Recent advances in friction-stir welding : Process, weldment structure and properties

Friction stir welding/processing of metals and alloys: A comprehensive review on microstructural evolution

Analysis of process parameters effects on friction stir welding of dissimilar aluminum alloy to advanced high strength steel

Effect of welding processes and conditions on the microstructure, mechanical properties and corrosion resistance of duplex stainless steel weldments—A review

Overview of friction stir welding and examples of adoptions highlights and issues- Fundamentals of the friction stir process process parameters, material flow and microstructural evolution, tool features and role- Modeling and simulation of microstructural evolution during FSW/P- Friction stir welding configurations and tool selection gaps and mismatches- FSW of aluminum alloys low strength alloys, tailor welded blanks and tool/process design to maximize productivity, high strength alloys and strategies to maximize joint efficiency- FSW of magnesium alloys- FSW of high temperature alloys issues with tool materials and examples of titanium alloys and steels- Friction stir processing overview of derivative processes and potential- Residual stresses and mitigation strategies

Friction Stir Welding and Processing : Science and Engineering

Five types of ferrite–pearlite structure carbon steels with different carbon contents (IF steel, S12C, S20C, S35C, S50C) were friction stir welded under various welding conditions, and the mechanical properties and microstructures of the FSW carbon steel joints were evaluated. Compared with IF steel, the microstructures and mechanical properties of the carbon steel joints are significantly affected by the welding conditions. When the carbon content is less than or equal to 0.12 mass%, the welding produces ferrite–pearlite structures, and the strength slightly increases compared to the base metal due to the refined microstructure; when the carbon content is above 0.2 mass%, the welding produces ferrite–pearlite plus harder phases like the martensite and bainite microstructures, resulting in a significantly increased strength of the joints. These are dependent on each of the thermal-mechanical cycles.

Transformation in Stir Zone of Friction Stir Welded Carbon Steels with Different Carbon Contents

For friction stir welding (FSW) of advanced high strength steel (AHSS) sheets with tensile strength grades between 590 and 1180 N mm−2, the appropriate welding condition range and the influence of welding conditions on microstructures and mechanical properties of the welds were investigated. The appropriate welding conditions to avoid defects such as the incomplete consolidation at the bottom of the weld were obtained for the steel sheets up to 1180 N mm−2 grade. The higher tool rotation speed evidently resulted in the larger volume fraction of martensite and higher hardness in the stir zone (SZ), attributed to an increase in the peak temperature of its thermal cycle. The tensile strength of the weld joint was as high as that of the base metal for the steels up to 980 N mm−2 grade, but slightly lower than that of the base metal for the steel of 1180 N mm−2 grade due to the heat affected zone (HAZ) softening.

Development of friction stir welding of high strength steel sheet

This indirect spot welding is for welding members including at least two overlapping steel sheets that have a ferrite phase as a main phase by holding a welding electrode (23) against a steel sheet (21) from one side while applying pressure with the electrode (23), attaching a feeding point (24) to a steel sheet (22) at the other side at a location remote from the electrode (23), and allowing current to flow between the electrode (23) and the feeding point (24). This welding includes contacting magnetic rigid bodies (26-1, 26-2) to a peripheral area of the electrode (23) from the one side against which the electrode (23) is held and securing an overlapping region in the peripheral area of the electrode (23) by a magnetic force produced by the rigid bodies (26-1, 26-2), thereby obtaining a weld having fully satisfactory strength, regardless of the rigidity of the members.

Indirect spot welding method

Material flow is a key phenomenon to obtain sound joints by friction stir welding (FSW), and it is highly dependent of the welded material. It is well known that the optimal FSW condition depends on the welded material. However, the material flow during FSW has not been totally clarified in spite of many researches. Especially, the material flow of steel during FSW is still unclear. It seems difficult to understand the material flow by the traditional method such as the tracer method or observation of the microstructure in the stir zone. Therefore, in this study, the material flow of steel was three dimensionally visualized by x-ray radiography using two pairs of x-ray transmission real-time imaging systems, and was then compared with the material flow of aluminum. The result revealed the effect of the welded material on the material flow during FSW.

Muneo Matsushita

Papers

Transformation in Stir Zone of Friction Stir Welded Carbon Steels with Different Carbon Contents

Development of friction stir welding of high strength steel sheet

Indirect spot welding method

Three-Dimensional Visualization of Material Flow During Friction Stir Welding of Steel and Aluminum

Microstructure and Toughness of Friction Stir Weld of Thick Structural Steel