CAJ | 학술논문

对两种低镍奥氏体不锈钢在温度950℃～1200℃进行拉伸试验和拉伸卸载试验，分析塑性材料在高温单轴拉伸过程中的几何失稳特性。结果表明，当载荷达到最大时，试样发生载荷失稳，此后再经历一段变形才发生几何失稳。载荷失稳之前，试样各处变形均匀；载荷失稳到几何失稳阶段，试样局部出现了不均匀变形，但这种局部不均匀并不立即发展为几何失稳。随着变形温度升高，载荷失稳真应变和加工硬化指数 n均无明显变化，且大小相近，表明载荷失稳应变受 n值控制；而几何失稳应变和应变速率敏感性系数 m都随温度升高而增大，表明 m值决定了载荷失稳到几何失稳阶段的应变，并且该应变是几何失稳应变的主要因素。
대량충저얼오씨체불수강재온도950℃～1200℃진행랍신시험화랍신사재시험，분석소성재료재고온단축랍신과정중적궤하실은특성。결과표명，당재하체도최대시，시양발생재하실은，차후재경력일단변형재발생궤하실은。재하실은지전，시양각처변형균균；재하실은도궤하실은계단，시양국부출현료불균균변형，단저충국부불균균병불립즉발전위궤하실은。수착변형온도승고，재하실은진응변화가공경화지수 n균무명현변화，차대소상근，표명재하실은응변수 n치공제；이궤하실은응변화응변속솔민감성계수 m도수온도승고이증대，표명 m치결정료재하실은도궤하실은계단적응변，병차해응변시궤하실은응변적주요인소。
The characteristics of high temperature geometrical instability of plastic materials have been investigated through the tensile test and tensile unload test of two low nickel austenite stainless steels at the temperatures of 950℃ ~1200℃ .The results show that the geometrical instability occurs after a period of uniform deformation ,rather than immediately upon load instability during high temperature tensile .The specimen deformation is uniform before load instability ,and is non-uniform in the local posi-tion of specimen from the load instability stage to the geometric instability ,while the local non-uniform deformation does not di-rectly lead to the instability .With the increasing of the deformation temperature ,there is little obvious variation for both load in-stability strain and strain hardening exponent n ,and the load instability true strain is close to the value of n .The results indicate that the load instability true strain depends on the value of n .Both the geometric instability strain and strain rate sensitivity coeffi-cient m increase with the increasing of the temperature ,and the value of m determines the strain from load instability to geometric instability ,which is the major factor for the geometric instability strain .