共查询到18条相似文献,搜索用时 156 毫秒
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采用不同的点焊工艺参数对研发的1700MPa级Si-Mn系热成形淬火钢板与低碳钢板DC04进行异种材料之间点焊,并对焊接接头的拉伸性能、显微硬度分布及微观组织特征等进行了分析。结果表明,焊接电流对点焊接头熔核直径和抗剪强度具有显著的影响,而焊接时间的影响相对较小。超高强度钢板侧的热影响区存在两个明显的软化区和硬化区,即在靠近母材处存在一个硬度明显低于母材的软化区,其组织为回火马氏体;在靠近熔核处存在一个硬度明显高于母材的硬化区,其组织为细小的马氏体。点焊接头熔核部位为柱状粗大马氏体组织,其硬度明显低于超高强度钢板母材且远高于低碳钢板母材。低碳钢板热影响区低的硬度和明显粗化的铁素体组织,使得点焊接头单向拉伸时均从低碳钢板的热影响区一侧破断。 相似文献
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安装在车门内的防撞梁是提高轿车侧碰撞安全性的关键部件,国外高安全性轿车都用超高强度钢板制造防撞梁,但超高强度钢板成形困难,普遍采用成本高的加热成形方法.笔者绍了采用有限元分析软件Dynaform对某高级进口型轿车超高强度钢防撞梁热成形改冷冲压工过程进行模拟仿真,并优化成形工艺,主要研究了温度对超高强度板内部组织变化起的作用.通模拟和实际对比研究工艺补充面对零件成形及回弹的影响,并设置凸顶得到了优化的工艺型面,同类相关高强度钢零件的生产起到了指导作用. 相似文献
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用热冲压模具研究了超高强度钢30CrMnSi2Nb热冲压配分工艺,测试了两步法淬火和配分处理工艺对超高强度钢的组织演变和强塑性能的影响规律。利用光学电镜(OM)、扫描电镜(SEM)进行了微观组织观察,用X射线衍射仪(XRD)研究了残余奥氏体含量的变化规律。结果表明:热成形配分工艺可明显提高钢的塑性和强塑积;配分过程中,碳配分和均匀化在几十秒内可完成;残余奥氏体含量是决定淬火马氏体钢塑性的主要控制因素。证实了热冲压淬火和配分工艺是一种可获得超高强度兼具高塑性汽车钢板的新型热成形处理工艺。 相似文献
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随着汽车轻量化的发展,迫切需要在不降低汽车零部件性能的前提下,开发一些新工艺来减轻零件的重量。钢板热冲压是一种将先进高强度钢板加热到奥氏体温度后快速冲压,在保压阶段通过模具实现淬火并达到所需冷却速度,从而得到组织为马氏体、强度在1 500MPa左右的超高强度零件的新型成形技术。对钢板热冲压新技术的关键装备、核心技术和优缺点以及使用现状等做了系统介绍,并预测了热冲压技术的未来发展趋势。 相似文献
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出于节能减排、增加燃油经济性和满足日益严厉的安全法规的需要,超高强度钢热冲压成形零部件在汽车上身的应用比例逐年增加。详细介绍了22MnB5钢热冲压工艺参数的设计规范,及裂纹失效问题的控制。为保证淬火后零件微观组织中马氏体含量≥95%,抗拉强度≥1 500 MPa的要求,奥氏体化加热温度应控制在900~950℃、淬火冷却速度≥30℃/s;模具设计时需进行导热量计算及导热系统结构设计,保证热冲压零件的成形减薄率<15%、弯曲角圆弧半径R≥13 mm;为抑制应力集中导致的开裂,系统导热量在整个零件表面分布应均衡一致,导热水管外壁距模具型腔表面的垂直散热距离应均匀一致为10 mm,零部件热处理后显微组织中应减少马氏体粗大化,避免混晶。 相似文献
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为了提高热成形钢的综合性能,设计了一种C-Si-Mn-Cr-B系热成形钢,采用热膨胀仪测定并研究了30SiMnCrB5热成形钢的连续冷却转变曲线和相变规律.分析了经轧制、退火及热成形模拟后钢板的微观组织形貌和力学性能,结合等密度线极图的方法,判定了热成形模拟后钢板中马氏体变体与母相的取向关系.30SiMnCrB5热成形钢具有较好的淬透性,临界冷速为5℃·s-1,有效抑制了珠光体和贝氏体的形成,完全马氏体组织的硬度可达600 HV以上.热成形模拟后的微观组织由板条马氏体和残余奥氏体构成,残余奥氏体主要以薄膜状分布在马氏体板条间,质量分数为6%~8%,抗拉强度为1800 Mpa左右,总伸长率可达10%以上,强度和塑性的匹配较好.热成形模拟后30SiMnCrB5热成形钢板中马氏体变体与母相的取向关系更接近N-W关系,12种变体没有都出现在原始奥氏体内. 相似文献
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Cold forming of high strength materials is accompanied by an undesirable spring-back effect and therefore the automotive industry prefers to produce components from high strength steels by hot stamping.Hot deformation and cooling in a die are applied to obtain shaped components with martensitic microstructure and high yield strength and ultimate tensile strength.This article presents new applications of this forming technology by incorporating another innovative heat treatment by the Q-P process,which improves both strength and ductility of obtained structures at the same time.Ultimate strengths over 2000 MPa with ductility above 10% can be achieved by this processing.To test microstructure development,thin sheet was hot formed and a corresponding FEM simulation was created.This processing was applied to low alloyed AHS steel with 0.42% of carbon and with an alloying strategy based on Mn,Si and Cr.Martensitic microstructure with retained austenite was obtained by this processing with a strength of around 2000 MPa and ductility of 10%. 相似文献
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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。 相似文献
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热成形零件已在汽车安全件上广泛应用,为了进一步提升零件碰撞安全性、提高表面质量、降低成本,基于中锰钢提出了一种降低加热温度的热成形技术,通过将完全奥氏体化的中锰钢在模具中淬火成马氏体组织获得超高强度力学性能,与22MnB5钢热成形相比,在获得1 500 MPa抗拉强度时,中锰钢温成形的加热温度可降低150 ℃以上,断后伸长率提高30%以上,同时提高零件的表面质量。综述并评价了中锰钢经温成形后的微观组织与力学性能以及冷弯性能、成形性能、电阻点焊等工艺性能,并与22MnB5钢热成形进行了系统地比较,体现出温成形中锰钢节能环保、提高碰撞安全性的技术优势。 相似文献
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Austempering of Hot Rolled SiMn TRIP Steels 总被引:2,自引:1,他引:1
The austempering after hot rolling in hot rolled Si Mn TRIP (transformation induced plasticity) steels was investigated. The mechanism of TRIP was discussed through examination of the microstructure and the mechanical properties of this kind of steel. The results showed that the strain induced transformation to martensite of retained austenite occurs in hot rolled Si Mn TRIP steels. The sample exhibited a good combination of ultimate tensile strength and total elongation when it was held at the bainite transformation temperature after hot deformation. The stability of retained austenite increases with an increase in isothermal holding time, and a further increase in the holding duration resulted in the decrease of stability. The mechanical properties were optimal when holding for 25 min, and tensile strength and total elongation reached the maximum values (774 MPa and 33%, respectively). 相似文献
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Hot stamping has been widely used in car industry to produce safety components.Most existing researches focused on the stamping and quenching process,but less on the mechanical properties of stamped parts.The fracture behaviors of hot stamped boron steel B1500 HS have been studied,and other four commonly used sheet metals with different strengths,including Q235,TRIP780,QP980 and MS1300,were also introduced for comparison.Both uniaxial tests and mechanical trimming tests were performed,and the fracture surfaces under different stress states were observed and discussed.The SEM observations showed that the fracture models are closely related to the stress states,i.e.,the tensile surfaces have ductile rupture characters while the trimming surfaces have brittle rupture characters.Compared with other steels,the quenched boron steel has smaller dimple size accompanied by shear planes in the tensile surface,and has smaller burnish zone in the trimming surface,and its cutting surface with‘S'like shape is also very different with others.Furthermore,two fitted empirical models were derived to describe the quantitative correlations between the average dimple diameter and the steel strength and between the percentage of burnish zone and the steel strength. 相似文献
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Hot stamping is a technique to produce ultra high strength automobile components. The common material used in hot stamping process is coated and/or uncoated 22MnB5 boron alloyed steel. Ferritic‐pearlitic microstructure in as‐delivered sheets is transformed to fully lath martensitic after hot stamping. In the present research, hot stamping under water or nitrogen cooling media was investigated using different boron alloyed steel grades. Microstructural analyses, linear and surface hardness profiling as well as tensile tests of hot stamped samples were performed. Various microstructures of fully bainitic and/or fully martensitic were produced. The resulting microstructures provided yield strengths of 650–1370 MPa and tensile strengths of 850–2000 MPa. There is an optimum carbon equivalent content for which the highest formability index value, UTS × A25, is achieved. Using a nitrogen cooled punch resulted in higher yield strength without significant changes in ultimate tensile strength. It is concluded that a wide range of B‐bearing steels having an extended carbon equivalent range with an acceptable formability index value can be used by increasing the cooling rate in the die assembly. 相似文献