电冶钢结硬质合金DGJW50热冲击行为的研究

Research on the Thermal Shock Behaviors of Electro-slag Melting and Casting Steel-bonded Carbide DGJW50

对DGJW50电冶钢结硬质合金进行了热冲击试验，在光学金相显微镜下观察了裂纹的形成和组织变化。实验结果表明，热冲击裂纹的形成存在孕育期。随着热冲击循环温度的升高和冷却速率的加快，热冲击裂纹孕育期缩短，裂纹扩展速率加快。裂纹孕育期间，缺口处形成蚀坑。且蚀坑是沿着碳化物／钢基体界面处分布的，随着热冲击循环次数的增加，蚀坑长大并连接成裂纹。裂纹形成以后。沿着碳化物／钢基体界面扩展。

Thermal shock test of DGJW50 steel bonded carbide was performed, the formation of crack and change of structure was investigated by optical microscope. The results show that there is a incubation period in the formation of crack, when the cycle temperature of thermal shock is increased and the cooling speed is fastened, the incubation period of thermal shock crack is shortened, the propagation speed is fastened. In the incubation period, corrosive holes are formed in the notch, and they are distributed at the interfaces of WC/steel phases, with the increasing of thermal shock cycles, corrosive holes develop into cracks. After cracks are formed, Cracks propagate along the interfaces of WC/steel phases.