82B高碳钢热轧盘条心部异常组织分析及改善措施

Abnormal Core Microstructure Analysis and Improvement Measures of 82B High Carbon Steel Hot Rolled Wire Rods

某钢厂82B高碳钢热轧盘条心部出现网状渗碳体和马氏体异常组织。通过化学成分分析、金相检验、扫描电镜分析等方法,分析了其心部异常组织产生的原因。结果表明:82B高碳钢热轧盘条心部出现马氏体是由于坯料心部存在晶内锰、铬合金元素微观正偏析,并在轧制后的马氏体形成温度段的冷却速度偏快;心部出现网状渗碳体是由于坯料心部存在较严重的碳元素宏观正偏析,并在轧制后的索氏体形成温度段的冷却速度偏慢。通过多次工艺试验,调整盘条轧制工艺和轧后冷却工艺,不仅消除了心部马氏体组织,而且降低了网状渗碳体出现的概率。

Networked cementite and martensite abnormal microstructure appeared in the core of 82 Bhigh carbon steel hot rolled wire rods of a steel plant.The formation causes of the abnormal core microstructure were analyzed by chemical composition analysis,metallographic examination,scanning electron microscopy analysis and other methods.The results show that the martensite in the core of 82 Bhigh carbon steel hot rolled wire rods is due to the intragranular micro-positive segregation of manganese and chromium alloy elements in the core of the billet,and the fast cooling rate of martensite formation period after rolling.The occurrence of core networked cementite is due to the presence of severe macro-positive segregation of element carbon in the core of the billet,and the slow cooling rate of sorbate formation period after rolling.After several process trials and improvements of rolling process and cooling process after rolling,the core martensite was eliminated and the probability of existence of networked cementite was also reduced.