Effect of Shot Peening on the Intergranular Corrosion Susceptibility of a Novel Super304H Austenitic Stainless Steel
Effect of Shot Peening on the Intergranular Corrosion Susceptibility of a Novel Super304H Austenitic Stainless Steel
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DOI：
10.1007/s11665-015-1806-5
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发表时间：
2015
影响因子：
2.3
通讯作者：
R. Wang;Zhijun Zheng;Yan Gao
中科院分区：
文献类型：
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作者：
R. Wang;Zhijun Zheng;Yan Gao
采用x射线衍射法对Super304H奥氏体不锈钢在600、650和700℃喷丸强化和敏化处理2 h后的表面相组成进行了表征。采用双回路电化学电位动力学再激活法（DL-EPR）考察其致敏度（DOS），并用扫描电镜（SEM）观察其致敏后的形貌。结果表明：喷丸强化后，Super304H钢表面形成了纳米晶粒和应变诱发马氏体，并伴有残余压应力。在600 ~ 700℃敏化2 h后，表面残余压应力有明显的松弛，且残余压应力的产生与晶间腐蚀敏感性（IGCS）之间没有系统的相关性。由于喷丸试样中存在应变诱发马氏体，在600 ~ 650℃敏化2 h后，其IGCS远高于接收试样，且DOS随喷丸时间的增加和应变诱发马氏体含量的增加而增加。而喷丸强化的Super304H不锈钢在700℃敏化2h后，由于应变诱发马氏体的反向转变和Cr在高温下的快速扩散，使其在极短时间内修复了铬的损耗区，从而消除了IGCS。综上所述，在700℃高温下，喷丸强化在不到2 h的时间内促进了Super304H钢的脱敏。
The surface phase constituent of Super304H austenitic stainless steel, after shot peening and sensitization treatment at 600, 650, and 700 °C for 2 h, was characterized using x-ray diffraction method. The degree of sensitization (DOS) was investigated by means of double-loop electrochemical potentiokinetic reactivation (DL-EPR) test, and the morphology after DL-EPR test was observed by scanning electron microscopy (SEM). The results showed that nano-sized grains and strain-induced martensite together with compressive residual stress formed on the surface of Super304H steel after shot peening. Surface compressive residual stresses relaxed greatly after being sensitized at 600-700 °C for 2 h, and no systematic correlation was observed between the compressive residual stresses developed and the intergranular corrosion susceptibility (IGCS). Because of the occurrence of strain-induced martensite in the shot-peened specimens, their IGCS is much higher than that of the as-received specimen when being sensitized at 600-650 °C for 2 h. Besides, the DOS increased with the increasing of shot peening time and the content of strain-induced martensite. On the contrary, the IGCS of Super304H stainless steels subjected to shot peening was eliminated when being sensitized at 700 °C for 2 h because of the reverse transformation of strain-induced martensite and faster diffusion rate of Cr at higher temperature in ultrafine-grained austenite which had helped healing the chromium depletion zone in a very short time. In a word, shot peening promoted desensitization of Super304H steel in a time shorter than 2 h at higher temperature up to 700 °C.