Influence of the surface finish on corrosion resistance of stainless steels through machining and remelting on weld bead

Jean Robert Pereira Rodrigues,Silvio Rogerio De Freitas Batista,Rubens Soeiro Gonçalves,Carmem Célia Francisco Do Nascimento,João Luis Meneses Barros,Louriel Oliveira Vilarinho

doi:10.4025/actascitechnol.v41i1.37732

Abstract

The TIG Dressing technique has been widely used for repairing cracks in welded structures when subjected to mechanical forces that induce localized fatigue, leading to the collapse during operation. However, this technique has not been used for studies in structures susceptible to corrosion. In addition to changing the microstructure, it is expected that this technique increases the corrosion resistance of the edge of the weld bead which is a vulnerable region to corrosion. Moreover, the machining technique has been widely used to improve the workpieces finishing and/or structures that have been subjected to repair by welding, improving the surface roughness, increasing the corrosion resistance of these structures when subjected to aggressive environments. Thus, this work will study the effects of finishing techniques using machining and welding on the edge of the weld bead joints of 410D ferritic stainless steels, making an evaluation by mass loss in the samples which will be subjected to corrosion by immersion in NaCl containing medium. It is expected that the finishing techniques can relieve tensile stresses increasing the corrosion resistance.

Highlights

The edge of the weld bead of the ferritic stainless steel Ace P410 D welded using austenitic wire ER 308 L features the microstructure of Figure 6
Mechanical grinding techniques used to improve the consistency between the weld bead and the plate had distinct surface finishing, which influenced the final result of the corrosion resistance
Corrosion resistance on the edge of the weld bead was, influenced by the way in which the samples were subjected to the corrosion test, constrained or unconstrained

Summary

Introduction

According to Roberge (2008), the economic loss caused by corrosion reaches several sectors directly and/or indirectly, increasing maintenance costs and protection processes such as surface coating, generating additional costs for the different productive sectors. Corrosion is generated by direct action of the aggressive agent on the metal. The corrosion reactions in metals can occur in different ways, being the aqueous medium the most frequent occurrence. Corrosion presents in three different stages: anodic process (passage of ions to the solution), displacement of electrons and ions (transfer of electrons from anodic regions to the cathodic by metal circuit and a diffusion of cations and anions in the solution), and the cathodic process (receive electrons by ions or molecules of the solution) (Roberge, 2008)

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