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研究低温(77K)多向锻造锆-4合金累积应变为1.48,2.96,4.44和5.91时的力学性能和组织演变。通过万能拉伸测试和维氏硬度实验测得多向锻造合金的力学性能。相对于原始合金,当锆-4合金变形的累积变形为5.91时,其极限抗拉强度从474MPa提高到717MPa,维氏硬度从HV 190提高到HV 238。然而,由于锆-4合金的低应变硬化,其延展性显著降低(18%~3.5%)。变形合金强度和硬度的提高是因为多向锻造引起的晶粒尺寸效应和高的位错密度。采用光学显微镜和透射电镜表征变形试样的显微组织演化。当累积应变为5.91时,经12次多向锻造后合金的微观组织演化主要是超细晶的形成,其平均晶粒尺寸为150~250nm。
The mechanical properties and microstructure evolution of low-temperature (77K) multi-directional forged zirconium-4 alloy with cumulative strain of 1.48, 2.96, 4.44 and 5.91 were investigated. The mechanical properties of multi-directional forged alloy were measured by universal tensile test and Vickers hardness test. When the cumulative deformation of zirconium-4 alloy is 5.91 with respect to the original alloy, the ultimate tensile strength increases from 474 MPa to 717 MPa, and the Vickers hardness increases from HV 190 to HV 238. However, ductility is significantly reduced (18% -3.5%) due to the low strain hardening of the zirconium-4 alloy. The increase in strength and hardness of the deformed alloy is due to the effect of grain size due to multi-directional forging and high dislocation density. The microstructural evolution of the deformed specimens was characterized by light microscopy and transmission electron microscopy. When the cumulative strain is 5.91, the microstructure evolution of the alloy after 12 multi-directional forging is mainly the formation of ultrafine grain with the average grain size of 150-250nm.