Indian Scientists Pioneer Novel Technique For Creating Strong Bimetallic Structures With Enhanced Properties

A new bi-metallic joining process has been developed by Indian researchers to produce a bimetallic composite made from copper and steel that is highly suitable for engineering applications.

This composite has outstanding thermal and electrical conductivity, making it ideal for various applications such as hydraulic pump components, cooling staves, hot-work tooling applications, guide plates, and heat exchangers.

The development of bimetallic structures has become increasingly important in the world of technological advancements. These structures are highly customizable and offer a unique combination of individual material properties, making them well-suited for a wide range of applications.

Research in this area has significant implications for various engineering applications where the thermal conductivity and strength of the components play a critical role.

The bi-metallic composite made from copper and steel exhibits excellent mechanical properties, exceptional corrosion resistance, and high thermal and electrical conductivity.

However, welding copper and steel together can be challenging due to the differences in their melting points, thermal conductivity, and thermal expansion properties. As a result, joining copper and stainless-steel bimetallic structures without defects has been difficult.

To overcome this challenge, researchers at the International Advanced Research Centre for Powder Metallurgy and New Materials (ARCI), an autonomous R&D centre of the Department of Science and Technology, have developed a novel bi-metallic joining process using a technique called laser powder bed fusion (L-PBF) or selective laser melting (SLM) technique of metal 3D printing.

This technique involves layer deposition by metal powder melting, which creates a small melt pool of stainless-steel powder with subsequent high cooling rates, limiting the intermixing of the stainless-steel melt on copper surface, the Ministry of Science and Technology said in a statement on Friday (24 March).

During the L-PBF process, the laser beam interacts with the metal, impacting the degree of intermixing between copper and steel.

The researchers have successfully demonstrated the formation of the interfacial microstructure and bonding mechanism and investigated the reason for achieving a strong interfacial bond.

Tensile behavior studies were conducted, and the results convinced the researchers of the strong copper-steel bimetallic bond at the interface.

Micrographs obtained through high magnification imaging facility showed the limited intermixing of the copper and steel-rich regions across the interface.

The diffusion of Fe, Cr, and Ni elements from the steel to the copper side led to solid solution strengthening of copper near the interface, with a gradient drop in hardness from the interface on the copper alloy side.

The bi-metallic joining process between stainless steel and copper alloy, using laser powder bed fusion (L-PBF) technique, has the potential to revolutionise the engineering industry by offering customisable and strong bimetallic structures with enhanced properties, the ministry said.