CAJ | 학술논문

通过高温热胀形特征分析，研究热冲压22MnB5合金在不同温度下的成形性，并利用Dynaform软件仿真验证。比较成形温度在800℃和700℃时样件的热胀形特征，结果表明，在800℃时成形，样件由于平面应变方向主应变过大，拉压应变区次应力为负值，造成拉伸破裂；在700℃下冲压成形的试件，各部分应变都处于安全区域，双向拉伸区域和拉伸-压缩复合区域的变形均匀，较前者成形性良好。另外，提出关于热成形先进高强度钢(Advanced high strength steel, AHSS)样件，其最佳成形温度不是现有文献报道的800～850℃的范围内，该结论为深入探索最佳成形温度、提高成形性提供了方向；建立成形前的快冷法(冷速不低于27℃/s)，降温到目标温度700℃左右冲压成形。试验证明：通过该方法，样件的成形性明显改善，微观结构更为致密。
통과고온열창형특정분석，연구열충압22MnB5합금재불동온도하적성형성，병이용Dynaform연건방진험증。비교성형온도재800℃화700℃시양건적열창형특정，결과표명，재800℃시성형，양건유우평면응변방향주응변과대，랍압응변구차응력위부치，조성랍신파렬；재700℃하충압성형적시건，각부분응변도처우안전구역，쌍향랍신구역화랍신-압축복합구역적변형균균，교전자성형성량호。령외，제출관우열성형선진고강도강(Advanced high strength steel, AHSS)양건，기최가성형온도불시현유문헌보도적800～850℃적범위내，해결론위심입탐색최가성형온도、제고성형성제공료방향；건립성형전적쾌랭법(랭속불저우27℃/s)，강온도목표온도700℃좌우충압성형。시험증명：통과해방법，양건적성형성명현개선，미관결구경위치밀。
Based on the high-temperature thermal expansion analysis, the formability at different temperature of hot-forming 22MnB5 is studied and also verified by Dynaform simulation. Comparing the thermal expansion characteristics at forming temperature 800℃ and 700℃, the results suggest that:Forming at 800℃, the sample results in a tensile rupture since the principal strain in plane strain direction is too large, while the secondary strain in tensile-compressive zone is negative; forming at 700℃, the formability is significantly improved since the strain of all parts remain in a safety area and sample has a uniform deformation in biaxial stretching region and tensile-compressive zone. In addition, this work puts forward that the optimized forming temperature of hot-forming advanced high strength steel(AHSS) sample is not in the range of 800℃ to 850℃ reported in present literatures. This conclusion provides directions for deep exploration of optimized forming temperature and improvement of formability. A rapid cooling method is designed to provide a cooling rate over 27℃/s, with which the sample is cooled to 700℃-the target temperature for quenching. The experiment shows that by this method, there is a significant improvement on the formability, and the microstructure is denser.