厚大高锰钢铸件微裂纹形成机理研究

Mechanism of the Micro-Cracks Generation in Heavy High Manganese Steel Casting

以高锰钢组合辙叉心轨铸件为研究对象,分析了厚大(厚度大于120mm)高锰钢铸件微观裂纹形成机理。通过金相显微镜和扫描电镜(SEM)观察,发现微观裂纹沿晶界分布,并且在裂纹周围富集大量的氧化物、碳化物和低熔点磷共晶。铸件凝固过程中的拉应力使得微观裂纹在这些氧化物、碳化物和低熔点磷共晶处萌生。因此,凝固过程中的拉应力及这些夹杂物的存在是厚大高锰钢铸件形成微观裂纹的主要原因。

The mechanism of the micro-crack produced in heavy high manganese steel castings （〉120 mm） was studied in this paper. Results show that the micro-cracks distribute along the grain boundaries, and a great deal of oxides, carbides and low-melting point phosphide eutectics are found to enrich around the micro-cracks by metallographic microscope and the scanning electronic microscope （SEM） .The tensile stress formed during solidification causes the microscopic crack to initial in these oxides, the carbide and carbides and low-melting point phosphide eutectics place. Therefore, the existences of the tensile stress and these inclusions during solidification are the main factors of microscopic crack generation in the heavy high manganese steel casting.