Numerical simulation of residual stress and deformation for submerged arc welding of Q690D high strength low alloy steel thick plate

The finite element simulation software SYSWELD is used to numerically simulate the temperature field,residual stress field,and welding deformation of Q690D thick plate multi-layer and multi-pass welding under different welding heat input and groove angles.The simulation results show that as the welding heat input increases,the peak temperature during the welding process is higher,and the residual stress increases,they are all between 330–340 MPa,and the residual stress is concentrated in the area near the weld.The hole-drilling method is used to measure the actual welding residual stress,and the measured data is in good agreement with the simulated value.The type of post-welding deformation is angular deformation,and as the welding heat input increases,the maximum deformation also increases.It shows smaller residual stress and deformation when the groove angle is 40°under the same heat input.In engineering applications,under the premise of guaranteeing welding quality,smaller heat input and 40°groove angle should be used.

超高强度钢的发展及展望

结合超高强度钢在航空领域的广泛应用,介绍了航空用超高强度钢的发展现状,总结了国内外超高强度钢的发展思路及特点。目前,300M钢以及AerMet100钢以其较高的强度及韧性,应用于飞机的起落架和联接螺栓等关键部件上。阐述了当前的热处理加工方法,与传统的淬火-低温回火(Q-T)热处理工艺相比,采用淬火-碳分配(Q-P)以及淬火-碳分配-回火沉淀(Q-P-T)工艺,将获得更加细小的晶粒以及更高的强韧性。分析了超高强度钢今后的大致发展方向。

逆转变+Q&P复合工艺对低合金高强钢组织和性能的影响

利用SEM、XRD分析及拉伸试验,研究了逆转变+淬火-配分(ART+Q&P)复合工艺对完全淬火后0.22C-2.0Mn-1.8Si钢组织性能的影响。结果表明:经ART+Q&P工艺处理后,该钢组织为亚温铁素体、贝氏体/马氏体和均匀分布的残留奥氏体。逆转变奥氏体富集Mn、C元素,淬火-配分过程中碳自马氏体配分至残留奥氏体时二次富C,使其稳定化,因此该钢室温下获得残留奥氏体的含量超过15%。在拉伸变形过程中残留奥氏体转变成马氏体的TRIP效应,使得钢材在变形过程中获得稳定的加工硬化能力,实现了良好的强塑性结合,抗拉强度达到1233 MPa,屈服强度为893 MPa,均匀伸长率29.6%,强塑积高达36 GPa·%以上。