Friction stir welding (FSW) is a solid-state process, where a tool that consists of a shoulder and a pin rotates between the plates to be welded by plastic deformation. This process involves several physical phenomena. To better understand this complex phenomenon, simulations have been performed for a range of maximum viscosity values. The viscosity model used in friction stir welding simulations depends on two variables, the temperature and strain rate; however, the viscosity goes toward infinity for low values of temperature and strain rates. This study analyzed two different friction stir welding simulation, by observing how the viscosity functions behave for low values of temperature and strain rates. The maximum viscosity value was shown to be restricted to values, where the velocity field tends to zero. Furthermore, when the viscosity value exceeds the maximum value, the temperature and viscosity field is significantly impaired. In the correct results, the change in viscosity is restricted to stir zone.

搅拌摩擦焊（FSW）是一种固态过程，其中，由肩部和销钉组成的工具通过塑性变形在待焊接的板之间旋转。这个过程涉及几种物理现象。为了更好地理解这种复杂现象，已经对一系列最大粘度值进行了仿真。搅拌摩擦焊模拟中使用的粘度模型取决于两个变量，即温度和应变率；温度和应变率取决于温度。但是，对于较低的温度和应变率，粘度会达到无穷大。这项研究通过观察粘度函数在温度和应变率较低时的行为表现，分析了两种不同的搅拌摩擦焊模拟。最大粘度值显示为仅限于速度场趋于零的值。此外，当粘度值超过最大值时，温度和粘度场显着受损。在正确的结果中，粘度变化仅限于搅拌区。