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通过扫描和能谱分析及温度场模拟对350mm×470mm轴承钢连铸坯内部裂纹进行了研究。结果表明:裂纹处存在一定的夹杂物,夹杂物主要是Al2O3、MgO及部分铝硅酸盐,其中Al2O3夹杂物较大,长度达70μm,宽度为40μm左右;夹杂物主要是由于在炉外精炼中使用了高碱度和较高Al2O3含量的渣系,生产过程中卷渣等造成的;在连铸过程中,液固两相区存在夹杂物,成为裂纹源,铸坯固液界面所承受的应力及由此产生的塑性变形超过了所允许的高温强度和临界应变值,沿夹杂物方向扩展形成裂纹。
The internal crack of 350mm × 470mm bearing steel billet was studied by scanning and energy spectrum analysis and temperature field simulation. The results show that there are some inclusions in inclusions and the inclusions are mainly Al2O3, MgO and some aluminosilicates. The Al2O3 inclusions are larger, the length is up to 70μm and the width is about 40μm. The inclusions are mainly due to refining outside the furnace In the continuous casting process, inclusions exist in the liquid-solid two-phase zone and become the source of cracks. The slab solid-liquid interface is exposed Of the stress and the resulting plastic deformation exceeds the allowable high temperature strength and critical strain values, extending along the direction of inclusions to form cracks.