Zr-Cr合金的微观组织与力学性能

发布时间：2018-06-15 20:25

  本文选题：锆铬合金 + 热变形　； 参考：《燕山大学》2015年硕士论文

【摘要】：Zr及Zr合金具有热中子吸收截面积小,密度小,优异的抗腐蚀、抗氧化和耐辐照等理化性能,主要应用在核工业。随着研究人员对Zr合金的进一步研究,发现其作为结构材料有很广泛的应用前景。Zr合金四种常见的组织中兼具强度和塑性的组织为等轴组织和双态组织。基于此,本文以Zr-Cr二元合金为研究对象,通过成分优化、热变形和热处理工艺使合金组织发生再结晶,获得双态组织或等轴组织,同时提高合金的强度和塑性。实验设计了一系列不同成分的ZrCr合金,通过真空非自耗电弧熔炼炉制备出合金锭,研究了合金成分对其组织和性能的影响。结果表明,少量的Cr添加到纯Zr中就能大幅度提高合金的强度。合金的强度随Cr含量的增加而增加,而塑性随合金中Cr含量的增加而降低。当Cr含量为1.8 at%时,合金具有较高的强度,抗拉强度为1058MPa,同时延伸率能达到9.6%。Cr含量继续增加到3 at%时,抗拉强度增加到1232MPa,延伸率为6.2%。根据实验分析,选定1.8 at%Cr合金做固溶时效和退火处理,研究其微观组织和力学性能之间的演变关系。实验发现,经900℃固溶水冷后,合金形成了等轴组织,抗拉强度和塑性较热轧态的都有提升,分别为1109MPa和11.0%。合金在随后的时效过程中,随时效温度的增加,合金的强度下降,塑性有了大幅度提升。合金在700℃,塑性达到了最好,延伸率为18.4%,强度还保持在818MPa。合金时效过程中强度下降的原因是固溶体α相中Cr含量的急剧下降,合金的畸变降低。退火后的合金强度下降,塑性得到了提升。当退火温度高于800℃时,合金开始发生部分再结晶,900℃合金的组织已完全为等轴状组织。
[Abstract]:Zr and Zr alloys are mainly used in nuclear industry because of their small thermal neutron absorption cross section, low density, excellent corrosion resistance, oxidation resistance and radiation resistance. With the further study of Zr alloy, it is found that Zr alloy is widely used as structural material. Among the four common microstructures of Zr alloy, the structures with both strength and plasticity are equiaxed and bi-state. Based on this, the Zr-Cr binary alloy was studied in this paper. The microstructure of Zr-Cr binary alloy was recrystallized by optimization of composition, hot deformation and heat treatment, and the double structure or equiaxed structure was obtained, and the strength and plasticity of the alloy were improved at the same time. A series of ZrCr alloys with different compositions were designed experimentally. Alloy ingots were prepared by vacuum non-consumable arc melting furnace. The effect of alloy composition on the microstructure and properties of ZrCr alloy was studied. The results show that the strength of the alloy can be greatly improved by adding a small amount of Cr to pure Zr. The strength of the alloy increases with the increase of Cr content, while the plasticity decreases with the increase of Cr content in the alloy. When Cr content is 1.8 at%, the tensile strength of the alloy is 1058 MPA, and the tensile strength increases to 1232 MPA and the elongation reaches 6.2 MPA when the content of Cr continues to increase to 3 at%. According to the experimental analysis, 1.8atCr alloy was selected for solution aging and annealing, and the evolutionary relationship between microstructure and mechanical properties was studied. It was found that the alloy formed equiaxed structure after water cooling at 900 鈩，

本文编号：2023503