电渣熔铸-熔焊法生产大直径内燃机曲轴的工艺研究

Big-diameter Crankshafts Produced by Electroslag Casting and Welding

介绍了采用电渣熔铸-熔焊法生产大直径内燃机曲轴毛坯的基本原理及熔铸、熔焊工艺。测定了铸件的化学成分分布,并对非金属夹杂和低倍组织进行了研究。结果表明:熔铸、熔焊工艺的要点是采用冷却能力较强的紫铜做结晶器工作面,冷却水层厚度为10mm,局部冷却速度≥2300℃/min,结晶器出水温度≤45℃;采用熔点低、流动性好的三元渣系(主要成分为CaF2+Al2O3+CaO)并对其进行熔化预处理。与锻件相比,整个电渣熔铸件(包括熔焊区)金属纯净,组织致密,成分均匀,硫、磷等有害元素含量低,夹杂物含量大幅度降低,疏松与偏析大为减少。

Based on the theory of electroslag casting and the technologies of electroslag casting-welding, the production of big-diameter crankshafts is studied. The contents of C, Si, Mn, P,S and Mo in electroslag casting-welding and forging crankshaft are measured. The amount of different inclusions is analyzed. The results show that purple copper is used as mould face to enhance cooling effect. The cooling water layer thickness is 10 mm,Sub-cooling rate is more than 2 300℃/min and temperature is less than 45℃. Three- element slags（CaF2＋Al2O3＋CaO） with low melting point and good mobility are used and need to be melted as pretreatment. Compared with forging crankshafts, the composition of electroslag casting-weldings is rather uniform at different positions in casting, and S, P contents are rather low, the total amount of inclusions is lowered.