低合金白口铸铁二次渗碳体的网状析出现象

Formation of the Secondary Cementite Network in Low Alloy White Cast Iron

研究了低合金白口铸铁经高温保温处理后空冷时二次渗碳体呈网状析出的现象,比较了过共析钢与低合金白口铸铁先共析渗碳体的异同.实验表明,空冷条件下热处理保温温度同样是决定低合金白口铸铁中二次渗碳体是否呈网状析出的主要因素.保温温度低于Acm有利于避免或减弱网状析出现象.该Acm温度要由低合金白口铸铁铸态显微组织中基体部分的平均含碳量确定.给出了根据铸态共晶碳化物的体积分数来计算基体平均含碳量的公式.

The formation of the secondary cementite network during the air cooling of the low alloy white cast iron after high temperature holding is investigated.The similarities and the differences of the preeutectoid cementite in hypereutectoid steel and in low alloy white cast iron are compared.The experimental results demonstrate that the holding temperature acts as an important factor affecting the formation of the secondary cementite network during the air cooling of the low alloy white cast iron.Holding temperatures below Acm are favorable for avoiding the secondary cementite network.The value of Acm should be determined by the mean carbon content of the matrix in the as-cast microstructure of the alloy,and a formula is presented for calculating the mean carbon content of the matrix according to the volume fraction of the as-cast eutectic carbide.