强度高 ,大致能使车身减薄 10 %～ 2 0 % ,从而减少了车中和车身成本 ,亦降低了油耗 ,为打造减轻环境污染的“环境友好车”创造了良好条件。这种 TRIP钢 ,与其他同级别的高强度钢相比 ,最大特点是兼具高强度和高延伸性能 ,可冲制较复杂的零件 ;还具有高碰撞吸收性能 ,一旦遭遇碰撞 ,会通过自身形变来吸收能量 ,而不向外传递 ,常用作汽车…     

残余奥氏体对TRIP钢机械性能的影响

简要介绍了TRIP(transformation induced plasticity, 相变诱导塑性)钢中残余奥氏体的形成及其微观组织形貌,综合阐述了残余奥氏体对TRIP钢性能的影响,并由此提出对TRIP钢进一步改善的途径.     

高强钢板热镀锌工艺研究现状

介绍了高强度镀锌板的研究现状,重点阐述了DP、TRIP、TWIP钢的研究概况及镀锌工艺对其性能的影响;最后进一步简单介绍了热镀锌钢镀层性能的要求(包括耐蚀性、成形性等).     

Advanced Cold Rolled Steels for Automotive Applications

Advanced high‐strength steels offer a great potential for the further development of automobile bodies‐in‐white due to their combined mechanical properties of high formability and strength. They represent the first choice in material selection for strength and crash‐relevant parts with challenging geometries. The intensive development of multiphase steels by ThyssenKrupp Steel has led to hot dip galvanizing concepts with an outstanding forming potential. Hot rolled, hot dip galvanized complex‐phase steels are currently produced in addition to cold rolled dual phase (DP) and retained austenite (RA) or transformation induced plasticity (TRIP) steels. New continuously annealed grades of steel are being developed with tensile strength levels of up to 1000 MPa in combination with sufficient ductility for the high demands of structural automobile components. These steels make use of the classic advantages of microalloying as well as the principles of DP steels and RA / TRIP steels. Further improvement of properties will be reached by the new class of high manganese alloyed steels.     

汽车钢板点焊工艺的发展

通过文献调研分析了冷轧、镀锌及高强汽车板的焊接特点。采用普通点焊工艺,铁锌合金镀锌板比纯镀锌板点焊工艺窗口宽约30%,但预热后纯镀锌板焊接性能较好;FEA模拟Mn-Si系TRIP800钢的焊点十字拉伸强度明显高于Mn系DP450钢,但实际试验结果却明显较低;Mn系1.5mm规格的DP800钢在点焊电流11 000A及时间0.6s时,焊点拉剪试验以韧性特征为主,焊点拉剪力高于20kN。1 300MPa热成型钢点焊接头有一定软化倾向。不同种类高强钢的合金元素含量和生产工艺的不同,其焊接性能体现出较大差异。     

固溶温度对中锰TRIP钢组织与力学性能的影响

以w(Mn)=8%的热轧TRIP钢(即相变诱导塑性钢)为对象,研究了热处理工艺对其显微组织与力学性能的影响规律.该中锰TRIP钢在固溶温度为800℃时,可获得包括铁素体、马氏体、残余奥氏体的多相组织.与一般TRIP钢相比,其力学性能明显提高,在固溶加回火的条件下,实验钢的抗拉强度为800～1 000 MPa,延伸率达到31%～40%,而强塑积达(30～32)GPa%.     

Strain Hardening and Strain Rate Sensitivity Behaviors of Advanced High Strength Steels

 The mechanical properties of commercial dual phase (DP), transformation induced plasticity (TRIP), and high strength low alloy (HSLA-340) steel sheets are investigated and compared at various strain rates ranging from 0. 0017 to 0. 17 s-1 at ambient temperature. TRIP steel outperforms the other two materials, having comparable ductility and twice as large strength relative to DP steel. TRIP has larger strength and much larger ductility than HSLA-340. The exceuent ductility of TRIP800 is due to its high strain hardening capability, which promotes stable plastic deformation. It is observed that the strain hardening rate in TRIP800 does not decrease to zero at failure, as common in most materials in which failure is preceded by necking.     

New thermomechanical strategy for production of high strength low alloyed multiphase steel showing transformation induced plasticity effect

Abstract

In the past few years a lot of research was carried out on the development of transformation induced plasticity (TRIP) assisted multiphase steels. Two principal ways were proposed: (i) controlled cooling during the hot rolling process to obtain hot rolled TRIP assisted multiphase steels and (ii) the combination of intercritical annealing and isothermal holding at bainite formation temperatures during continuous annealing resulting in cold rolled TRIP assisted steel products. Unfortunately, both thermomechanical methods proposed require a high silicon level to inhibit cementite precipitation to avoid a loss of stability for the metastable retained austenite. In addition, due to high silicon levels, red scale surface defects appear and only moderate hot dip galvanisability is possible. In this paper a new thermomechanical strategy for the production of high strength low alloyed TRIP assisted multiphase steels with good hot dip galvanisability and without red scale defects will be presented.     

Influence of post-weld heat treatment on the microstructure and hardness of laser weld seams on hot-rolled TRIP 800 steel

The transformation induced plasticity (TRIP) steels effect occurs because of the martensitic transformation of retained austenite during plastic deformation,and it provides the steel with excellent strength and ductility.While welding remains a vital part of auto body manufacturing,the weldability of TRIP steels is problematic,and this prevents its adoption for many applications in the automotive industry.This present work studies the effects of welding and post-weld heat treatment on the microstructure of TRIP steels.It is found that the microstructures of the fusion zone and the heat affected zone (HAZ) are changed after high-temperature heat treatment.Hardness tests revealed that fusion zone hardness decreased with increasing of temperatures in the post-weld heat treatment on the laser weld seam.The rolling performance of the welding seam and the seam of post-weld heat treatment were also studied.     

Development of Ultrahigh Strength TRIP Steel Containing High Volume Fraction of Martensite and Study of the Microstructure and Tensile Behavior

A new transformation induced plasticity (TRIP) steel containing high volume fraction of martensite was produced by austempering heat treatment cycle. Microstructure and tensile properties of this TRIP steel were investigated and compared to those of a dual phase (DP) steel with high martensite volume fraction. Microstructural analysis showed a mixture of ferrite, bainite, retained austenite and about 25–30 vol% of martensite in the TRIP steel. As a result of the strain induced transformation of retained austenite to martensite, the TRIP steel showed a strength elongation balance of 86% higher than that for the DP steel. In comparison to the commercial TRIP780 steel, the current TRIP steel showed a 15% higher ultimate tensile strength value while maintaining the same level of ductility. TRIP steel also had a larger work hardening exponent than DP steel at all strains.     

Effect of Cooling Method on Microstructure and Mechanical Properties of Hot-Rolled C-Si-Mn TRIP Steel

 The controlled cooling technology following hot rolling process is a vital factor that affects the final microstructure and mechanical properties of the hot-rolled transformation induced plasticity (TRIP) steels. In the present study, low alloy C-Si-Mn TRIP steel was successfully fabricated by hot rolling process with a 450 hot rolling mill. To maximize the volume fraction and stability of retained austenite of the steel, two different cooling methods (air-cooling and ultra-fast cooling “AC-UFC” and ultra-fast cooling, air-cooling and ultra-fast cooling “UFC-AC-UFC”) were conducted. The effects of the cooling method on the microstructure of hot-rolled TRIP steel were investigated via optical microscope, transmission electron microscope and conversion electron Mssbauer spectroscope. The mechanical properties of the steel were also evaluated by conventional tensile test. The results indicated that ferrite and bainite in the microstructure were refined with the cooling method of UFC-AC-UFC. The morphology of retained austenite was also changed from small islands distributing in bainite district (obtained with AC-UFC) to granular shape locating at the triple junction of the ferrite grain boundaries (obtained with UFC-AC-UFC). As a result, the TRIP steel with a content of retained austenite of 1152%, total elongation of 32% and product of tensile strength and total elongation of 27552 MPa·% was obtained.