H13钢喷射成形热锻模坯组织分析

Analysis on microstructure of hot forging billet H13 in the spray forming

对喷射成形H13热锻模沉积坯进行了金相分析、SEM组织形貌观察和能谱分析、硬度宏观分布测试。结果表明:喷射沉积H13钢的凝固晶粒为细小等轴晶,晶粒大小分布不均匀;喷射态的微观组织主要由贝氏体、马氏体、残留奥氏体组成,并有少量碳化物及夹杂物;喷射沉积坯的宏观组织存在明显层状特征,层与层之间存在不同程度的孔隙,沉积坯的底部及顶部区域的孔隙率高;孔隙率高、组织不均匀是沉积坯硬度分布不均的原因;造成沉积坯组织不均匀的原因是金属液流温度和速度在整个喷射过程不均匀。

Metallographic, SEM and EDS analysis and HRC hardness test were implemented on deposition billet of hot forging die H13 in the spay forming. The results show that the solidification grain in the spay-formed H13 is fine equiaxed crystal with nonuniform distribu- tion. The spray-formed microstructures are composed of bainite, martensite, retained austenite, and a small amount of carbide and impu- rites. The macrostructure of the spay-formed deposition billet is of lamellar characteristic distinctly. The porosity is different between lay- ers, and higher porosity is found at both the bottom and the top of deposition billet. The reasons of nonuniform distribution of deposition billet hardness are high porosity and nonuniform microstructure. The nonuniform microstructure of deposition billet should attribute to the uneven of temperature and the speed of the metal stream during the whole spray process.