用长效孕育剂改善球墨铸铁的力学性能

介绍了差速器壳体的铸件结构及技术要求,详细阐述了解决珠光体-铁素体混合基体球铁综合性能不达标问题的措施。采用湿型粘土砂造型,化学成分设计为:w(C)3.5%~3.9%,w(Si)2.2%~2.8%,w(Mn)≤0.4%,w(P)≤0.07%,w(S)≤0.025%,w(RE)0.02%~0.04%,w(Mg)0.03%~0.06%;利用3 t中频感应电炉熔炼,采用喂丝球化处理方法,球化剂加入量为1%,球化处理温度为1 500℃。原工艺采用促进珠光体型孕育剂,结果力学性能达不到技术要求,后来在其它工艺条件不变的情况下,通过采用含有Ba、Sr、RE的长效孕育剂,使铸件金相组织和力学性能均符合技术要求。

Using Long Effective Inoculant to Improve Mechanical Properties of Nodular Cast Iron

The casting configuration of differential housing and its technical requirements were introduced. The measures to solve the problem that the comprehensive properties of the nodular cast iron with pearlite-ferrite mixing matrix hadn＇t reached the standard were described in detail. The green clay sand was used for molding;the casting chemical composition was designed as follows：w（C） 3.5%-3.9%,w（Si） 2.2%-2.8%,w（Mn） ≤0.4%,w（P） ≤0.07%,w（S） ≤0.025%,w（RE） 0.02%--0.04%,w（Mg） 0.03% -4）.06% ;3 t medium frequency induction furnace was used for melting,cored-wire injection process was used for nularizing treatment,the nodularizing alloy addition was of 1%;the nodularizing treating temperature was of 1 500 ℃. Formerly the pearlite promoting type inoculant was used and,as the result,the mechanical properties did not reach the technical requirements.Then, under the other process conditions being unchanged,the Ba,Sr,RE-containing long effective inoeulant was used and as the result,both the microstrncture and mechanical properties have met the technical requirements.