Method of Welding Two Stainless Steel Plates

A method of friction stir welding two SUS301L-DLT stainless steel plates specified by JIS E 4049, wherein a side edge 3 of a plate 1 is aligned with the side edge 3' of a plate 1' and a pin 11, in a right-cylindrical shape formed at a front end of a rotary tool 10 in a rod shape, is inserted in between the respective side edges of the two plates 1, 1' such that the rotary tool 10 is rotated while being moved in the longitudinal direction, along the edges of the plates.. The pin 1 has no thread groove on the side face, i.e. is smooth or unthreaded, and the rotary tool 10 with the pin 11 contains Si3N4. The rotary tool 10 may also have a nozzle (16; fig 1b) which supplies argon gas to the tool and work piece For welding two SUS301L-DLT stainless steel plates of thickness 1.5mm, the rotary tool 10 has a shoulder diameter of 15mm and is rotated at 600rpm with a translational speed of between 180mm/min to 300mm/mm. The value of (the moving speed of the rotary tool [mm/mm] / the rotational speed of the rotary tool [rpm]) is in a range from 0.3 to 0.5, inclusive. The method provides a weld joint of equivalent strength to those achieved with conventional pins, but using a rotary tool as described improves the service life of the tool and reduces the cost of manufacture.