Joining immiscible materials such as copper and stainless steel together is a significant concern due to distinct mechanical and metallurgical properties across the joint line, such as melting points, the coefficient of linear thermal expansion, and thermal conductivity. The joint properties of copper to stainless steel welds are in great demand for various mechanical components of the international thermonuclear experimental reactor, ultra-high vacuum system, plan wave linear-accelerator or linac structure, and heat exchanger. These dissimilar-metals joints offer excellent flexibility in design and production, leading to a robust structure for many cutting-edge applications. Hence, the present article reviews the copper to stainless steel joining mechanism under different solid-state processing conditions. The present understanding says that defect-free strong joints between the dissimilar metals are systematically possible. Apart from this understanding, the authors have identified and highlighted the gaps in the research exploration to date. Moreover, a sustainable methodology to achieve a desirable weld of copper to stainless steel depends on favorable processing conditions.

The objective behind the present study is to explore the joint behavior of continuous wave fiber laser welded dissimilar material of AISI 304L stainless steel to electrolytic tough pitch copper plate. The focus is to identify the weld condition which would provide better intermixing of both materials. An experimental approach is adopted and the weld quality is assessed on the scale of mechanical and metallurgical examinations such as tensile test, optical microscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The EDX analysis confirms the inter-diffusion of Cu and SS inside the weld pool. The high dilution of Cu in weld pool showed transition zone with an area of dense Cu particle near the interface. However, the lower dilution of Cu shifts the transition zone towards the upper side of the weld pool. Interestingly, lower dilution of Cu in the fusion zone represents high static tensile strength wherein, the solidification crack at the fusion zone is observed while laser beam displacement towards the SS side. Moreover, maximum joint efficiency of 99% having ultimate tensile strength of 224 MPa reported when laser source focused at the butt line.