热冲压工艺参数对30MnB5和22MnB5钢板成形淬火后力学性能和微观组织的影响

摘要

The influences of hot stamping parameters such as heating temperature,soaking time,deformation temperature and cooling medium on the phase transformation,microstructure and mechanical properties of 30MnB5 and 22MnB5 are investigated and analyzed in this work.The quenching experiment,tensile testing,hardness measurement and microstructure observation were conducted to obtain the mechanical and microstructural data.The results indicate that 30MnB5 possesses a higher tensile strength but a lower elongation than 22MnB5,if hot stamped at the same process parameter.The tensile strength and hardness of the hot stamped specimens decrease under inappropriate heating conditions for two reasons,insufficient austenitization or coarse austenite grains.The austenitic forming rate of 30MnB5 is higher than that of 22MnB5,because more cementite leads to higher nucleation rate and diffusion coefficient of carbon atom.More amount of fine martensite forms under the higher deformation temperature or the quicker cooling rate.%本文旨在研究加热温度、保温时间、变形温度和冷却介质等热冲压工艺参数对30MnB5和22MnB5高强钢板相变、微观组织和力学性能的影响规律.使用平板模具模拟了硼钢热冲压冷模具淬火过程,并对淬火后的零件试样进行了拉伸测试、硬度测量和微观组织观测.研究结果表明,在相同的热冲压工艺参数下,淬火后的30MnB5比22MnB5具有更高的抗拉强度、更低的伸长率;不合适的加热参数由于不充分奥氏体化或奥氏体晶粒粗大等原因导致淬后零件抗拉强度和硬度的降低;30MnB5的奥氏体化速率高于22MnB5的奥氏体化速率,这是由于更多的渗碳体导致了更高的形核率和碳原子扩散率;较高的成形温度和较快的冷却速率易于在淬后零件中形成细小的马氏体组织.