Investigating mechanical properties of dissimilar welds of stainless steel 316L and Inconel 625 for high temperature corrosion applications

Author: Daniel Shore

  • Thesis download: available for open access on 22 Mar 2025.

Shore, Daniel, 2023 Investigating mechanical properties of dissimilar welds of stainless steel 316L and Inconel 625 for high temperature corrosion applications, Flinders University, College of Science and Engineering

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Dissimilar welding is a common practice in industrial systems. The process allows for

specific or improved mechanical and chemical properties to be applied over specific sections,

allowing for specific environments to be sustainable and costs to be reduced. Concentrated

solar thermal power plants are one such system, which requires stainless steel 316L and

Inconel 625 to be dissimilarly weld. The differing thermal and corrosive conditions that are

present at different points, require the different properties provided by each material. The

process of welding is similar to applying a heat treatment and thus may alter the material.

This study aims to explore if the welding process has caused a mechanical or chemical

alteration in the material. Reviewed literature covers all information based on dissimilar

welds between the two materials. It shows that little research has been complete when

considering the eight key points, leaving a large gap in understanding. The methodology

covers the welding process, reasons for applying argon, atmospheric and phase changing

material (PCM) based heat treatments, procedures followed for conducting tensile stress and

Vickers hardness tests. The amount and type of optical microscopy, SEM and EDX

techniques utilised are also considered. The tests produced results on the ultimate tensile

strength, hardness, changes in the grain boundaries, level of material loss and elemental

presence. Each result was compared to literature and showed the presence of trends in both

the hardness and tensile stress. From these comparisons the main results determined are that

the bulk material and welded material appear to have very similar tensile strength and

hardness but differ in ductility and stiffness.

Keywords: Dissimilar welds, Stainless steel 316L, Inconel 625, Thermal treatments, Chemical treatments, Mechanical testing

Subject: Engineering thesis

Thesis type: Masters
Completed: 2023
School: College of Science and Engineering
Supervisor: Reza Hashemi