SWRCH8A冷镦钢变形组织与腐蚀性能研究

Deformation microstructure and corrosion properties of SWRCH8A cold heading steel

对SWRCH8A冷镦钢在室温经1/3和1/4冷镦变形后的组织与腐蚀性能进行研究。采用金相显微镜观察冷镦前后的微观组织,并用开路电位监测、Tafel曲线、电化学阻抗谱方法研究冷镦前后在质量分数为3.5%的NaC l溶液中的腐蚀行为。结果表明,冷镦前组织为铁素体和珠光体,珠光体在铁素体晶界处均匀分布,铁素体晶粒为等轴晶,大小约为10-20μm;冷镦后组织仍由铁素体和珠光体组成,但铁素体晶粒呈拉长的纤维状,晶粒尺寸变小,且随着冷镦变形量的增加,铁素体的变形程度增加;冷镦变形后样品的开路电位发生负移,随着冷镦变形量的增大,试样的自腐蚀电位负移,腐蚀速率加快;不同变形量SWRCH8A的电化学阻抗谱均由高频容抗弧和低频感抗弧组成。

The deformed microstructure and corrosion properties research of cold heading steel SWRCH8A was investigated by 1/3 and 1/4 cold heading test under room temperature.To observe the microstructure before and after cold heading by metalloscope,the electrochemistry corrision properties before and after cold heading in 3.5% NaCl solution was examined by open circuit potential test,Tafel curve and electrochemistry impedance spectrum.The results show that the microstructure of SWRCH8A before cold heading consists of ferrite and pearlite,while the pearlite is evenly distributed at the grain boundaries of ferrite and the ferrite equiaxed grain size is about 10~20μm.After cold heading,the microstructure are also ferrite and pearlite,but the ferrite is elongated fiber with a smaller size,and the deformation extent of ferrite increased with the cold heading deformation.With the increased cold deformation,the OCP values and the corrosion potential of the sample after cold heading is more negative,the corrosion rate is also accelerated.The electrochemical impedance spectrum is made up of high frquency capacity reactance arc and low frequency inductive reactance arc.