Abstract It is generally believed that because of deposition at a temperature lower than the melting point, and high impact velocity of particles in cold spray printing, beneficial compressive residual stresses are induced in the substrate and coating. We have examined this general belief by identifying four major factors influencing the formation of residual stresses: coating and impact-induced temperatures, thermal mismatch of coat and substrate, heat transfer rate, and impact peening effect. A series of experiments is developed to allow studying these effects separately and to investigate their interactions. It is concluded that the heat input and heat transfer rate are the key controlling factors in the sign of the residual stress. Furthermore, we show that one can control the formation of residual stress to a desirable pattern, i.e., compressive in both the coating and the substrate near the interface. Using such parameters, two distinct residual stresses, tensile and compressive, were produced in the Al7075 coated AZ31B sheet. Further, the quality of the two coatings is measured through computerized tomography, surface roughness, and hardness measurements. It is shown that the density and hardness of the compressive samples are higher, while the roughness is lower than the tensile sample.

中文翻译：

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冷喷打印残余应力的定制

摘要 人们普遍认为，由于在低于熔点的温度下沉积，并且冷喷涂中颗粒的冲击速度较高，因此在基材和涂层中会产生有益的残余压应力。我们通过确定影响残余应力形成的四个主要因素来检验这一普遍看法：涂层和冲击引起的温度、涂层和基材的热失配、传热率和冲击喷丸效果。开发了一系列实验以允许分别研究这些影响并研究它们的相互作用。得出的结论是，热量输入和传热速率是残余应力符号的关键控制因素。此外，我们表明可以将残余应力的形成控制为所需的模式，即，界面附近的涂层和基材均受压。使用这些参数，在 Al7075 涂层的 AZ31B 板材中产生了两种不同的残余应力，拉伸和压缩。此外，两种涂层的质量通过计算机断层扫描、表面粗糙度和硬度测量进行测量。结果表明，压缩样品的密度和硬度较高，而粗糙度低于拉伸样品。