Incoloy800H合金晶界特征分布优化及其性能研究

发布时间：2018-06-17 06:22

  本文选题：Incoloy800H合金 + 晶界特征分布　； 参考：《南京理工大学》2017年硕士论文

【摘要】：Incoloy800H合金具有优异的高温强度、耐高温氧化及腐蚀能力,广泛地应用于石化工业领域。然而服役环境中的腐蚀性气氛常常会造成合金的腐蚀破坏,随着合金服役条件越加复杂苛刻,对合金的耐蚀性提出了更高的挑战。"晶界工程"是根据晶界设计与控制这一概念而提出的,通过形变热处理工艺优化合金中的晶界特征分布,进而改善合金与晶界相关的多种性能。而与晶界有关的应力腐蚀和晶间腐蚀是Incoloy800H合金失效的重要原因,因此,利用晶界工程处理来优化Incoloy800H合金的晶界特征分布是改善合金耐腐蚀性能的一个有效手段。本论文研究了变形量、退火工艺和加工道次对合金晶界特征分布的影响规律,从而确定了 Incoloy800H合金晶界工程的最佳形变热处理工艺参数,并进一步研究了晶界特征分布对合金力学性能和耐腐蚀性能的影响。主要结论如下:(1)根据对晶界特征分布的调控以及对晶间腐蚀倾向的改善效果,确定Incoloy800H合金晶界工程的最佳形变热处理工艺为15%冷轧变形量后在1050℃退火45min。(2)Incoloy800H合金经过形变热处理后,通过发生回复和再结晶,形成大量Σ3晶界,使得特殊晶界比例从45.53%提高到72.69%,并且打断了随机大角度晶界网络,从而实现了晶界特征分布的优化。(3)经过晶界工程优化的Incoloy800H合金的力学性能相对于母材得到了提高:抗拉强度提高了 6.7%,延伸率提高了11.3%;在600℃/250MPa条件下,蠕变寿命从251.9h提高到405.8h,稳态蠕变速率由1.84×10~(-7)s~(-1)减小到1.55×10~(-7)s~(-1)。(4)由于低ΣCSL(coincidence site lattice,Σ≤29)晶界相对于自由大角晶界来说有更好的晶间腐蚀抗力,同时被低ΣCSL晶界打断的晶界网络能够抑制晶间腐蚀扩展,因此经过晶界工程优化的合金的耐晶间腐蚀性能得到显著提高,腐蚀失重速率降低为实验母材的1/2。
[Abstract]:Incoloy 800H alloy is widely used in petrochemical industry because of its excellent high temperature strength, high temperature oxidation resistance and corrosion resistance. However, the corrosive atmosphere in the service environment often leads to the corrosion damage of the alloy. As the service conditions of the alloy become more complex and demanding, it poses a higher challenge to the corrosion resistance of the alloy. " Grain boundary engineering was proposed according to the concept of grain boundary design and control. The grain boundary characteristic distribution in the alloy was optimized by thermomechanical treatment process, and various properties related to grain boundary were improved. The stress corrosion and intergranular corrosion related to grain boundary are the important causes of incoloy 800H alloy failure. Therefore, it is an effective means to improve the corrosion resistance of incoloy 800H alloy by using grain boundary engineering treatment to optimize the grain boundary characteristic distribution of incoloy 800H alloy. In this paper, the effects of deformation, annealing process and pass on the grain boundary characteristic distribution of incoloy 800H alloy are studied, and the optimum parameters of deformation heat treatment for incoloy 800H alloy grain boundary engineering are determined. The effect of grain boundary characteristic distribution on the mechanical properties and corrosion resistance of the alloy was also studied. The main conclusions are as follows: (1) according to the regulation of grain boundary characteristic distribution and the improvement of intergranular corrosion tendency, The optimum thermomechanical treatment process for incoloy800H alloy grain boundary engineering was determined as 15% cold rolling deformation and annealed at 1050 鈩，

本文编号：2030052