两种热冲压模具用钢的抗拉毛性能  

Anti-galling Performance of Two Hot Stamping Mould Steels

作　　者：孙强 黄苏起 蔡著文 党卫东[1,2] 吴晓春 SUN Qiang;HUANG Suqi;CAI Zhuwen;DANG Weidong;WU Xiaochun(School of Materials Science and Engineering,Shanghai University,Shanghai 200444,China;State Key Laboratory of Advanced Special Steel,Shanghai 200444,China)

机构地区：[1]上海大学材料科学与工程学院,上海200444 [2]省部共建高品质特殊钢冶金与制备国家重点实验室,上海200444

出　　处：《材料导报》2021年第10期10152-10157,共6页Materials Reports

基　　金：国家重点研发计划(2016YFB0300400,2016YFB0300402)。

摘　　要：诸多汽车零部件制造商通过表面处理缓解零部件的热冲压拉毛问题,但该处理将提高生产成本。为此,本研究从模具材料合金化配比出发,通过实验和理论研究,初步判断热冲压模具抗拉毛性能与模具材料抵抗塑性变形的能力有关,为验证该猜想,采用透射电子显微镜(TEM)、X射线衍射仪、应力仪、显微维氏硬度计等手段分析了两种模具材料(SDCM钢和SDHS2钢)回火态的碳化物类型、碳化物分布、位错密度、喷丸后的截面残余应力梯度和显微硬度梯度。结果表明:与SDHS2钢相比,抗拉毛性能较优的SDCM钢的屈服强度较高,其在相同的外加应力下,具备更强的塑性变形抗力,变形软化层较浅。此外,热处理后SDCM钢和SDHS2钢中均以钒系碳化物为主,其中高碳高钒低铬的SDCM钢中碳化物的体积分数和位错密度较大,使其具有较高的析出强化和位错强化效果,提高了材料的屈服强度。Hot stamping is a metal-forming process for stamping and forming high-strength steel plates,which can not only greatly improve the forming performance of the material,but also refine the grain size through high-temperature phase transformation.However,during the hot stamping process,the high-strength steel sheet has been heated above the austenitizing temperature.At this time,the yield strength of the high-strength steel sheet is low,and the high-strength steel sheet can easily be scratched by the debris knob.The mechanical properties of high strength steel plates were reduced significantly.In this respect,many auto parts manufacturers have relieved the hot-stamping galling problem of parts by surface treatment,but this treatment will increase production costs.For this reason,this study starts from the alloying ratio of the mould materials,and through experimental and theoretical research,it is preliminarily judged that the anti-galling performance of hot stamping moulds is related to the ability of plastic deformation resistance of the mould materials.In order to verify the conjecture,the transmission electron microscope(TEM),X-ray diffractometer,residual stress meter,micro Vickers hardness tester were used to observe the carbide types,carbide distribution,dislocation density in the two tempered materials(SDCM steel and SDHS2 steel),and residual stress gradient and micro Vickers hardness gra-dient of the section after shot peening.The results show that compared with SDHS2 steel,the yield strength of SDCM steel with better anti-galling performance is higher,which makes it have stronger resistance to plastic deformation under the same applied stress,making its deformation softening layer shallower.In addition,vanadium-based carbides are predominant in both SDCM steel and SDHS2 steel after heat treatment.Among them,SDCM steel with higher carbon content,higher vanadium content and lower chromium content contains higher carbide volume fraction and dislocation density,which results in higher precipitation strengthenin

关 键 词：热冲压模具钢 拉毛 塑性变形抗力 位错密度 碳化物 

分 类 号：TG76[金属学及工艺—刀具与模具] TG704