This paper presents a new two-pass friction stir welding (FSW) implementation called parallel friction stir welding (P-FSW). This process is classified into two categories: Advanced parallel friction stir welding (AP-FSW) and retreating parallel friction stir welding (RP-FSW). The effects of three parameters named the type of process, tool offset in first pass, and tool offset in the second pass on tensile strength of AA6061-T6 and AA7075-T6 joint in FSW have been investigated experimentally. To design experiments, optimization, and analyzing the results, response surface methodology (RSM) has been used. Quantitative and qualitative variables have been considered in five and two levels, respectively. Based on obtained results, it has been observed that tool offset in the second pass, type of process, and tool offset in the first pass have the most effect on tensile strength of welded joint, respectively. In both AP-FSW and RP-FSW processes, the maximum tensile strength occurred at the maximum value of tool offset in the second pass and minimum value of tool offset in the first pass. The maximum joint efficiency of AP-FSW and RP-FSW processes with respect to AA6061-T6 were obtained 83.1% and 95.4%, respectively.

本文提出了一种新的两遍摩擦搅拌焊接（FSW）实施方式，称为平行摩擦搅拌焊接（P-FSW）。此过程分为两类：高级平行摩擦搅拌焊（AP-FSW）和后退平行摩擦搅拌焊（RP-FSW）。实验研究了三个参数，即加工类型，第一道次刀具偏移和第二道次刀具偏移对FSW的AA6061-T6和AA7075-T6接头抗拉强度的影响。为了设计实验，优化和分析结果，已使用响应面方法（RSM）。在五个和两个级别分别考虑了定量和定性变量。根据获得的结果，已经观察到第二遍的刀具偏移，过程类型，第一次焊接时的刀具偏移和刀具偏置分别对焊接接头的拉伸强度影响最大。在AP-FSW和RP-FSW过程中，最大抗拉强度都出现在第二遍的刀具偏移最大值和第一遍的刀具偏移最小值处。相对于AA6061-T6，AP-FSW和RP-FSW工艺的最大联合效率分别为83.1％和95.4％。