核黄素加速X80管线钢SRB腐蚀和低周疲劳失效研究

Study on riboflavin accelerated SRB corrosion and low cycle fatigue failure of X80 pipeline steel

埋地管道服役的土壤中多种微生物杂居,产电微生物分泌的电子穿梭体可能会影响微生物的腐蚀行为;且管道常出现低频压力波动、长期承受交变载荷作用,会使其产生低周疲劳。基于此,在研究硫酸盐还原菌对X80管线钢腐蚀的基础上,探究内源性电子穿梭体核黄素对微生物腐蚀疲劳的影响。结果表明:核黄素通过加速电子转移,促进了细菌腐蚀金属,但没有改变腐蚀产物及历程。在4组0.4%~0.7%应变幅下,2组预腐蚀体系相对未腐蚀体系疲劳寿命分别降低了17.5%~27.8%和33.5%~58.1%;随着应变幅增大,塑性应变幅在总应变幅中的占比也逐渐增大;腐蚀前后材料的循环响应特征和Masing特性没有改变;由应变、应变能密度和疲劳韧性寿命曲线预测结果可知:细菌腐蚀对钢材的塑性应变寿命影响显著,且疲劳断口分析验证了细菌腐蚀会加速钢材塑性失效。

A variety of microbial species coexist in the soil where buried pipelines are in service,and the electron shuttles secreted by electricity-generating microorganisms may affect the corrosion behavior of microorganisms.Moreover,pipelines often experience low-frequency pressure fluctuations and long-term exposure to alternating loads,which can lead to low-cycle fatigue.Based on this,the influence of endogenous electron shuttles riboflavin on microbial corrosion fatigue was explored by studying the corrosion of X80 pipeline steel by sulfate-reducing bacteria.The results show that riboflavin promotes bacterial corrosion of metals by accelerating electron transfer,but does not change the corrosion products or process.Under the strain amplitude of 0.4%to 0.7%,the fatigue life of the two pre-corrosion systems relative to the non-corrosion system decreased by 17.5%to 27.8%and 33.5%to 58.1%,respectively.As the strain amplitude increases,the proportion of plastic strain amplitude in the total strain amplitude gradually increases.The cyclic response and Masing characteristics of the materials before and after corrosion remain unchanged.The prediction results of strain,strain energy density,and fatigue toughness life curves indicate that bacterial corrosion has a significant impact on the plastic strain life of steel,and fatigue fracture analysis verifies that bacterial corrosion accelerates the plastic failure of steel.