求翻译：试验过程中选取材料稳定的搅拌摩擦焊基础工艺参数（即搅拌头倾角、搅拌头旋转速度（主轴转速）、焊接速度）进行焊接试验，是什么意思？

Select materials in the process of testing stable basis during friction stir welding process parameter (that is, mixing head angle and head rotation velocity (speed), welding speeds) for welding test,