摘要
Automobile crankshaft steel 42CrMo, which requires excellent machinability and mechanical properties, cannot be manufactured by traditional methods. To achieve these qualities, the formation behavior of boron nitride （BN） inclusions in 42CrMo steel was studied in this article. First, the precipitation temperature and the amount of BN type inclusions with differ- ent contents of boron and nitrogen in molten steel were calculated thermodynamically by FactSage software. Then the mor- phology and the size of BN type inclusions as well as the influence of cooling methods on them were investigated by scanning electron microscopy. Furthermore, the effects of cooling rate and the contents of B and N in molten steel on the morphology, size, and distribution of BN type inclusions were studied quantitatively and detalledly by directional solidification experiments. It is found that different BN inclusions in molten steel can form by controlling the cooling rate and the contents of B and N, which is important for obtaining the excellent machinability of 42CrMo steel.
Automobile crankshaft steel 42CrMo, which requires excellent machinability and mechanical properties, cannot be manufactured by traditional methods. To achieve these qualities, the formation behavior of boron nitride （BN） inclusions in 42CrMo steel was studied in this article. First, the precipitation temperature and the amount of BN type inclusions with differ- ent contents of boron and nitrogen in molten steel were calculated thermodynamically by FactSage software. Then the mor- phology and the size of BN type inclusions as well as the influence of cooling methods on them were investigated by scanning electron microscopy. Furthermore, the effects of cooling rate and the contents of B and N in molten steel on the morphology, size, and distribution of BN type inclusions were studied quantitatively and detalledly by directional solidification experiments. It is found that different BN inclusions in molten steel can form by controlling the cooling rate and the contents of B and N, which is important for obtaining the excellent machinability of 42CrMo steel.
基金
supports by the National Natural Science Foundation of China (No.51274029)
the China Postdoctoral Science Foundation (No. 2012M510319)
