Residual stress is a crucial element in determining the integrity of parts and lifetime of additively manufactured structures. In stainless steel and Ti-6Al-4V fabricated joints, residual stress causes cracking and delamination of the brittle intermetallic joint interface. Knowledge of the degree of residual stress at the joint interface is, therefore, important; however, the available information is limited owing to the joint’s brittle nature and its high failure susceptibility. In this study, the residual stress distribution during the deposition of 17-4PH stainless steel on Ti-6Al-4V alloy was predicted using Simufact additive software based on the finite element modeling technique. A sharp stress gradient was revealed at the joint interface, with compressive stress on the Ti-6Al-4V side and tensile stress on the 17-4PH side. This distribution is attributed to the large difference in the coefficients of thermal expansion of the two metals. The 17-4PH side exhibited maximum equivalent stress of 500 MPa, which was twice that of the Ti-6Al-4V side (240 MPa). This showed good correlation with the thermal residual stress calculations of the alloys. The thermal history predicted via simulation at the joint interface was within the temperature range of 368–477 °C and was highly congruent with that obtained in the actual experiment, approximately 300–450 °C. In the actual experiment, joint delamination occurred, ascribable to the residual stress accumulation and multiple additive manufacturing (AM) thermal cycles on the brittle FeTi and Fe₂Ti intermetallic joint interface. The build deflected to the side at an angle of 0.708° after the simulation. This study could serve as a valid reference for engineers to understand the residual stress development in 17-4PH and Ti-6Al-4V joints fabricated with AM.

中文翻译：

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钛合金与17-4PH不锈钢接头界面残余应力的有限元建模

残余应力是决定零件完整性和增材制造结构寿命的关键因素。在不锈钢和Ti-6Al-4V制成的接头中，残余应力会导致脆性金属间化合物接头界面破裂和分层。因此，了解关节界面残余应力的程度很重要；但是，由于关节的脆性和较高的失效敏感性，因此可获得的信息有限。在这项研究中，使用Simufact添加剂软件基于有限元建模技术预测了17-4PH不锈钢在Ti-6Al-4V合金上的沉积过程中的残余应力分布。在接头界面处显示出明显的应力梯度，其中Ti-6Al-4V侧为压应力，而17-4PH侧为拉应力。该分布归因于两种金属的热膨胀系数的巨大差异。17-4PH侧的最大等效应力为500 MPa，是Ti-6Al-4V侧的最大等效应力（240 MPa）的两倍。这与合金的热残余应力计算显示出良好的相关性。通过模拟在接头界面处预测的热历史在368–477°C的温度范围内，与实际实验中获得的大约300–450°C高度一致。在实际实验中，由于脆性FeTi和Fe上的残余应力积累和多次加法制造（AM）热循环，发生了联合分层。17-4PH侧的最大等效应力为500 MPa，是Ti-6Al-4V侧的最大等效应力（240 MPa）的两倍。这与合金的热残余应力计算显示出良好的相关性。通过模拟在接头界面处预测的热历史在368–477°C的温度范围内，与实际实验中获得的大约300–450°C高度一致。在实际实验中，由于脆性FeTi和Fe上的残余应力积累和多次加法制造（AM）热循环，发生了联合分层。17-4PH侧的最大等效应力为500 MPa，是Ti-6Al-4V侧的最大等效应力（240 MPa）的两倍。这与合金的热残余应力计算显示出良好的相关性。通过模拟在接头界面处预测的热历史在368–477°C的温度范围内，与实际实验中获得的大约300–450°C高度一致。在实际实验中，由于脆性FeTi和Fe上的残余应力积累和多次加法制造（AM）热循环，发生了联合分层。通过模拟在接头界面处预测的热历史在368–477°C的温度范围内，与实际实验中获得的大约300–450°C高度一致。在实际实验中，由于脆性FeTi和Fe上的残余应力积累和多次加法制造（AM）热循环，发生了联合分层。通过模拟在接头界面处预测的热历史在368–477°C的温度范围内，与实际实验中获得的大约300–450°C高度一致。在实际实验中，由于脆性FeTi和Fe上的残余应力积累和多次加法制造（AM）热循环，发生了联合分层。₂ Ti金属间接头界面。模拟后，构造以0.708°的角度偏向侧面。这项研究可以为工程师了解AM制造的17-4PH和Ti-6Al-4V接头的残余应力发展提供有效参考。