Friction stir welding (FSW) of 6-mm-thick plates of AA6061-T651 was carried out using a simple cylindrical pin tool. The impact of welding factors (rotational speed, welding speed) on tensile properties, microhardness, and surface roughness of FSW joints was investigated. Ultimate tensile strength (UTS), yield strength, and % elongation of AA6061-T651 base plate as well as FSW joints were found out using a universal testing machine (UTM). Maximum value of UTS and yield strength were achieved at rotational speed of 1400 rpm and welding speed of 20 mm/min. Minimum surface roughness was reached at rotational speeds of 1400 rpm and welding speed of 20 mm/min. Microstructural evolutions in the friction stir welded (FSWed) joint and microhardness profile were also determined. Maximum hardness of HV 120 was acquired for the stir zone (SZ). Hence, attainment of the maximum tensile strength, microhardness, and minimum surface roughness during FSW is a desired method to improve the service life and suitability of AA6061-T651.

中文翻译：

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搅拌摩擦焊AA6061-T651的力学性能和表面粗糙度的研究

使用简单的圆柱销工具对AA6061-T651的6毫米厚板进行搅拌摩擦焊（FSW）。研究了焊接因素（转速，焊接速度）对FSW接头的拉伸性能，显微硬度和表面粗糙度的影响。使用通用测试机（UTM）找出AA6061-T651基板以及FSW接头的极限拉伸强度（UTS），屈服强度和伸长率％。在1400 rpm的转速和20 mm / min的焊接速度下可以达到UTS的最大值和屈服强度。在1400 rpm的转速和20 mm / min的焊接速度下达到最小表面粗糙度。还确定了搅拌摩擦焊接（FSWed）接头的显微组织演变和显微硬度分布。搅拌区（SZ）的最大硬度为HV 120。因此，