Inconel625合金大规格管棒材挤压过程的组织与性能演变

发布时间：2018-01-02 15:18

本文关键词：Inconel625合金大规格管棒材挤压过程的组织与性能演变　出处：《兰州理工大学》2016年硕士论文　论文类型：学位论文

更多相关文章： 高温合金 Inconel625 热挤压 组织性能

【摘要】：Inconel625合金是以钼、铌为主要强化元素的固溶强化型镍基变形高温合金,具有优良的耐腐蚀和高氧化性能,从低温到980℃均具有良好的拉伸性能和疲劳性能,并且耐盐雾气氛下的应力腐蚀。但限于镍基合金成形温度区间窄及变形抗力大等固有属性,实际生产中大口径管棒材的成型技术还不完善。本文通过热挤压的方法得到大口径Inconel625合金管棒材,并在此基础上分析不同成型参数对其成形性的影响,得到合理热挤压工艺参数。通过各种分析工具、力学试样及电化学实验研究不同挤压参数下,材料的组织和性能的变化规律。在研究热挤压前后Inconel625合金显微组织性能的变化中发现,挤压前后均有Nb偏析的存在。通过SEM和TEM等分析工具,发现热挤压前的加热过程中产生M23C6碳化物。热挤压后,材料发生完全再结晶,组织均匀,但仍有部分碳化物保留在晶界;织构密度明显降低;力学性能整体而言有所提升;耐腐蚀性能有所改善。随着挤压比的增大,变形热导致实际挤压温度升高,再结晶平均晶粒尺寸明显增大;织构密度减小;高温使得晶界碳化物大量溶解,断口二次裂纹大量减少,固溶强化作用增强,强度升高,塑性下降;耐腐蚀性能也呈下降趋势。同时提高挤压比和挤压速度,虽然变形热会增多,但高速挤压使得二次相溶解和再结晶晶粒长大没有时间进行。再结晶晶粒尺寸也呈增大趋势,但幅度较小;相比于只增大挤压比,晶界碳化物溶解量明显减少,断口二次裂纹增多;强度小幅增加,塑性小幅下降。耐腐蚀性处于中等水平。
[Abstract]:Inconel625 alloy is molybdenum, niobium solid solution strengthened nickel based superalloy mainly strengthening element, has excellent corrosion resistance and high oxidation resistance, from low temperature to 980 DEG C have tensile properties and good fatigue resistance, corrosion resistance and stress of salt spray atmosphere. But limited to nickel base alloy forming narrow temperature range and high resistance to deformation and other inherent properties, molding technology and actual production in large caliber pipe bar is not perfect. The large diameter Inconel625 alloy tube bar by hot extrusion molding, analysis of different parameters on the formability of the impact and on the basis of reasonable hot extrusion process through various parameters. Analysis tools, research samples and electrochemical experimental mechanics different extrusion parameters, variation of microstructure and mechanical properties of the material. The changes in microstructure and mechanical properties of Inconel625 alloy before and after hot extrusion in the study, Extrusion both before and after the Nb segregation. Through SEM and TEM analysis tools, found to produce M23C6 carbides in the heating process of hot extrusion. After hot extrusion, materials complete recrystallization microstructure, but there are still some carbide retained in the grain boundary; texture density decreased significantly; the mechanical properties of the whole improved corrosion resistance; the performance has been improved. With the increase of the extrusion ratio, thermal deformation cause actual extrusion temperature, the recrystallization of the average grain size increases; texture density decreases; the high temperature makes the grain boundary carbides dissolved, reducing the number of fracture two crack, solid solution strengthening effect is enhanced, the strength increased, the ductility decreases; the corrosion resistance also showed a trend of decline. At the same time. The increasing of extrusion ratio and extrusion speed, while the thermal deformation will increase, but the high speed extrusion makes two phase dissolution and recrystallization grains grow up in no time. The recrystallization grain size Inch also showed an increasing trend, but the amplitude was small. Compared with increasing extrusion ratio only, the amount of carbide dissolved in grain boundary decreased significantly, the cracks increased two times, the strength increased slightly, and the ductility decreased slightly. Corrosion resistance was at a medium level.

【学位授予单位】：兰州理工大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TG132.3;TG376

【参考文献】