45钢电镀锌-镍合金过程中的渗氢行为及其氢脆敏感性

Hydrogen Permeation Behavior of 45 Steel during Zinc Nickel Alloy Electroplating and Hydrogen Embrittlement Susceptibility of the Electroplated Coating

目前,有关锌-镍合金电镀过程中氢脆问题的研究较少。采用双电解池测氢法研究了45钢在不同温度、电流密度、pH值下电镀锌-镍合金过程中的渗氢变化规律。通过慢应变速率拉伸试验法评价镀层氢脆性能,并用扫描电子显微镜(SEM)观察断口的微观形貌。结果表明:镀液温度对渗氢电流的影响最大,镀液温度越高,镀样断裂时间越短,氢脆敏感性越强;镀样的断裂时间小于空白样,说明镀样有不同程度的氢脆敏感性;镀样的断口呈解理断裂特征,空白样呈韧性断裂特征;用渗氢电流曲线可间接评价镀样的氢脆敏感性。

Double-electrolysis-cell hydrogen-monitoring method was adopted to investigate the hydrogen permeation behavior of 45 steel during Zn-Ni alloy electroplating under different temperature,current density and bath pH value.In the meantime,tensile tests at a slow-strain-rate were conducted to evaluate the hydrogen embrittlement susceptibility of the electroplated coating.Furthermore,the morphology of the fractured surface of the electroplated coating was examined with a scanning electron microscope.Results indicated that the electroplating bath temperature had the most significant effect on the hydrogen permeation current.The fractured time of as-plated steel tended to decrease with elevating bath temperature,and the hydrogen embrittlement susceptibility of the electroplated coating tended to rise therewith.Besides,as-plated steel sample had shorter fractured time than the blank sample,which indicated that the former had higher hydrogen embrittlement susceptibility.Moreover,as-plated steel sample was dominated by cleavage fracture,while the blank counterpart was dominated by tough fracture.In one word,the hydrogen embrittlement susceptibility of electroplated Zn-Ni alloy coating could be indirectly evaluated by using hydrogen permeation current curve.