过热度对轴承钢内部组织的影响

Influence of superheat on internal structure of the bearing steel

利用枝晶腐蚀低倍检验技术、铸坯及盘条淬火+回火热处理金相检验等技术研究了过热度对轴承钢内部组织的影响.结果表明低过热度工艺铸坯等轴晶比例提高,二次枝晶间距变小,铸坯内部偏析、缩孔等冶金缺陷有所改善,但盘条酸洗低倍组织及碳化物不均匀性差别不大.两种工艺铸坯混晶区均比中心等轴晶区偏析严重,存在大量的大尺寸共晶碳化物.

The influence of superheat on internal structure of the bearing steel is researched by the macrostructure inspection tech-nology of dendrite corrosion and metallographic test method of bloom and wire with quenching and tempering heat treatment. The re-sults show that the equiaxed crystal ratio of the low superheat process increase. The secondary dendrite spacing decreases. Internal metallurgical defects such as segregation, shrinkage cavity improve. But there is little difference in the wire rod pickling macrostructure and carbide nonhomogeneity. Segregation control in the mixed crystal area is more serious than that in equiaxed crystal area. And there are a large numble of large size eutectic carbides.