Effects of Different Cutting Processes on Characteristics of Cut Damage for the Third-Generation Automobile Medium-Mn Steel
Effects of Different Cutting Processes on Characteristics of Cut Damage for the Third-Generation Automobile Medium-Mn Steel
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DOI：
10.1002/srin.201700375
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发表时间：
2018-09-01
影响因子：
2.2
通讯作者：
Dong, Han
中科院分区：
文献类型：
--
作者：
Chang, Ying;Han, Shuo;Dong, Han
含有大分数亚稳奥氏体的第三代汽车中锰（TAMM）钢采用剪切、激光切割和线切割放电加工（WEDM）三种切割工艺进行切割。讨论了显微组织、显微硬度和拉伸性能，以分析切削过程对切削损伤的影响。结果表明，经过三种切削工艺处理的TAMM样品呈现出不同的微观结构。首先，塑性变形导致微孔伸长，剪切边的TRIP效应产生马氏体，降低成形性并成为潜在的开裂原因。其次，根据TAMM钢的连续冷却转变（CCT）曲线，发现激光切割边缘由于激光切割过程中的温度变化而发生马氏体转变。第三，线切割加工过程中不会出现马氏体和拉长的微孔。线切割边缘保持原有的微观结构。此外，剪切边缘和激光切割边缘子表面的显微硬度得到提高。剪切影响区约为1755μm，激光切割影响区约为250μm。然而，显微硬度几乎不受线切割加工工艺的影响。此外，拉伸位移受切削工艺的影响也很明显。线切割样品的拉伸性能最好。通过调整模具间隙可以改善剪切样品的拉伸性能。本文有利于TAMM钢切削工艺的选择和提高制造能力。
The third-generation automobile medium-Mn (TAMM) steel containing large-fractioned metastable austenite is cut by three cutting processes, such as shearing, laser-cutting, and wire-cut electrical discharge machining (WEDM). Microstructure, microhardness, and tensile properties are discussed to analyze the effect of cutting process on cut damage. The results show that the TAMM samples treated by three cutting processes present different microstructures. Firstly, microvoids are elongated by plastic deformation and martensite is generated due to TRIP effect for sheared edge, which decreases formability and become potential cracking reasons. Secondly, martensitic transformation is found for laser-cut edge due to temperature variation during laser-cutting, according to continuous cooling transformation (CCT) curve of TAMM steel. Thirdly, no martensite and elongated microvoids occur during WEDM. The WEDM edge keeps original microstructures. Furthermore, microhardness of sheared edge and laser-cut edge sub-surface is increased. Shear-affected zone is about 1755 mu m and laser-cut-affected zone is about 250 mu m. However, microhardness is nearly not influenced by WEDM process. Besides, tensile displacement is affected obviously by cutting process. The stretchability of WEDM sample is the best. Tensile properties of sheared sample can be improved by adjusting die clearance. This paper is favorable to select cutting process and improve manufacturing ability of TAMM steel.