喷丸和盐酸酸洗对2205双相不锈钢热轧板氧化层微观结构的影响

利用光学显微镜(OM)、X射线衍射(XRD)、扫描电镜(SEM)配合能谱仪(EDS)和X射线光电子能谱(XPS)研究了 2205双相不锈钢热轧板经过退火和喷丸处理后的氧化层组成和结构,并分析了盐酸及混酸(HNO₃+HF)酸洗后表面钝化膜微观组织结构,利用电化学测试手段分析了酸洗后钢的耐蚀性,进一步提出了热轧退火2205双相不锈钢板在喷丸和酸洗过程中氧化层去除演变模型。结果表明:喷丸处理对于2205双相不锈钢表层富Fe氧化物的去除效果明显,但是不能去除内层致密的富Cr氧化层。盐酸预酸洗由外向内可以进一步去除喷丸后致密氧化层,硝酸和氢氟酸终酸洗可去除退火产生的贫Cr层,使得钢表面形成富含Cr₂O₃的钝化膜。2205双相不锈钢经混酸终酸洗后表现出比盐酸预酸洗后更高的自腐蚀电位和更大的容抗弧半径,说明混酸酸洗有利于提高2205双相不锈钢的耐蚀性能。

Effect of shot peening and hydrochloric acid pickling on oxide layer microstructure of 2205 duplex stainless steel hot-rolled sheet

Optical microscopy( OM),X-ray diffraction( XRD),scanning electron microscopy( SEM),energy dispersive spectrometer( EDS) and X-ray photoelectron spectroscopy( XPS) were used to study the oxide layer microstructure of the 2205 duplex stainless steel hotrolled sheet after annealing and shot peening treatment,and to analyze the microstructure of the surface passive film after pickling with hydrochloric acid and mixed acid( HNO₃+ HF). The corrosion resistance of the steel after pickling was analyzed by using electrochemical testing methods. Further,an evolution model of oxide layer removal during shot peening and pickling of the hot rolled 2205 duplex steel sheet after annealing was proposed. The results show that the shot peening treatment has significant effect on the removal of Fe-rich oxide in the2205 duplex steel surface layer,but the dense Cr-rich oxide layer within the inner layer cannot be removed. Hydrochloric acid pre-pickling can further remove the dense oxide layer from outside to inside after shot peening,and the final pickling with nitric acid and hydrofluoric acid can remove the Cr-poor layer produced by annealing,so that a Cr₂O₃-rich passive film is formed on the steel surface. The 2205 duplex steel after mixed acid pickling shows higher self-corrosion potential and larger arc resistance radius than that of hydrochloric acid pre-acid pickling,indicating that mixed acid pickling is beneficial to improve the corrosion resistance of 2205 duplex stainless steel.