The strain fields present during the bending of ultra-high strength steels
The strain fields present during the bending of ultra-high strength steels
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超高强度钢弯曲过程中存在的应变场
DOI：
10.1016/j.proeng.2017.10.889
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发表时间：
2017
期刊：
影响因子：
--
通讯作者：
Hazra S
中科院分区：
文献类型：
--
作者：
Hazra S
超高强度钢（UHSS）的极限抗拉强度大于1GPa。通常，它们的环境温度伸长率小于10%，因此，它们很少用于冲压应用。然而，对运输部门建造的结构的重量减轻的持续需求意味着这种材料是有吸引力的，因为它们可以用于具有较薄横截面的部件，同时保持所需的使用性能。克服这些材料的环境温度延展性的一种方法是将它们辊轧成形，特别是使用新兴的柔性辊轧成形技术。使用数控驱动器，每个机架上的轧辊设计有足够的自由度，以形成弯曲的部件，沿其长度沿着变化深度和宽度。这使得柔性辊压成型部件对运输行业特别是汽车行业具有吸引力。辊轧成形通过增量局部弯曲使材料变形，已知这抑制颈缩响应，导致比拉伸变形更高的变形。最近的工作，如Le Maoquet，Thuillier & Manach，Eng. Frac.机械、第76卷，第1202页（2009年），侧重于开发韧性断裂模型来解释失效，但其验证仅限于载荷位移和表面应变数据。本文旨在更全面地研究弯曲过程中的应变场。利用数字图像相关技术，测量了超高强度钢弯曲过程中宏观应变沿板厚的分布和微观组织中的应变分配。这些数据提供了弯曲过程中应变分布的详细解释。
Ultra high strength steels (UHSS) have an ultimate tensile strength of greater than 1GPa. Typically, their ambient temperature elongation is less than 10% and as a result, they are rarely used in stamping applications. However, the continuous demand for the weight reduction of structures built for the transport sector means that such materials are attractive because they can be used for parts with thinner cross-sections while maintaining required in-service performance. One way to overcome the ambient temperature ductility of these materials is to roll-form them, particularly with emerging flexible roll forming technology. Using numerically-controlled actuators, the rolls on each stand are designed with sufficient degrees of freedom to form parts that curve, vary in depth and width along their lengths. This makes flexibly roll-formed parts attractive to the transport, particularly the automotive, sector. Roll forming deforms a material through incremental, localised bending, which is known to suppress the necking response, resulting in deformations that are higher than in stretch deformation. Recent work, such as Le Maoût, Thuillier & Manach,Eng. Frac. Mech., Vol. 76, p.1202 (2009), focussed on the development of ductile fracture models to explain failure but their validation was limited to load displacement and surface strain data. This work aims to characterise the strain field during bending more comprehensively. Using the digital image correlation technique, the macroscopic strain distribution in UHSS in the thickness of the sheet and the strain partitioning in its microstructure is measured during bending. The data provides a detailed explanation of the strain distribution during bending.