限定型高压扭转过程变形研究

Analysis of deformation in destined high pressure torsion

文章制备了一套限定型高压扭转(HPT)设备。采用HPT处理纯铜试样,对比处理前后试样几何尺寸,观察试样与砧头之间的相对滑动,结果表明,HPT处理前后试样厚度变化小于5%,试样端面和模具不发生相对滑动。用量纲分析和有限元方法分析试样的变形,得到切应变和厚度/直径、压力/材料弹性模量以及模具侧面的摩擦状况相关;直径8 mm厚0.86 mm纯铜试样上r<3.2 mm区域的变形可以用纯扭转来描述。

A holding apparatus for destined high pressure torsion（HPT） treatment was designed and manufactured. Geometrical sizes of pure copper samples before and after HPT were compared. The slide between the sample and the apparatus was observed. It is concluded that the thickness change is less than 5% and there is no slide between the sample surface and the apparatus. Dimensional analysis and the finite element method were employed to analyze the shear strain. Dimensional analysis shows that the shear strains of samples are correlated with the ratio of thickness to diameter, the ratio of pressure to elastic modulus, and friction condition of the apparatus side. The FEM results indicate that the ideal torsion formula can describe the shear strain of the pure copper sample with the diameter 8 mm and thickness 0.86 mm in the area r〈3.2 mm.