扭转冷作硬化的试验研究

拉伸冷作硬化技术已得到广泛的工程应用。由于拉伸过程中存在颈缩现象,不能充分发挥所有材料的应变强化能力,使其强化效果受到限制。扭转过程中变形是均匀的,可以最大限度地发挥所有材料的强化能力,其强化效果应该比拉伸更显著。本文对中强度的40Cr钢和LY12一CZ铝合金试件所进行的扭转冷作硬化试验结果表明,并非对所有金属材料都是如此,对于具有体心立方点阵结构的金属,其扭转强化能力受到韧—脆转变现象的限制。

Experimental Study on Torsion Cold-work Harderning

The technology of tension cold-work hardening has been widely applied in engineering, but its strengthening effect is limited by necking existing in the process of tension,with the strain strengthening ability of most part of material not being brought into full play. As torsional strain is well-distributed along a specimen and the strengthening ability of the whole material is brought into full play,the torsion strengthening ability of the material should be greater than its tension strengthening ability. But the results of torsion experiments with medium strength steel 40Cr and aluminium alloy Lyl2-CZ show that the circumstances do not remain the same for all the metals. The torsion strengthening ability of the metals with body-centred-cubic lattice structure is limited by the ductile-brittle transition.