In this research, a study of the influence of arc welding parameters on the thermal cycle was conducted, where the thermal cycle within the welded plate of stainless steel 304L by plasma arc welding (PAW) with weld-on-plate was measured using thermocouples for several welding parameters (intensity of the welding current, welding velocity, flow rate of plasma gas) and comparing the influence of this parameters on the thermal cycle within the plate.