σ相对S32205双相不锈钢力学性能和耐蚀性的影响

Effect ofσphase on mechanical properties and corrosion resistance of S32205 duplex stainless steel

通过JMatPro软件模拟计算和试验结合的方式研究了S32205双相不锈钢中σ相的析出行为及对其力学性能和耐蚀性的影响。结果表明:通过JMatPro软件模拟计算得到的S32205双相不锈钢σ相析出鼻尖温度为875℃。当S32205双相不锈钢在875℃保温0~90 min,σ相含量快速增加,当保温时间增加至90~120 min时,σ相含量缓慢上升,而当保温时间为120~240 min时σ相含量达到饱和,最大为6.1%,与模拟计算结果基本符合。随着保温时间逐渐增加,S32205双相不锈钢的屈服强度、抗拉强度及显微硬度先快速增加后逐渐保持稳定,而伸长率呈下降趋势,强度和硬度与σ相体积含量成正比关系,σ相强化机理由Orowan强化机制转变为σ相的高弹性应变能强化机制。不同σ含量的S32205双相不锈钢的电化学试验结果表明随着σ相的含量逐渐增多,基体越容易贫Cr, S32205双相不锈钢越容易产生腐蚀,耐蚀性逐渐降低。

The precipitation behavior ofσphase in S32205 duplex stainless steel and its effect on mechanical properties and corrosion resistance of the steel were studied through a combination of JMatPro software simulation calculation and experiments.The results show that the precipitation nose temperature of theσphase in the S32205 duplex stainless steel obtained through JMatPro software simulation calculation is 875℃.When S32205 duplex stainless steel is held at 875℃for 0-90 min,theσphase content increases rapidly.When the holding time increases to 90-120 min,theσphase content slowly increases.When the holding time is 120-240 min,theσphase content reaches saturation,with a maximum of 6.1%,which is basically consistent with the simulation calculation results.As the holding time gradually increases,the yield strength,tensile strength and microhardness of the S32205 duplex stainless steel first rapidly increase and then gradually maintain stability,while the elongation shows a decreasing trend.The strength and hardness are proportional to the volume content of theσphase.The strengthening mechanism of theσphase is transformed from the Orowan strengthening mechanism to the high elastic strain energy strengthening mechanism of theσphase.The electrochemical test results of the S32205 duplex stainless steel with differentσphase contents show that as the content of theσphase gradually increases,the matrix is more prone to Cr-depleted,and the S32205 duplex stainless steel is more prone to corrosion,resulting in a gradual decrease in corrosion resistance.