Microstructure and Residual Stress Analysis of Explosion Cladded Inconel 625 and ASME SA516-70 Carbon Steel Bimetal Plates

Rogério Varavallo,Jose Olivas,Pedro Brito,Vinicius Paes,Haroldo Cavalcanti Pinto,Vitor De Melo Moreira

doi:10.4028/www.scientific.net/amr.996.494

Abstract

In the present work the explosion welded joint produced between an Inconel 625 alloy and ASTM A516-70 carbon steel sheets was investigated. After welding, the cladded plates were submitted to stress relief annealing at 600 °C for 3 h. The cross section of the cladded plates was examined in both as welded and heat treated conditions by optical microscopy and scanning electron microscopy. The hardness profile across the cladded interface was determined and the residual stress state created as a consequence of the explosion welding process was determined by X-ray diffraction. The experimental results showed that the Inconel 625 alloy adhered well to the ASTM SA516-70 steel, demonstrating the viability of the explosion cladding process for producing bimetal plates of the mentioned alloys. In the as welded condition, metallography analysis indicated severe plastic deformation close to the cladded interface and a wavy morphology characteristic of high bond strength. Elevated tensile residual stresses were created as a result of the welding process and considerable stress relaxation was attained by application of the proposed heat treatment.

Highlights

In many engineering applications, structural materials require a combination of mechanical strength and corrosion resistance
The microstructure of the Inconel 625 base material is composed of equiaxed grains
This probably occurs due to extensive plastic deformation caused by the explosion welding process

Summary

Introduction

Structural materials require a combination of mechanical strength and corrosion resistance. While many grades of carbon steel offer adequate mechanical properties within a reasonable price, corrosion resistance requires the application of stainless steels, nickel or titanium alloys and often implies an increase in production costs. Because corrosion is essentially a surface phenomenon, an alternative to the application of bulk corrosion resistant materials is the use of composite metals produced by cladding processes, whereby the corrosion resistant material is joined with a less expensive base material combining low cost with adequate properties [1]. The bond between both metals involves intense plastic deformation at the interface, which commonly assumes a wavy morphology as a consequence [5, 6]

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