基于DEFORM软件的U型梁激光拼焊件热成形仿真分析

采用DEFORM软件对U型梁激光拼焊件进行计算机仿真,拼焊材料为热成形钢800HS与1500HS,研究热成形过程中温度场、相组成的变化过程,并对保压、模具间隙、冷却能力等热成形主要工艺参数对热成形效果的影响予以讨论,获得了全工序的温度场、相组成的变化规律,给出了热成形主要工艺参数对热成形效果的影响,其中模具间隙是决定热成形淬火性能的关键因素,冷却水道是保障连续模淬的关键措施。经实际生产验证,仿真分析符合性较好,对激光拼焊件热成形实际生产具有一定的指导意义。     

CR1 500HF热成形钢开发及应用

基于热成形钢成形过程和相变强化机理,设计合理的成分体系,并制定了相应的炼钢、轧制和退火等关键控制工艺,开发出1 500 MPa级热成形钢CR1 500HF。供货态抗拉强度600 MPa左右的微观组织(铁素体+珠光体组织)加热后转变为奥氏体组织,成形淬火后转变为1 500 MPa左右的马氏体组织,既保证了成形性,又保证了高强度零部件的尺寸精度。不同加热温度对力学性能的影响较小,加热工艺窗口较宽,合理的加热温度范围为825～950℃。最终选择合理的加热工艺试制出质量合格的B柱零部件。     

热冲压成形钢T1500HS重卷及退火工艺优化

介绍了热成形钢T1500HS的成分设计及工艺流程,指出了其在罩退、平整及重卷生产过程中存在的问题,并提出了相应的优化措施。通过调整平整工艺及焊接参数,钢卷的板形得到有效改善,生产速度由80 m/min以下提高到150 m/min,机时产量由1卷/h提高到1.5卷/h;通过优化罩退内圈焊接工艺,带头擦伤缺陷大大减少,废次降比例10%;通过执行相应规格的程度,产品力学性能有了较大改善,屈服强度降到了客户的要求值390～410 MPa。优化措施实施后,T1500HS钢质量有了较大提升,提高了市场竞争力。     

高强度桥梁钢Q500qE角焊缝焊接工艺研究

采用CO_2气体保护焊和埋弧自动焊进行高性能桥梁钢Q500qE熔透及T型角焊缝的焊接工艺试验,结果表明,焊接接头成形良好、机械性能达到要求,焊缝组织以针状铁素体为主,热影响区组织以贝氏体为主,保证了接头良好的强韧性。利用本试验焊接工艺焊接的角焊缝各项检验均合格,本试验焊接工艺及钢板、焊材可用于大跨度桥梁角焊缝的焊接施工。     

液压成形技术及其在汽车工业中的应用介绍

液压成形技术由于其出色的零件成形质量、相对简单的加工工艺,被广泛应用于汽车、航天航空等制造业。主要介绍了管材和板材液压成形的技术原理和特点、国内发展现状以及在汽车工业中的应用,同时也简要介绍了超高强钢液压成形技术在汽车零件制造方面的应用。液压成形技术虽具有一定优势,但在汽车板材成形和超高强钢零件的工业化生产方面还有待发展。     

热浸镀工艺对热成形钢铝硅镀层的影响

随着汽车轻量化的不断发展,热成形钢得到越来越快的发展,普通镀层已满足不了热成形工艺的要求。热浸镀铝硅钢板具有优良的耐热耐腐蚀性能、抗高温氧化性能和外观装饰性能等,得到普遍的应用。目前国内对铝硅镀层研究甚少,国内汽车制造厂使用的镀铝硅热冲压成形钢主要依靠进口。利用CAG-III热浸镀锌模拟试验机,针对不同热浸镀工艺对热成形钢板进行热浸镀铝硅试验,通过扫描电镜等手段进行表面和截面形貌观察及能谱分析。试验结果表明,铝硅镀层截面组织主要由铝基固溶体、Al-Fe-Si三元合金和Fe-Al二元合金组成,当浸镀温度为690 ℃、浸镀时间为5 s时为最优浸镀工艺。     

超高强度热成形钢研究进展及展望

在“双碳”战略的大背景下，环保、节能等问题越来越受到重视，由此对汽车用钢轻量化提出了更高的要求，超高强热成形钢作为汽车用钢的重要组成部分，有着广阔的研究前景。概述了国内外热成形钢研究现状，从成分设计、组织特征、工艺调控等多个角度出发，总结出了微合金化和残余奥氏体组织调控对超高强热成形钢强塑化机制的影响规律；阐述了铝硅镀层、锌基镀层热成形钢及新型无镀层高抗氧化性热成形钢的研究进展；论述了超高强热成形钢微观组织与氢致延迟开裂行为之间的相互作用。对超高强热成形钢的进一步优化控制提出了建议，为实现高强塑性及优异服役性能的超高强热成形钢的研发与产业化应用提供了参考。     

20CrMnTiH钢的热变形物理模型及三维加工图

随着精密成形技术的发展,对热锻工艺的要求越来越严格,采用建立材料的物理模型及热加工图这一方法来优化最佳工艺条件,为实现产品的质量精确控制提供了科学保障。通过Gleeble-3800热模拟试验机对20Cr Mn Ti H钢在变形温度为850~1 150℃,应变速率为0.01~10 s~(-1)条件下进行等温热压缩试验,研究了20Cr Mn Ti H钢的热压缩变形特性,采用Zener-Hollomon参数法建立了20Cr Mn Ti H钢高温塑性变形的物理模型;并以热压缩试验为基础,绘制了20Cr Mn Ti H钢的三维热加工图并进行分析,确定了该钢的最佳热成形工艺参数。通过流变曲线可以看出,20Cr Mn Ti H钢在热成形过程中发生了明显的动态回复与动态再结晶,流变应力随应变速率的增加而增加,随变形温度的升高而降低;由热加工图分析得到了该钢在试验参数范围内较优的热加工工艺参数,加工温度为900~1 025℃,应变速率为0.01~0.2 s~(-1)。     

500 MPa Nb-Ti微合金高强度汽车车轮钢510CL开发和使用性能

开发试验的 510CL 钢(/% ：0. 08C,0. 07Si,1.25Mn,0. 008P.0. 005S,0. 023Nb,0.018Ti)经半钢脱硫- 200 t顶底复吹转炉-LF-230 mm x 1 650 mm板坯连铸-连轧成5.0 mm板。为了保证车轮钢具有良好的焊接性能，釆用了低碳Nb-Ti微合金化,并结合TMCP(热机械控制轧制工艺)技术开发出500 MPa高强度车轮钢。试验钢的扩 孔率超过100%和焊接性能良好,其冷成形性能和疲劳寿命均达到用户的技术指标，使用后试验钢达到设计要求。     

700 MPa级热轧双相钢的组织和性能

 采用热模拟并借助光学显微镜、SEM技术研究了双相钢的相变规律及不同工艺参数下的组织演变规律。根据热模拟结果在实验室试制出700 MPa级热轧双相钢,优化了轧制和冷却工艺参数。实验结果表明：热轧双相钢组织为多边形铁素体+马氏体岛,抗拉强度730 MPa,屈强比062,伸长率236%,达到了DP700级双相钢的性能要求,并讨论了热轧卷取温度对双相钢最终力学性能的影响。     

Control over Mechanical Properties and Microstructure of BR1500HS Hot-stamped Parts

The hot-stamping processing parameters are of critical importance in transforming ultra-high-strength steel(UHSS)into high-quality parts,which were studied by mechanical properties tests,metallographic observations and calculation analysis method based on hot stamping experiments and numerical simulation technology,the mechanical properties,thickness,dimensional accuracy,and microstructure of the hot-formed parts are analyzed to determine the influence of different processing parameters for UHSS parts formed from BR1500HS.The results indicate that the quenching time had the most significant impact on the mechanical properties of the parts,and longer quenching time resulted in better mechanical properties.In addition,the pressing speed had a significant influence on the thickness of the formed parts,and the part-opening temperature had the most significant effect on the dimensional accuracy of the parts.And to get hot-stamped parts with excellent quality,the optimum process conditions should be set as heating temperature of 930℃,soaking time of 4min,stamping force of 7MPa,pressing speed of 75mm/s,quenching time of 15s,and water-flow rate of 1.1m/s.     

一种Si-Mn系超高强度钢板的热冲压成形试验研究

 采用弯曲件热冲压成形试验研究了板料加热温度、保温时间及移送时间等工艺参数对一种Si-Mn系超高强度钢板热成形零件的力学性能及微观组织的影响规律。结果表明,通过控制热成形工艺参数,在所设计的模具上可实现Si-Mn系超高强度钢板热成形零件的有效淬火,在合适的工艺参数下,可获得细小均匀的马氏体组织,从而获得抗拉强度1700MPa以上,伸长率10%以上的性能,达到原始板料抗拉强度的3倍左右,并明显高于传统的Mn-B系超高强度钢板。     

Fracture morphologies of a hot stamped steel and comparisons with several sheet metals

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.     

中锰钢温成形技术探讨

使用Gleeble-3800热模拟试验机研究了中锰钢(温成形钢)和22MnB5钢(热成形钢)的微观组织、力学性能和高温拉伸性能.结果表明:与22MnB5钢相比,在获得1 500 MPa级的抗拉强度时,中锰钢的加热温度可从950℃降低到800℃,钢的组织明显细化并且没有发生表面脱碳,断后伸长率从7.5％提高到10％.高温拉伸试验结果表明:中锰钢比22MnB5钢具有更高的延伸率和硬化指数,可以减小成形过程中局部减薄过高导致的样件破裂.     

Study on hydrogen induced delayed fracture of 1500 and 2000MPa hot stamping steels

The application of hot-stamping steel (HS) in the automobile is an inevitable trend, but the hydrogen embrittlement sensitivity of HS steel still needs to be studied and improved. The hydrogen diffusion behavior and hydrogen embrittlement sensitivity of 1500 and 2000MPa hot stamping steels were studied by means of hydrogen penetration, slow strain rate tensile (SSRT), and fracture analysis. The results show that the apparent diffusion coefficient Dap (1.71×10-7cm2/s) of 1500HS is significantly less than the Dap (3.45×10-7cm2/s) of 2000HS; delayed fracture resistance of 1500HS is superior to 2000HS. From the fracture analysis, under the same hydrogen charging conditions, the fracture morphology of 1500HS changed from typical dimple ductile fracture to quasi cleavage brittle fracture, while 2000HS changed from dimple morphology to intergranular brittle fracture with the increase of hydrogen charging current density. While the deformation degree of 2000HS was very small, the local hydrogen content and stress value had reached the critical deal. The hydrogen reduced the bonding force between grains, resulting in the nucleation and propagation of microcracks. Therefore, with the improvement of the strength of HS steel, Ti and V micro alloyed elements should be properly added to form nano precipitates, as irreversible hydrogen traps to capture hydrogen atoms, hinder their diffusion and segregation, and effectively refine the structure and pinning dislocations, to improve the resistance to hydrogen induced delayed fracture of HS steel.     

30SiMnCrB5热成形钢的微观组织和力学性能

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.      

热冲压钢镀层技术的研究现状

简要介绍了汽车用钢热冲压工艺技术的特点及其对镀层的性能要求,在此基础上着重描述了近年来国内外热冲压钢镀层技术的研究进展,详细列出了Al-10Si镀层的使用性能及GI(Galvanized)、GA (Galvanealed)镀层的研究状况.针对热冲压钢镀层产品的使用现状和未来需求方向,指出除了Al-10Si镀层外,发展GI/GA热冲压镀层技术是未来热冲钢发展的一个重要方向.     

材料参数对汽车部件冲压成形性的影响及参数控制

阐述了冷轧薄钢板性能对汽车部件冲压成形性的影响,采用模拟成形方法,对实物成形性进行了评价.分析了相关制造工艺对冷轧薄钢板性能的影响,指出不同的汽车部件应采取的性能参数.     

温成形中锰钢的组织性能评价

 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。     

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。