Received 23 May 2015 Accepted 15 August 2015 Available online 30 September 2015 In the present paper, the effects of friction stir welding (FSW) tool rotational and traverse speeds on heat generation and temperature distribution in welding zone of AA1100 aluminum alloy and A441 AISI joint were studied. Computational fluid dynamics method was used to simulate the process with commercial CFD Fluent 6.4 package. To enhance the accuracy of simulation in this study, the welding line in the work-pieces interface was defined with pseudo melt behavior around the FSW pin tool. Simulation results showed that with increase of the FSW tool rotational speed, more heat was generated heat and the dimensions of the stir zone were enlarged. The calculation results showed that maximum temperature occurred on the advancing side. Moreover, with increasing tool linear speeds the heat generation experienced a downward growth trend. With increasing the traveling speeds the time to reach maximum temperature in the stir zone increased, but the tool rotational speed had no effect on the time to reach maximum temperature. The model outcomes showed that more than 85% of total heat was produced by tool shoulder and that the maximum heat with the selected parameters was 935 kelvin degrees. The computed results showed that the maximum value of strain rate achieved was 29 S-1 for the A441 AISI and 42 S-1 at the AA1100 side.