Friction welding is now well established as one of the most economical and highly productive methods in joining similar and dissimilar metals. It is widely used in automotive and aerospace industrial applications. Friction welding is often the only viable alternative in this field to overcome the difficulties encountered in joining the materials with widely varying physical characteristics. This process employs a machine that is designed to convert mechanical energy into heat at the joint to weld using relative movement between workpieces, without the use of electrical energy or heat from other sources. This review deals with the fundamental understanding of the process. The focus is on the mechanism of friction welding, types of relative motions of the process, influence of parameters, heat generation in the process, understanding the deformation, microstructure and the properties of similar and dissimilar welded materials.

Advances in friction welding process: a review

The present investigation attempts to understand the friction welding characteristics of sintered P/M steel preforms–wrought copper dissimilar parts. In order to achieve sound weld between these two materials the process parameters were optimized and inferred that the preforms of lower densities with lower process parameters yields quality weldments, established through post-weld tests. This study also envisages the influence of process parameters which include resident preform densities, friction pressure, upset pressure, and burn-off length on microstructure and mechanical properties of the welds. This work consolidates information on the aspects of joining P/M component with wrought materials for practical execution.

Investigations on the continuous drive friction welding of sintered powder metallurgical (P/M) steel and wrought copper parts

structural optimization, fatigue design, frames, platedstructures, residual welding stresses and distortions,static stresses in welded connections, hollow sections,welding technology, applications, applied mechanics.Authors are experts from 20 countries, ensuring awide spectrum and importance of the themes covered.The International Institute of Welding (IIW) andmany other sponsors helped organizers to collect thesevaluable studies, which provide an important referencefor civil and mechanical engineers, architects, design-ers and fabricators, as well as managers in a rangeof industries including building, transport, materialshandling, shipbuilding, aircraft, chemical and offshoreengineering.Most of the work relate to structural optimization,in which the structural safety and ﬁtness for productionare guaranteed by fulﬁlling the design and fabricationconstraints and the economy is achieved by minimiza-tion of a cost function. Welding technology and stressesarising from welded connections represent a signiﬁcantpart of the remaining papers. The book includes studieson structural analysis and design concerning fracture,instability, large deformations, fatigue, earthquake andﬁre loading.Papers can help the work of engineers, designers,producers, managers and researchers in designing andproducing competitive welded structures.

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Design, fabrication and economy of welded structures

The joining of copper to aluminum is inevitable for certain application in the electrical industry due to good conductivity and response offered by copper, aluminum for weight reduction. Whilst in the majority of cases, aluminum and copper can be joined by adhesive bonding, mechanical fastening, fusion welding and solid-phase welding techniques. Friction welding is well known for its ability to weld aluminum to many metals and consequently is being considered seriously. The present study describes about producing a sound joint between two dissimilar metals of pre-strained aluminum to commercially pure copper. Commercial pure aluminum is strained to reduce the disparity in strength level and the effect of pre-strain on friction welding is envisaged. The stronger metal (copper) in this combination is further weakened by intentionally removing some of the material so that a sound joint is obtained. Friction welding was carried out with pre-determined process parameters and the effect of initial geometry on friction welding is illustrated. Post weld characterization such as mechanical and microstructural studies of these welds was carried out to assess the quality of welds.

Influence of Rubbing Profile on Friction Welding of Pre-Strained Aluminum to Copper

In this study, the dissimilar friction welding of a medium C45 (AISI 1040) carbon steel and powder metallurgically produced tool steel 1.3344PM (AISI M3:2) (Vanadis 23) was investigated. Round bars of 11,3 mm diameter in hot-rolled and normalized condition were used. The welding experiments were carried out by an industrial friction welding machine with different friction welding parameters determined from pre-experimental studies and literature. Post weld heat treatment (PWHT) at 650 °C for 4 hours was also applied. Variations of microhardness were measured along the rod axis with 50g test load in all joints and the welding zones were examined with light optical microscope (LOM) and scanning electron microscope (SEM) including both as-welded and PWHTed samples.

Study of the Weld Zone of Friction Welded C45/1.3344PM Dissimilar Steel Joints

Continuous drive friction welding studies on sintered powder metallurgical (P/M) steel preforms–wrought mild steel combination are reported in the present study. The work is a preliminary study to optimise the friction welding parameters and data generated by the present work is expected to contribute to friction welding of dissimilar and similar sintered P/M preforms to wrought metals or sintered P/M preforms – a planned future research work. Sound welds were obtained with all welding parameter combinations studied. The mechanical properties of welds were comparable to those of sintered P/M steel. Sintered P/M preforms deformed to a greater extent than wrought mild steel due to their low flow stress and thermal conductivity. The sintered density and other properties of the P/M preforms were found to dictate the deformation at the interface and consequently the weld strength. The results indicate that the current approach can be extended to other combinations of sintered P/M preforms.

M. Ashfaq

Papers

Preliminary studies on friction welding of sintered P/M steel preforms to wrought mild steel