合金元素对17wt.%Cr铁素体不锈钢组织和性能的影响

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	合金元素对17wt.%Cr铁素体不锈钢组织和性能的影响
	李丽坤
学位类型	硕士
导师	刘实
	2010
学位授予单位	中国科学院金属研究所
学位授予地点	北京
学位专业	材料加工工程
关键词	17wt.%cr铁素体不锈钢组织第二相耐蚀性能成型性能
摘要	"近年来，随着镍资源供应的紧张，镍价不断提高。为了降低成本，各国日益重视开发和应用节镍不锈钢，其中铁素体不锈钢是一个重要发展方向。但是，由于铁素体不锈钢存在对晶间腐蚀敏感，成型性差，室温和低温韧性差，焊接性差等缺点，严重制约了其广泛应用。为了提高铁素体不锈钢的耐晶间腐蚀性能和成型性能，本文主要研究了Ti，Nb，Mo，La等合金元素对17wt.%Cr铁素体不锈钢组织、耐蚀性能和成型性能的影响。采用真空感应炉熔炼的方法制备了17wt.%Cr超纯铁素体不锈钢。通过OM，XRD，SEM，EPMA，TEM等方法，研究了Ti，Nb，Mo，La等合金元素对17wt.%Cr铁素体不锈钢组织的影响。结果表明，在合金中，Ti主要以第二相TiN的形式存在，Nb一部分以固溶形式存在，一部分以第二相NbC和Fe2Nb的形式存在，Mo主要以固溶的形式存在；添加合金元素后，铸态组织都有所改善，其中复合添加Ti+Nb+Mo的效果最好，晶粒为等轴晶，且最细小；添加Ti，Nb，Mo合金元素后，合金的再结晶温度提高，晶粒细化，添加La后，合金的再结晶温度降低。采用动电位极化曲线和动电位再活化法研究了Ti，Nb，Mo，La等合金元素对17wt.%Cr铁素体不锈钢耐蚀性能的影响。结果表明，Nb和Mo明显降低合金的钝化电位，尤其是Mo；单独添加Nb和复合添加Ti+Nb能有效降低合金的晶间腐蚀敏感性，复合添加Ti+Nb+Mo和Ti+Nb+Mo+La能有效抑制合金晶间腐蚀。采用塑性应变比r和加工硬化指数n表征Ti，Nb，Mo，La等合金元素对17wt.%Cr铁素体不锈钢成型性能的影响。结果表明，添加0.18%Nb和0.06%Ti+0.12%Nb能明显提高合金塑性应变比加权平均值，Mo和La的加入降低Δr值，尤其是La；添加Ti和Nb均能提高其加工硬化指数，添加0.18%Nb时，合金的值加工硬化指数加权平均值最高，为0.2481。关键词：17wt.%Cr铁素体不锈钢，组织，第二相，耐蚀性能，成型性能"
其他摘要	"Effects of alloying elements on structure and properties of 17wt.%Cr ferritic stainless steels Likun Li (Materials processing) Supervised by Prof. Shi Liu In recent years, for lack of nickel resource, stainless steels with less nickel have attracted abroad attention, especially ferritic stainless steels. However, ferritic stainless steels are susceptible to intergranular corrosion, and their formability, weld performance and toughness are poor. On the purpose of improving the properties of ferritic stainless steels, the effects of Ti, Nb, Mo and La on the structure, corrosin resistance and formability of 17wt.%Cr ferritic stainless steels are mainly studied in this dissertation. The 17wt.%Cr ultra-pure ferritic stainless steels were prepared in a vacuum induction furnace. Effects of Ti, Nb, Mo and La on the structrue of ferritic stainless steels were investigated by OM, XRD, SEM, EPMA and TEM. The results indicate that the main secondary phases are TiN, NbC and Fe2Nb. The as-cast structure is improved as results of adding Ti, Nb, Mo and La, and the as-cast structure of ferritic stainless steels with Ti+Nb+Mo is the best. The recrystallization temperature increases and crystal grains are refined because of the addition of Ti, Nb and Mo, while the recrystallization temperature decreases as a restult of the addition of La. Anodic polarization curves and electrochemical potentiokinetic reactivation ratio were measured in order to study effects of Ti, Nb, Mo and La on the corrosin resistance of 17wt.%Cr ferritic stainless steels. EP decreases due to the addition of Mo and Nb, especially Mo. Bacause of the addition of Nb and Ti+Nb, intergranular corrosion resistance is improved a lot. Further more, intergranular corrosion is almost avoided as results of adding Ti+Nb+Mo and Ti+Nb+Mo+La. On the purpose of investigating effects of Ti, Nb, Mo and La on the formability of 17wt.%Cr ferritic stainless steels, plastic strain ratio r and tensile strain hardening exponent n were measured. The results indicate that r-value increases due to the addition of 0.18%Nb and 0.06%Ti+0.12%Nb. The Δr-value decreases after adding Mo and La, especially La. As results of adding Ti and Nb, n-value improves. The n-value of the alloy with 0.18%Nb is 0.2481, which is the highest. Key words: 17wt.%Cr ferritic stainless steels, structure, secondary phase, corrosion resistance, formability"
文献类型	学位论文
条目标识符	http://ir.imr.ac.cn/handle/321006/64212
专题	中国科学院金属研究所
推荐引用方式 GB/T 7714	李丽坤. 合金元素对17wt.%Cr铁素体不锈钢组织和性能的影响[D]. 北京. 中国科学院金属研究所,2010.