Integration of metal additive manufacturing (AM) and cold spray (CS) technologies provide an unprecedented opportunity to manufacture coated material systems with complex geometrical features. The application of these material systems in functionally critical components requires adequate structural integrity, particularly in the presence of cyclic loading. This work researches the multiaxial fatigue (axial-torsional cyclic loading) behavior of a coated material system consisting of 15Cr-5Ni precipitation-hardening stainless steel (15-5 PH SS) substrate additively manufactured by direct metal laser sintering with a layer of chromium carbide nickel (CrC-Ni) barrier coating deposited by CS. The influence of AM and CS-induced residual stresses on fatigue performance of test specimens was thoroughly studied. Additionally, the effect of surface roughness and processes induced defects were considered to explain the crack growth mechanism. Stresses assessed by synchrotron X-ray diffraction indicated a substantial accumulation of residual stresses, particularly in the outer surface of the as-fabricated 15-5 PH SS specimens. The state of residual stress was changed notably following the deposition of CrC-Ni coating in the axial, hoop, and radial directions of the fatigue test specimen. Also, CS deposition of CrC-Ni coating caused significant improvement in the surface quality of the additively manufactured components. Fatigue test results indicated, CS deposition of CrC-Ni substantially enhances the fatigue life of the AM-produced 15-5 PH SS substrate in all loading conditions, particularly in the high cycle fatigue regime. The improvement in the fatigue life of the specimens with coating was associated with a reduction in equivalent residual stress at the substrate surface and improvement in the specimens' surface condition (i.e., reduced surface roughness). The fractographic analysis of the specimen indicated the cracks tend to initiate in the surface of both as-fabricated and cold-sprayed specimens. However, the mechanism of crack growth changed notably following the deposition of CrC-Ni coating. The cracks tended to propagate in the planes parallel or with a small deviation from the build layers of the AM-produced specimens. On the other hand, deposition of CrC-Ni coating increased the deviation of crack growth plane from the build layers of the substrate.

金属增材制造（AM）和冷喷涂（CS）技术的集成为制造具有复杂几何特征的涂层材料系统提供了前所未有的机会。这些材料系统在功能关键的组件中的应用要求足够的结构完整性，尤其是在存在周期性载荷的情况下。这项工作研究了由15Cr-5Ni沉淀硬化不锈钢（15-5 PH SS）基底组成的涂层材料系统的多轴疲劳（轴向扭转循环载荷）行为，该基底通过直接金属激光烧结与碳化铬层相加而成CS沉积的镍（CrC-Ni）阻挡涂层。彻底研究了AM和CS引起的残余应力对试样疲劳性能的影响。另外，考虑了表面粗糙度和加工引起的缺陷的影响，以解释裂纹扩展的机理。通过同步加速器X射线衍射评估的应力表明残余应力的大量积累，特别是在15-15 PH SS试样的外表面。残余应力的状态随着CrC-Ni涂层在疲劳测试样品的轴向，环向和径向方向上的沉积而显着变化。同样，CrC-Ni涂层的CS沉积引起了增材制造组件表面质量的显着改善。疲劳试验结果表明，CrC-Ni的CS沉积在所有负载条件下，特别是在高循环疲劳状态下，都大大提高了AM生产的15-5 PH SS衬底的疲劳寿命。带有涂层的样品的疲劳寿命的改善与减少基材表面等效残余应力和改善样品表面状况（即降低表面粗糙度）有关。样品的分形分析表明，裂纹易于在加工后和冷喷涂样品的表面产生。但是，随着CrC-Ni涂层的沉积，裂纹扩展的机理发生了显着变化。裂纹倾向于在平行于平面的平面中传播，或者与AM产生的标本的构建层略有偏差。另一方面，CrC-Ni涂层的沉积增加了裂纹扩展平面与基体构建层的偏离。