【作者】 张新生；

【导师】 许淳淳；

【作者基本信息】 北京化工大学 ， 材料学， 2002， 硕士

【摘要】 本文重点研究了冷加工与304不锈钢组织结构以及耐蚀性能的关系。采用铁素体测量仪测定马氏体相含量，利用透射电镜分析位错形态，首先研究了冷加工对304不锈钢微观组织结构的影响。将304不锈钢分别在加热+180℃和低温-70℃条件下进行不同程度拉伸，得到仅有位错增殖但不含马氏体相，以及位错和马氏体相共存的两种试样。通过慢应变速率方法，分别将上述两种试样在42％沸腾MgCl₂溶液中进行应力腐蚀实验，研究了冷加工变形对304不锈钢耐应力腐蚀性能的影响；分别测定上述两种试样在含氯离子介质中的滞后环曲线，进一步研究了冷加工变形对304不锈钢耐孔蚀性能的影响。 冷加工变形影响了304不锈钢的微观组织结构，研究的结果表明：在室温和低温-70℃条件下冷加工，以304为代表的亚稳态奥氏体不锈钢均能产生不同程度的马氏体相变，且在同种冷加工方式下，冷加工变形量越大，马氏体相变量亦越大；而在+180℃条件下拉伸变形，304不锈钢却不发生马氏体相变。同时，低温-70℃和加热+180℃条件下塑性变形均使304不锈钢中位错密度随变形量增大而增加。 组织的变化影响了304不锈钢耐应力腐蚀性能，研究的结果表明：加热+180℃条件下拉伸变形使304不锈钢在42％沸腾MgCl₂溶液中的应力腐蚀破裂敏感性下降；而低温-70℃条件下拉伸变形使304不锈钢在42％沸腾MgCl₂溶液中的应力腐蚀破裂敏感性经历一个先下降后上升的过程。 组织的变化影响了304不锈钢耐小孔腐蚀性能，研究的结果表明：加热+180℃条件下塑性变形使304不锈钢在MgCl₂介质中的孔蚀击穿电位略微正移；而低温-70℃条件下塑性变形使304不锈钢在MgCl₂介质中的孔蚀击穿电位负移，并呈波动状。北京化J二大学闷反士学位创仑文 马氏体相变影响了304不锈钢材料的耐蚀性能，研究的结果表明:马氏体相的存在使304不锈钢在42%沸腾MgCI，溶液中的应力腐蚀破裂敏感性增大;马氏体相的存在使304不锈钢在MgCI:介质中的耐孔蚀性能呈降低趋势。更多还原

【Abstract】 The relation between cold working and microstructure and corrosion resistance of 304 stainless steel(304SS) in MgCl2 solution has been investigated in this paper. The distribution of the dislocations was observed by transmission electron microscope and martensite phase content was determined using ferrmagnetometer. First, effect of cold working on microstructure of 304SS was studied. Specimen which had dislocation proliferation only was got by plastic deformation on 304SS at +180C and specimen which had dislocation proliferation and martensite phase was got by plastic deformation on 304SS at -70C. Second, effect of cold working on stress corrosion cracking(SCC) of 304SS in 42% boiling MgCb solution was studied by slow strain rate testing. Then, effect of cold working on pitting corrosion of 304SS in 0.5mol/L MgCl2 solution at 50 C was also studied by potentiodynamic polarization.The microstructure of 304SS was influenced by cold-working. The results showed that plastic deformation at -70 C and +180C both make the dislocation density of 304SS increase with the increase of deformation, and in 304SS deformed at -70 C, martensite phase transformation is induced and increases with the increase of deformation, whereas it is not at+180C.The SCC of 304SS was influenced by cold-working. The results showed that as the degree of drawing deformation at +180C increases, SCC susceptibility of 304SS in 42% boiling MgCl2 solution decreases, while as the degree of drawing deformation at -70 C increases, it decreases at first, then increases.The pitting corrosion of 304SS was influenced by cold-working. The results showed that as the degree of drawing deformation at +180C increases, the breakdown potential Eb of 304SS’s passive film in 0.5mol/L MgCl2 solution at 50 C becomes a little more positive, while as the degree of drawing deformation at -70 C increases, it becomes more negative.The corrosion resistance of 304SS was influenced by cold-working. The results showed that martensite phase makes both SCC susceptibility and pitting susceptibility of 304SS increase.更多还原