材料期刊网

Hot Deformation Behavior of Nickel-Based Superalloy GH4720

Li QU Jing-long , BI Zhong-nan , DU Jin-hui , WANG Min-qing , WANG Qing-zeng , ZHANG Ji

钢铁研究学报(英文版)

The hot deformation characteristics of GH4720Li alloy were studied at the temperature of 1100-1170 ℃ and strain rate of 001-1 s-1 using Gleeble hot compression tests. True stress-true strain curves and deformation microstructures were investigated. Constitutive equation was established using the hyperbolic law. Processing map for hot working was also developed on the basis of the variations of efficiency of power dissipation with temperature and strain rate. The results show that dynamic recrystallization is the dominant softening mechanism during hot deformation. Fully recrystallized grain is obtained at strain of 07 above 1130 ℃, and coarsening occurs above 1150 ℃. The mean deformation activation energy is determined to be 512 kJ/mol. According to the low activation energy value, high dissipation efficiency parameter and fine recrystallized microstructure, 1130 ℃ is chosen as the hot working temperature for GH4720Li alloy.

关键词: hot deformation , GH4720Li alloy , constitutive equation , processing map

New Technology for High Efficient Recovery of Precious Metals Six-component Alloy Wastes

DONG Wei , WU Xian , ZHANG Ji , CAI Xingshun

贵金属

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Finite Element Analysis of Die Geometry and Process Conditions Effects on Equal Channel Angular Extrusion for β-Titanium Alloy

SI Jia-yong , GAO Fan , ZHANG Ji

钢铁研究学报(英文版)

The finite element analysis was applied to evaluate the respective influences of die geometry and process conditions on plastic strain distribution for β-titanium (Ti-13V11Cr3Al) alloy during the equal channel angular extrusion (ECAE). It was found that optimum equal channel angular extrusion die geometry is strongly material dependent. Optimal strain homogeneity in the Ti-13V11Cr3Al alloy may be achieved at r (inner radius)=5 mm, R (outer radius)=3 mm. The equivalent plastic strain increases with increasing friction coefficient. And the better homogeneity of the equivalent plastic strain distribution can be achieved when friction coefficient value is lower. The faster the ram speed is, the lower the homogeneity of the equivalent plastic strain distribution is and the influence is slight. The back-pressure does not help to improve the plastic strain homogeneity, and the increasing temperature has a slightly favourable effect on the plastic strain homogeneity between 400 and 600 ℃.

关键词: equal channel angular extrusion , finite element analysis , die geometry , β-titanium