Development of friction stir welding of high strength steel sheet

Abstract

For friction stir welding (FSW) of advanced high strength steel (AHSS) sheets with tensile strength grades between 590 and 1180 N mm 22 , 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 22 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 22 grade, but slightly lower than that of the base metal for the steel of 1180 N mm 22 grade due to the heat affected zone (HAZ) softening.

Microstructural evolution during friction stir welding of dissimilar aluminum alloy to advanced high-strength steel

“…Larger tool offset means larger portion of the tool pin submerged in aluminum. Considering the severe frictional conditions associated with stirring steel, refractory materials such as tungsten carbide [20][21][22][23], tungsten-rhenium [24], Si 3 N 4 [25], and polycrystalline cubic boron nitride (PCBN) [26][27][28] are required as acceptable tool material candidates. In this study, tungsten carbide with a 10 % cobalt content was selected for its combination of good wear resistance and much lower cost compared with PCBN.…”

Development of Microstructure and Crystallographic Texture in a Double-Sided Friction Stir Welded Microalloyed Steel

“…Previous calculation, based on processing factors such as travel speed, tool rotation speed and torque [28] has shown that 20 rpm increase in tool rotational speed increases the heat input by 10%. Introducing high heat inputs with increased tool rotational rates during FSW and FSP of steels, resulted in higher temperatures and consequently, phase transformation [31][32].…”

The quantitative investigation of mechanical properties and characterization of fractured position for friction stir lap welded A6111/A5023

“…In the case of the FSW, revolutionary pitch (RP), which is the welding speed (V) divided by the rotation speed of the tool (N), V/N is used as a parameter for the heat input. The heat input is inversely proportional to RP [14,15]. Therefore, the relationship between peak load and revolutionary pitch was investigated as below.…”