含银H70铸态黄铜合金组织及性能研究
Structure and properties of H70 silver-containing cast brass alloy
-
摘要: 添加不同含量银元素制备含银H70铸态黄铜合金, 通过光学显微镜、硬度测试、线性极化曲线和交流阻抗谱等方法分析铸态试样的组织和性能.研究结果表明, 试样的低倍组织由柱状晶区和等轴晶区两部分组成, 银元素的添加能显著细化晶粒尺寸, 银含量为0.1 %时晶粒尺寸最小; 随着银含量的增加, 金相组织中析出相逐渐减少, 枝晶偏析程度增加; 硬度值先升高后降低, 银含量为0.1 %时取得最大值, 为80.8 HV; 人工汗液电化学试验表明, 银含量为0.5 %时自腐蚀电流密度最低, 点蚀倾向性最小, H70的Rp值最大, 耐腐蚀性能最好.Abstract: The as-cast silver-containing H70 brass were prepared by adding different contents of silver. The structure and properties of the casting materials were analyzed by means of optical microscope, hardness test, linear polarization curve and electrochemical impedance. The results show that the low magnification of the samples are composed with columnar crystal and equiaxed crystal regions. The addition of silver element can significantly refine the grain size, and the grain size is the smallest when the silver content is 0.1%. With the increase of silver content, the precipitation phases gradually decrease and the degree of dendrite segregation increases in the metallographic structure. The hardness value increases first and then decreases, reaching the maximum value of 80.8 HV when the silver content is 0.1%. The electrochemical test of artificial sweat shows that the self-corrosion current density is the lowest and the pitting tendency is the smallest when the silver content is 0.5%. The Rp value of H70 is the largest and its corrosion resistance is the best.