Effect of surface roughness on weldability in aluminium sheets joined by cold pressure welding

• Published in: Industrial lubrication and tribology Vol. 60; no. 5; pp. 249 - 254
• Main Author: Sahin, Mumin
• Format: Journal Article
• Language: English
• Published: Bradford Emerald Group Publishing Limited 15.08.2008; Emerald
• Subjects: Applied sciences; Cold; Cold welding; Copper; Deformation; Exact sciences and technology; Experiments; Fracture mechanics (crack, fatigue, damage...); Friction welding; Fundamental areas of phenomenology (including applications); Inelasticity (thermoplasticity, viscoplasticity...); Interfacial bonding; Investigations; Joining, thermal cutting: metallurgical aspects; Metals; Metals. Metallurgy; Physics; Solid mechanics; Structural and continuum mechanics; Studies; Tensile strength; Welding; Welding; Cold welding; Tensile strength; Cold pressure welding; Surface layer; Roughness; Metal; Rough surface; Hardness; Contact surface; Weld; Tensile stress; Inelasticity; Welded joint; Fatigue strength; Plasticity; Surface deformation; Breakdown; Surface pressure; Ductile material; Metal foil; Microstructure; Weldability
• ISSN: 0036-8792; 1758-5775
• DOI: 10.1108/00368790810895187

Purpose - The purpose of this paper is to examine the effects of the welding deformation and surface roughness in cold pressure welding on the tensile strength and the fatigue strength of joined sheets. Additionally, the paper seeks to analyse the hardness variations and microstructures at the welding interface.Design methodology approach - Cold pressure welding is a method of joining similar or dissimilar ductile metals. It can be applied by bringing into close contact the surfaces of virgin metal specimens that appear due to the breakdown of the surface layers caused by bulk plastic deformation. Cold pressure welding is applied to test parts without too long a delay after the preparation of surfaces. The application of welding in 10 min affects importantly the weld strength. As this time is increased, the weld strength of the joints is decreased. The determination of deformation amount is found by determination of the reduction (R) at the total thickness of the two parts after the welding process.Findings - The weld strength increases as the surface roughness and weld deformation of the joined sheets increase. The length of bond zones increases with increasing deformation. Therefore, the weld strength of parts depends on the length of bond zones. Then, there is an effect of surface roughness on the welding strength. Joined sheets show resistance to little fluctuating tensile stress. It is observed that the parts rupture from the welding-interface hardness values are about the same at interfaces of sheets having different surface roughness and equal deformation (60 per cent). But, if it is considered that hardness of aluminium material purchased is about 53 HV, it can be said that the hardness increases in joined parts because of local hardening during deformation in cold pressure welding method as lap welding. Bond formation at interfaces of joined sheets having Ra=5 μm surface roughness and deformation ratio 60 per cent is shown to be successful in the microstructure photo.Research limitations implications - Surface roughness and deformation values can be increased in further studies.Originality value - The paper offers insight into the effects of surface roughness on weldability.