热处理冷却方式对铁素体基体球墨铸铁组织与性能的影响

Effect of Heat Treatment Cooling on Microstructure and Property of Ductile Iron with Ferritic Matrix

将铁素体基体球墨铸铁加热到930℃保温2 h,分别采用炉冷、空冷、喷雾冷却和水冷,对试样进行组织分析和力学性能测试,研究冷却方式对球墨铸铁组织和性能的影响。结果表明,加热到930℃保温2 h,点状石墨略有减少,球状石墨尺寸有所增加且圆整度提高,并出现脱碳现象,个别球墨消失,留下黑色凹坑;冷却方式对石墨球无明显影响,而基体组织改变较为明显,炉冷时为铁素体基体,空冷和喷雾冷却时为铁素体和珠光体混合基体,而水冷时出现了马氏体。同时,随着冷却速度的提高,球墨铸铁的硬度呈现提高趋势。

The ductile iron with ferritic matrix was heated with 930℃ for 2 hrs, the microstructure and mechanical properties of samples with different cooling methods, such as furnace cooling, air cooling, spray cooling and water cooling, were analyzed and measured. The influence of cooling method on the microstructure and properties of nodular cast iron was studied. The results show that the spotted graphite will decrease slightly, the diameter of the spherical graphite increase and the roundness increase when it heats with 930℃ for 2 hrs. Some of the graphite disappeare, leaving black pits. The cooling modes have no obvious effect on the decarbonization of graphite ball, while the change of matrix is obvious. When it is cooling in the furnace, it is ferrite matrix; when it is in air cooling and spray cooling, it is ferrite mixed with pearlite matrix, while martensite appears when water cooling. At the same time, the hardness of nodular cast iron shows an upward trend as a whole with cooling rate increases.