材料期刊网

用光学显微镜(OM)、扫描电子显微镜(SEM)、电解萃取法、草酸电解实验、x射线衍射(XRD)和双环电化学动电位再活化法(DL-EPR)等方法,研究了固溶和稳定化处理工艺对Super304H钢的显微组织(包括晶粒度,析出相分布、数量和类型)及晶间腐蚀敏感性的影响.结果表明,经过1150℃x15 min固溶处理后Super304H钢的晶粒度维持在7-10级;经不同温度的稳定化处理后析出相的数量较固溶态明显增加,其中950℃仍为敏化温度,有大量M23C6(M=Fe,Cr)沿晶界析出;随着稳定化温度的升高Nb(C,N)的析出数量随之增加,抗晶间腐蚀性能不断提高;当温度达到1100℃时Nb(C,N)的析出量达到最多,其抗晶间腐蚀性能较固溶态有明显提高;1100℃处于Super304H钢的固溶温度范围,明显高于传统1Cr18Ni9Ti型不锈钢的稳定化温度900℃,说明Super304H钢供货态的固溶处理工艺实际上兼顾了固溶与稳定化的双重作用.

In order to investigate the influence of stabilization treatment on microstructure and intergranular corrosion(IGC) resistance of Super304H austenitic heat-resistant steel,the microstructure including grain size,carbide distribution,type and amount of the samples after solution and stabilization treatment were characterized by optical microscope,scanning electron microscopy,electrolytic extraction method and X-ray diffraction.The intergranular corrosion degree was evaluated by oxalic acid electrolytic etching method and double loop electrochemical potentiokinetic reactivation tests.The results show that the grain grade of Super304H can be maintained between level 7 and 10 when quenched at 1150℃ for 15 minutes.Compared with the solution state,the amount of precipitated phases increased significantly after stabilization treatment.What is more,there were many M23C6 precipitates along grain boundaries when stabilized at 950℃,indicating that 950℃ was still at sensitizing temperature for Super304H.The Nb (C,N) quantity and IGC resistance increased with the increase of stabilization temperature,and its IGC resistance was superior to the solution state when stabilizing temperature reached 1100℃,where the Nb (C,N) precipitated most Meanwhile the 1100℃ was in the range of solution temperature for Super304H and was much higher than the stabilization temperature of conventional 1Cr18Ni9Ti stainless steel.It can be drawn that the delivery state heat treatment of Super304H plays the dual function of solution and stabilization.