CAJ | 학술논문

在金属切削过程中,剧烈的大剪切变形可以产生具有超细晶结构的切屑,从而使其获得比本体材料更高的硬度和强度.文中比较了不同的金属和合金在各种刀具前角和切削速度下,切屑上产生的剪应变、切屑的微结构及硬度的变化规律.实验结果显示:随着刀具前角的减小,切屑的微结构显著细化,其硬度随之极大提高;切削速度的减小提高了切屑的硬度,但对其微结构的影响不甚明显;采用负前角刀具在较低的切削速度下能加工出具有超细晶结构和高硬度的切屑材料,而切削速度的提高将使大剪切变形引起的硬度增长变缓.
재금속절삭과정중,극렬적대전절변형가이산생구유초세정결구적절설,종이사기획득비본체재료경고적경도화강도.문중비교료불동적금속화합금재각충도구전각화절삭속도하,절설상산생적전응변、절설적미결구급경도적변화규률.실험결과현시:수착도구전각적감소,절설적미결구현저세화,기경도수지겁대제고;절삭속도적감소제고료절설적경도,단대기미결구적영향불심명현;채용부전각도구재교저적절삭속도하능가공출구유초세정결구화고경도적절설재료,이절삭속도적제고장사대전절변형인기적경도증장변완.
During the metal cutting process, ultrafine-grained chips may form owing to the severe shear deformation, thus resulting in higher hardness and strength for the chips. In this paper, the variations of the shear strain imposed on the chips as well as on the microstructure and the hardness of chips under the condition of different tool rake angles and various cutting velocities are investigated for different metals and alloys. Experimental results indicate that (1) with the decrease of the tool rake angle, the microstructure of chips are significantly refined and the hardness of chips is greatly improved;(2) the effect of the cutting velocity on the microstructure and the hardness is opposite to that of the tool rake angle;(3) ultrafine-grained chip materials with high hardness can be obtained by cutting with a negative tool rake angle at a lower cutting velocity;and (4) the increase in cutting velocity alleviates the improvement of hardness owing to the large shear deformation.