热成形SAF2507双相不锈钢析出相与耐腐蚀性能

Precipitated phases and corrosion resistance of hot forming SAF2507 duplex stainless steel

采用XRD、SEM、EDS以及电化学测试等手段,研究不同热冲压成形温度下冲压成形SAF2507双相不锈钢析出相的析出规律,探讨热冲压成形温度、析出相对材料耐蚀性能的影响。研究表明:SAF2507双相不锈钢中χ相和σ相的析出温度范围为600~1000℃:温度<850℃以χ相析出为主,温度≥850℃时以σ相析出为主,温度≥950℃时α相逐渐消失,温度≥1050℃没有析出相。热冲压成形后的腐蚀电流密度和腐蚀速率随热冲压成形温度的变化呈增大—减小—增大规律,容抗弧呈减小—增大—减小规律变化,这与析出相随热冲压成形温度的变化规律相吻合。当热冲压成形温度为850~900℃时析出σ相数量最多,钝化膜稳定性最差。

The precipitation rule of precipitated phases and effects of hot forming temperature,precipitated phases on corrosion resistance of hot forming SAF2507 duplex stainless steel（ DSS） hot formed at different temperatures were studied by means of X-ray diffraction（ XRD）,scanning electron microscopy（ SEM）,EDS analysis and electrochemical testing methods. The results show that the χ phase of the steel is precipitated when the hot forming temperature is lower than 850 ℃,σ phase is precipitated when hot forming temperature is higher than or equal to 850 ℃,α phase gradually disappears when hot forming temperature is higher than or equal to 950 ℃,no precipitated phase is found when hot forming temperature higher than or equal to 1050 ℃. With the increasing of hot forming temperature,the corrosion current density and the corrosion rate of the steel first increase and then decrease and last increase,the capacitive reactance arc first decreases and then increases and last decreases,this is in agreement with the variation of the precipitated phase vs the hot stamping forming temperature. When the hot forming temperature is 850 ℃-900 ℃,the amount of the σ phase is the highest,and the stability of the passive film is the worst.