Effects of Welding and rotational speeds on the Microstructure and Hardness of Friction Stir Welded Single-Phase Brass

doi:10.1007/s40195-015-0259-z

Abstract

Abstract:

This study focuses on the effects of rotational and welding speeds on the microstructure and hardness of joints in friction stir welded single-phase brass. Welds were achieved under low heat input conditions at rotational and welding speeds of 400-800 r/min and 100-300 mm/min, respectively. In order to characterize the obtained welds, optical microscopy and Vickers hardness measurements were taken on the weld cross sections. According to the obtained results, increasing the welding speed and/or decreasing the rotational speed caused the grain size of the stir zone to decrease and, hence, improved the average hardness of this region. These results are discussed with respect to the interplay between the welding parameters and the peak temperature in the weld thermal cycle.

Key words: Friction, stir, welding, Single-phase, brass, Dynamic, recrystallization, Hardness

Sajjad Emami, Tohid Saeid. Effects of Welding and rotational speeds on the Microstructure and Hardness of Friction Stir Welded Single-Phase Brass[J]. Acta Metallurgica Sinica (English Letters), 2015, 28(6): 766-771.

Figures/Tables 10

Fig. 1 a Friction stir welding setup; b schematic of the welding tool

Fig. 2 Process window of the defect free welds

Fig. 3 Weld surface appearances at different welding conditions

Fig. 4 Cross-sectional macrostructure of welds at different welding conditions

Fig. 5 Optical macrographs of brass after FSW (400 r/min, 100 mm/min): a overall 3D macrograph; b BM region, labeled by A; c TMAZ/SZ border in the advancing side, labeled by B; d SZ region, labeled by C; d SZ/TMAZ border in the retreating side of weld, labeled by D

Fig. 6 Variation in SZ microstructures at different welding conditions

Fig. 7 Microstructure variation in weld center from the top a to the bottom c of 400 r/min, 100 mm/min sample: a overall view of weld center; b top region, labeled by A; c middle region, labeled by B; d bottom region, labeled by C

Fig. 8 Hardness profiles in cross section of the weld

Fig. 9 Variation in hardness in the SZ for all welding conditions

Fig. 10 Variation in hardness with grain size in FSW of single-phase brass

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