自耗电极电渣熔铸分步成型曲轴毛坯工艺

Cranksshafts Manufactured by Electroslag Multistep Smelting-casting with Consumable-electrodes

采用分步(部分 整体)成型工艺,电渣熔铸出大直径内燃机曲轴毛坯,并测定了铸件的化学成分及非金属夹杂和低倍组织。电渣熔铸的工艺要点是采用熔点低、流动性好的四元渣系[质量分数为( 2 0 %～3 0 % )的CaF2 、( 2 0 %～3 0 % )的Al2 O3 、( 1 5 %～2 0 % )的CaO、( 1 5 %～2 0 % )的MgO] ,并对其进行预熔处理除氢,通过提高渣的纯度来防止熔接区夹渣;采用冷却能力较强的紫铜做结晶器工作面,冷却水压>0 .5MPa ,流速>4m/s ,结晶器出水温度<5 0℃,为防止裂纹,结晶器采用柔性连接技术。结果表明:电渣熔铸件成分均匀,组织致密,疏松与偏析大为减少,硫含量降低6 0 % ,磷含量降低2 0 % ;铸后采用80 0℃退火,可得到良好的强韧性配合。

The chemical compossition and macrostructure of the cranksshaft for internal combustion engine with big diameter manufactured by electroslag multistep smelting-casting were investigated.Quaternary slag system,including CaF_2(20%～30%),Al_2O_3(20%～30%),CaO(15%～20%),MgO(15%～20%),with low melting point and good fluidity was used,in which the hydrogen-removal was pretreated to prevent slag inclusion in welding-zone through improving the purity of slag system.The red copper was used for mould face.Cooling water pressure is more than 0.5 MPa,and flow velocity is more than 4 m/s,and the effluent temperature is less than 50 ℃.Flexible connection was applied for the mould to prevent the crack.The results showed that the crankshaft possesses uniformly composition and soundness microstructure,in which shrinkage porosity and segregation was remarkably decreased,and S content is decreasd by 60% and P content is decreased by 20%.The crankshaft with high toughness and strength can be obtained after annealingat 800 ℃.