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Influence of mechanically induced hardening on the generation of welding residual stresses

机械诱导硬化对焊接残余应力产生的影响

基本信息

批准号：
273371116
负责人：
Dr.-Ing. Thomas Nitschke-Pagel
金额：
--
依托单位：
Institut für Füge- und Schweißtechnik
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2015
资助国家：
德国
起止时间：
2014-12-31 至 2021-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/273371116?language=en
关键词：
Influence mechanically induced hardening generation

项目摘要

When steels are welded, the large temperature difference between weld and base metal causes stresses which can lead to cyclic plastic deformation, especially in the heat-affected zone. This process directly affects the development of welding residual stresses, as these are often limited by the yield strength. Therefore, suboptimal modelling of the mechanical hardening can lead to discrepancies between numerically and experimentally determined welding residual stresses. In the first research project concerning this topic, the mechanical hardening behavior of welded high-alloy steels was studied, which are not subject to any phase transformations. In a continuation project, the analyses shall be extended to steels with phase transformations, which additionally affect the hardening state. Since high-strength phases are present, structural hardening effects superpose those of the mechanical hardening. Moreover, transformation plasticity occurs which accounts for additional mechanical hardening. Finally, it is unclear if and how a mechanical hardening state is transferred from one phase to another during a transformation.Therefore, the aim of the continuation project is to fill the knowledge gap which is responsible for the significant discrepancies between computationally and experimentally obtained residual stresses in welded steels with phase transformations. To this end, the material behavior of two structural steels with different yield strengths is characterized comprehensively. Based on these results, simulations will be performed using different material models, whose results have to be compared to experimentally obtained residual stresses and hardening effects. Eventually, the optimal way of modeling mechanical hardening in steels with phase transformations for computing realistic results by welding simulation will be identified.

当钢被焊接时，焊缝和基体金属之间的大温差会产生应力，这会导致循环塑性变形，特别是在热影响区。该过程直接影响焊接残余应力的发展，因为这些残余应力通常受到屈服强度的限制。因此，机械硬化的次优建模可能导致数值和实验确定的焊接残余应力之间的差异。在关于该主题的第一个研究项目中，研究了焊接高合金钢的机械硬化行为，这些钢不受任何相变的影响。在后续项目中，分析应扩展到具有相变的钢，这会额外影响硬化状态。由于存在高强度相，因此结构硬化效应叠加机械硬化效应。此外，发生相变塑性，这是额外的机械硬化的原因。最后，目前还不清楚，如果以及如何从一个阶段的机械硬化状态转移到另一个相变过程中，因此，继续项目的目的是填补知识的差距，这是负责计算和实验获得的焊接钢与相变的残余应力之间的显着差异。为此，两种不同屈服强度的结构钢的材料行为进行了全面的表征。基于这些结果，将使用不同的材料模型进行模拟，其结果必须与实验获得的残余应力和硬化效应进行比较。最后，将确定模拟钢中机械硬化与相变的最佳方式，以通过焊接模拟计算出逼真的结果。