奥氏体化工艺对22MnB5热成形钢锌基镀层结构及裂纹的影响  

Effect of austenitizing process on structure and cracks of galvanized layer on 22MnB5 hot stamped steel

作　　者：赵景轩 梁健 张玲玲 董伊康 王立辉 苗斌 沈春光 郑士建 Zhao Jingxuan;Liang Jian;Zhang Lingling;Dong Yikang;Wang Lihui;Miao Bin;Shen Chunguang;Zheng Shijian(School of Materials Science and Engineering,Hebei University of Technology,Tianjin 300401,China;HBIS Material Technology Research Institute,HBIS Group,Shijiazhuang Hebei 050023,China)

机构地区：[1]河北工业大学材料科学与工程学院,天津300401 [2]河钢材料技术研究院,河北石家庄050023

出　　处：《金属热处理》2024年第11期296-301,共6页Heat Treatment of Metals

基　　金：校企合作项目(HG2021123,HG2021104-JS-2022-16)。

摘　　要：以22MnB5热镀锌热成形钢为研究对象,将其加热至不同奥氏体化温度,保温不同时间后热冲压成形,并用扫描电镜(SEM)及能谱仪(EDS)、X射线衍射(XRD)分析等手段对镀锌层的组织结构、表面氧化物及开裂情况进行表征,探究奥氏体化工艺对热成形钢锌基镀层结构及裂纹的影响规律。结果表明,奥氏体化后镀层主要由α-Fe(Zn)相和少量脆性Fe_(3)Zn_(10)相组成,加热温度由870℃升高至890℃热成形时,镀层厚度达到最大且其中Fe_(3)Zn_(10)相含量降低,使得热成形后镀层中裂纹明显减少;当加热温度升高到910℃热成形时,由于Zn元素挥发,镀层厚度略有降低,表面形成大量Mn、Zn等元素氧化物,镀层中Fe_(3)Zn_(10)相含量显著增加,导致热成形后形成大量裂纹。当保温时间由370 s延长至400 s(加热温度为890℃)时,促进了Fe-Zn反应,形成更多数量的α-Fe(Zn)相,致使镀层厚度增加,但表面氧化程度并无显著变化。22MnB5 hot-dip galvanized hot stamped steel was heated to different austenitizing temperatures for different time for hot stamping.The effect of austenitizing process for hot stamping on the microstructure and cracks of the galvanized layer on hot stamped steel was investigated through characterization of the microstructure,surface oxides and cracking of the galvanized layer by scanning electron microscope(SEM),energy dispersive spectrometer(EDS)and X-ray diffraction(XRD)analysis.The results indicate that the galvanized layer is primarily composed ofα-Fe(Zn)and a small amount of brittle Fe_(3)Zn_(10)after austenitizing.With an increase in heating temperature from 870℃to 890℃,the galvanized layer thickness reaches the maximum,and there is a noticeable decrease in the presence of Fe_(3)Zn_(10),leading to a reduction of cracks after hot stamping.However,the galvanized layer thickness slightly decreases at 910℃due to Zn volatilization,resulting in the formation of a large amount of Mn,Zn and other elemental oxides on the surface,and the content of Fe_(3)Zn_(10)in the galvanized layer significantly increases,leading to a large number of cracks after hot stamping.When the holding time at 890℃is extended from 370 s to 400 s,the Fe-Zn reaction is promoted,moreα-Fe(Zn)phases are formed,resulting in an increase of the galvanized layer thickness,but with no significant change of the surface oxidation degree.

关 键 词：22MnB5热成形钢 锌基镀层 奥氏体化 组织结构 裂纹 

分 类 号：TG156.1[金属学及工艺—热处理]