摘要
利用热力学计算软件Thermo-Calc对Nb、Ti含量变化对其碳氮化物析出的影响规律进行计算,确定了1800 MPa热成形钢的成分。对该热成形钢的平衡相图、主要析出相的析出温度、特定相中元素含量随温度的变化、析出相的长大行为进行了计算,得到了该材料的主要相组成和相变特征基础数据。对微合金1800 MPa热成形钢的力学性能和三点弯曲性能进行了检测,结果表明其具有良好的强韧性。利用电子背散射衍射技术(EBSD)对热成形钢淬火后的组织进行了表征,结果表明细小的奥氏体晶粒和细小的马氏体块(Block)是1800 MPa热成形钢具有高强韧性的主要原因。最后采用充氢+慢拉伸的方法检测了热成形钢的延迟断裂敏感性,表明在充氢时间小于2 h的条件下,热成形钢具有优异的延迟断裂敏感性。
Thermodynamic calculation software Thermo-Calc was used to calculate the influence of the change of Nb and Ti content on the precipitation behavior of carbon nitride,the composition of 1800 MPa hot-formed steel was determined.The equilibrium phase diagram,the precipitation temperature of the main precipitated phase,the change of element content with temperature and the growth behavior of the precipitated phase were calculated,the basic data of the main phase composition and phase transformation characteristics were obtained.The mechanical properties and 3 point bending properties of microalloy 1800 MPa hot stamping steel have been tested.The test results show that the steel has good toughness.The microstructure of the hot formed steel after quenching was characterized by Electron Back Scattering Diffraction(EBSD).The characterized results show that the small austenitic grains and small martensitic blocks are the main causes for the high toughness of the 1800 MPa hot formed steel.Finally,the delayed fracture sensitivity of the hot-formed steel was measured by hydrogen filling and slow drawing method.The measured results show that the hot stamping steel has excellent delayed fracture sensitivity when the hydrogen filling time is less than 2 h.
作者
耿志宇
张宇
薛晗
王静静
周天鹏
刘旭明
Geng Zhiyu;Zhang Yu;Xue Han;Wang Jingjing;Zhou Tianpeng;Liu Xuming(Ansteel Beijing Research Institute Co.,Ltd.,Beijing 102211)
出处
《汽车工艺与材料》
2023年第9期42-50,共9页
Automobile Technology & Material
