Experimental Study of Pin Profile Effects on Microstructure, Mechanical and Fatigue Properties of Friction Stir Welded AZ31B-H24 Magnesium Alloy Joints

Abstract:

Friction stir welding (FSW) has risen to prominence recently due to its ability to join alloys having low weldability such as magnesium alloys. This paper aims to enhance mechanical properties of FSW joints of AZ31B-H24 by varying pin profiles. In this work, four different tool pin profiles were investigated, namely cylindrical, conical, square, and triangular. The FSW processes were conducted at tool rotation speed of 1500 rpm and tool traveling speed 30 mm/min. Afterwards, several experimental works were conducted, i.e. microstructure observations, hardness measurements, tensile tests, and fatigue crack growth rate (FCGR) tests combined with scanning electron microscopy (SEM) fractographic study. Results showed that the square pins produced the best FSW joints with the ultimate tensile strength (UTS), typically of 212.3 MPa respectively. Fractographic analysis showed that the fracture occurred in weld nugget zone (WNZ) close to advancing side (AS). It seemed that the high strength of FSW joints produced by the square pin was likely attributed to the proper frictional heat and material flow which gave the best dynamic recrystallization in WNZ. The present investigation also revealed that FSW joint under the the square pin had better fatigue performance than AZ31B-H24 base metal as indicated by its lower FCGR.

• Periodical: Materials Science Forum (Volume 1195)
• Pages: 51-60
• DOI: https://doi.org/10.4028/p-O4LtFQ
• Online since: June 2026
• Authors: A.E. Rahmani*, M.N. Ilman
• Keywords: AZ31B-H24 Magnesium Alloy, Fatigue, FSW, Mechanical Properties, Tool Pin Profile

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