大连饱和水土壤中Q235B钢和L245钢的腐蚀行为

Corrosion Behavior of Q235B Steel and L245 Steel in Dalian Soil Saturated with Water

对管线钢L245土壤腐蚀的研究目前未见报道。采用失重和电化学阻抗谱测试方法,研究了大连市2种在役燃气管线钢Q235B和L245在饱和水土壤中的腐蚀特性,比较了两者的腐蚀行为。结果表明:Q235B钢的腐蚀电位比L245钢高20mV左右;腐蚀初期两者的阻抗谱均由高频小容抗、中频大容抗和低频小感抗组成,腐蚀后期低频小感抗退化直至消失;随着时间的推移,Q235B钢的腐蚀速率先增大后缓慢减小,L245钢的腐蚀速率先缓慢减小后急剧减小;同等条件下L245钢的耐蚀性要优于Q235B钢。

The corrosion behavior of two kinds of gas pipeline steels Q235B and L245 in water saturated soil of Dalian city was evaluated and compared by means of weight loss test and electrochemical impedance spectroscopy. Results show that the corrosion potential of Q235B steel is higher than that of L245 steel by 20 mV. In the initial stage of corrosion,the electrochemical impedance spectra of both steels consisted of three components including high frequency small capacitive reactance,intermediate frequency large capacitive reactance and low frequency small inductive reactance. In the later stage of corrosion,the low frequency small inductive reactance was degraded until it disappeared. With progress of time,the corrosion rate of Q235B steel increased initially and then decreased,while that of L245 steel decreased continuously. L245 steel had better corrosion resistance than Q235B steel.