炼钢脱氧制度对碳锰钢坑孔腐蚀扩展的影响

选用脱氧制度不同的碳锰钢,通过冶金分析考察了试验用钢的冶金特点、夹杂物及组织特征,分析了冶金工艺对组织及夹杂物类型的影响。通过挂片试验比较了不同脱氧制度钢的坑孔腐蚀速度,并结合闭塞腐蚀电池及特殊的金相分析方法,研究了脱氧制度对蚀坑扩展的影响及影响机理。结果表明,炼钢脱氧制度对锰铌钢的组织与夹杂物有重要影响,沸腾钢脱氧差,硫化物夹杂为土豆状Ⅰ类硫化物;镇静钢脱氧程度高,其硫化物夹杂为共晶态Ⅱ类硫化物,轧制后为条片状;半镇静钢的脱氧情况介于前二者之间,硫化物夹杂轧制后为短条状或长雪茄状。随着钢的脱氧程度下降,在同样外阴极极化条件下,其闭塞腐蚀电流减小。挂片结果表明,脱氧程度较差的半镇静锰铌钢的耐蚀性明显优于镇静锰铌钢,它们之间的局部腐蚀程度差异基本与室内闭塞腐蚀电池测试结果相同。

Effect of Deoxygen on Pitting Propogation of Carbon and Manganese Steels

For five kinds of deoxygenized carbon manganese steels,the microstructure and inclusions was studied with metallurgy analysis,the corrosion rate of pitting was detected with immersion tests,and the mechanism of pitting was investigated with OCC testing and microstructure analysis.The results show that deoxygen methods had much important effect on the microstructure and inclusions of the manganese steels.The deoxygen of boiling steels is poor and the inclusions is I type potato like sulfide.The deoxygen of killed steel is well and the inclusions were eutectic Ⅱ type sulfide which was bar-slice like after rolling.The inclusions of half-killed steel are short bar like or long cigar like.With the decline of deoxygenization degree,the OCC current density dropped.The immersion test results show that the corrosion resistance of half-killed steels is better than that of the killed manganese steels.The corrosion rate of pitting in immersion test is the same with OCC test in the laborotary.