稀土对含镍低碳铸钢组织和性能的影响

Effect of Rare Earth on Microstructure and Properties of Low Carbon Cast Steel Containing Ni

以含镍低碳铸钢为研究对象,通过改变一号稀土加入量,经过金相组织观察、拉伸试验、冲击试验、夹杂物形貌分析、能谱分析等,研究RE含量变化对铸钢试样组织和性能的影响.研究结果表明：铸钢试样经调质处理后,组织为细小回火索氏体,存在少量铁素体.随着一号稀土质量分数增加,回火索氏体含量增多,晶粒尺寸减小;长条状或者尖角状夹杂物减少,稀土夹杂物主要是以球状或者近球状的形态存在,大小在5～10μm.抗拉强度、屈服强度和布氏硬度总体上呈现不断增加的趋势,在一号稀土含量为0.5%时,其值最高,抗拉强度为905.2 MPa,屈服强度为776.7 MPa,布氏硬度为274.冲击功先增加后降低,一号稀土质量分数在0.3%时,冲击功值为80 J.

The effect of RE content on microstructure and mechanical properties of low carbon cast steel containing Ni was studied by optical microscope observation,tensile testing,impact testing,inclusion morphology analysis and EDS.The experimental results show that there are many tempered sorbite and a little ferrite in quenching and tempering cast steel.The content of tempered sorbite increases and the size of tempered sorbite decreases with increasing of RE.Additive of RE improves the morphology of inclusion,the inclusion containing RE is sphere-like,and the size is 5 μm-10 μm.The strength and hardness increase with increasing of RE content,the maximum value of ultimate tensile strength,yield strength and hardness is 905.2 MPa,776.7 MPa and 274,respectively.The impact energy increases firstly and then decreases with increasing of RE content.The maximum value of impact energy is 80 J when the content of RE is 0.3%.