Residual Stress in Steel Fusion Welds Joined Using Low Transformation Temperature (LTT) Filler Material
Residual Stress in Steel Fusion Welds Joined Using Low Transformation Temperature (LTT) Filler Material
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DOI：
10.4028/www.scientific.net/msf.768-769.620
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发表时间：
2013-09
期刊：
影响因子：
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通讯作者：
J. Gibmeier;E. Obelode;J. Altenkirch;A. Kromm;T. Kannengiesser
中科院分区：
文献类型：
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作者：
J. Gibmeier;E. Obelode;J. Altenkirch;A. Kromm;T. Kannengiesser
焊接残余应力是工业部件结构完整性评估的主要关注点。奥氏体-马氏体转变产生的剪切应变和体积应变影响焊接过程中残余应力的产生。控制相变可以调整焊接残余应力。低转变温度 (LTT) 焊接填充材料表现出降低的 MS 温度，可以推迟相变。由延迟转变产生的相关应变补偿了热收缩应变，因此可以减少拉伸甚至引入压缩残余应力。在本文中，我们讨论了 15 毫米 S690Q 钢板与 LTT 填充材料（含 10 wt% Cr 和 Ni 含量从 8 到 12 wt% 不等）连接的三轴残余应力分布。使用互补同步加速器 X 射线和中子衍射应力分析，分别从马氏体和残余奥氏体的相特定晶格应变和相分数得出宏观残余应力。使用应力消除梳确定局部相特定的无应变晶格参数。研究表明，随着镍含量的增加，残余奥氏体的相分数增加。此外，与熔合区每个焊缝的镍含量无关，在纵向上发现了显着的残余压应力，这些残余应力由热影响区（HAZ）中的残余拉应力平衡。在焊缝横向和法向方向上，应力分布在性质上相似，但幅度较小。残余奥氏体量的增加降低了延迟相变期间剪切和体积应变产生的压缩应力，因此在降低MS温度的情况下没有观察到压缩的显着增加。
Welding residual stress is of major concern for structural integrity assessment in industrial components. Shear and volume strains resulting from the austenite-martensite-transformation affect the development of residual stress during welding. Controlling the phase transformation allows adjustment of the welding residual stress. Low transformation temperature (LTT) weld filler materials exhibiting reduced MS-temperatures allow postponing the phase transformation. The associated strain arising from the delayed transformation compensates for the thermal contraction strains and as such may reduce tensile or even introduce compressive residual stress. In this article we discuss the tri-axial residual stress distribution in 15 mm S690Q steel plates joined with LTT filler materials with 10 wt% Cr and a Ni-content that varies from 8 to 12 wt%. Using complementary synchrotron X-ray and neutron diffraction stress analysis the macroscopic residual stress was derived from the phase specific lattice strain and phase fraction of martensite and retained austenite, respectively. The local phase specific unstrained lattice parameters were determined using stress relieved combs. The investigation revealed increasing phase fraction of retained austenite with increasing Ni-content. Further, independent of the Ni-content in each weld in the fusion zone, significant compressive residual stresses were found in the longitudinal direction, which are balanced by tensile residual stresses in the heat affected zone (HAZ). In the weld transverse and normal direction the stress distribution is qualitatively similar but less in magnitude. The increased amount of retained austenite reduces the compressive stress arising from shear and volume strains during the delayed phase transformation and therefore no significant increase in compression was observed for decreasing MS-temperatures.