Improvement of toughness and strength of thick structural steel weld by friction stir welding conditions

Abstract

Structural steel plates with tensile strength of 490 MPa and 6 mm in thickness were successfully joined with microstructural control by single sided one-pass butt friction stir welding (FSW). The microstructure in the stir zone (SZ) could be changed to bainite, bainite with proeutectoid ferrite, and fine equiaxed ferrite based on the welding temperature. The bainite increased the hardness and tensile strength, and the ferrite gave the joint similar mechanical properties similar to the base metal. The welding temperature was controlled between below Ac 1 and above Ac 3 by the rotating rate of the tool and tool materials; i.e. Ir-Re alloy and sintered c-BN with W-Re.

The microstructure and wear behaviour of friction stir processed AISI 430 ferritic stainless steel

“…Generally, the grain growth at high temperature worsens the mechanical properties of the fusion welds of ferritic stainless steels [41]. However, the significant grain refinement is one of the main advantages of FSW/FSP, resulting in the improvement of tensile strength [42, 43].…”

Fabrication of thick multilayered steel structure using A516 Grade 70 by multipass friction stir welding

“…With the development of advanced tool materials, 1 friction stir welding (FSW), a revolutionary solid-state joining process, has been effectively applied to various highstrength steels. [2][3][4][5][6][7][8][9][10][11] This is because steels are widely used for many structural applications. Overall, researchers found improved mechanical properties in the SZ due to a refined grain size by controlling the FSW parameters.…”