热处理工艺对7%Cr钢显微组织及耐蚀性能的影响

doi:10.13251/j.issn.0254-6051.2021.04.008

摘要/Abstract

摘要： 利用质量损失法和电化学方法测试了3种不同组织类型的7%Cr钢在CO₂环境中的腐蚀行为,并通过EBSD和SKPM手段从晶界和表面电势角度分析了组织类型引起的耐蚀性能差异原因。结果显示:7%Cr钢轧态组织为贝氏体+铁素体,淬火态组织为淬火马氏体,正火态组织为铁素体+少量珠光体。试验钢的耐蚀性能排序为淬火态＞正火态＞轧态,试验钢产物膜中Cr元素的富集程度及其极化曲线自腐蚀电位均与此规律相符,试样表面最大电势差与此规律相反。轧制试样两相间存在电势差,易于形成原电池;淬火试样中Cr元素可通过晶界快速扩散至腐蚀位置形成产物膜;正火试样游离态Cr元素较少且高比例的大角度晶界不利于其扩散至腐蚀界面。

关键词: 中Cr钢, CO₂腐蚀, 晶界, 扫描开尔文探针显微镜

Abstract: Corrosion behavior of 7%Cr steel with three different types of microstructure in CO₂ environment was tested by mass loss method and electrochemical method.The reasons for the difference of corrosion resistance caused by microstructure type were analyzed from grain boundary and surface potentialby by means of electron back-scattered diffraction and scanning Kelvin probe microcope. The results show that the microstructure of the rolled 7%Cr steel is composed of bainite+ferrite, the quenched sample is composed of quenched martensite, and the normalized sample is composed of ferrite+a small amount of pearlite. The order of corrosion resistance of the tested steel is quenched>normalized>rolled, and the enrichment degree of Cr element in the product film of the tested steel and the self-corrosion potential of its polarization curve are consistent with this law, while the maximum potential difference on the surface of the sample is opposite. The existing potential difference between the two phases in the rolled sample is easy to form a galvanic cell; the Cr element in the quenched sample can quickly diffuse through the grain boundary to the corrosion position to form a product film; the free Cr in the normalized sample is less and the high proportion of high-angle grain boundary is not conducive to its diffusion to the corrosion interface.

Key words: medium Cr steel, CO₂ corrosion, grain boundary, scanning Kelvin probe microscope

中图分类号:

TG172.3

顾洋, 宋帅, 武会宾, 张志慧, 张鹏程. 热处理工艺对7%Cr钢显微组织及耐蚀性能的影响[J]. 金属热处理, 2021, 46(4): 42-48.

Gu Yang, Song Shuai, Wu Huibin, Zhang Zhihui, Zhang Pengcheng. Effect of heat treatment process on microstructure and corrosion resistance of 7%Cr steel[J]. Heat Treatment of Metals, 2021, 46(4): 42-48.

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