Finite element analysis of heat transfer in the MIG welding of type 304 staninless steel

It is known that heat transfer in weld pool, thermal waving and heated zone in the zone, which is affected by melting, affect the macro and micro structures. That phenomenon effects on the mechanical properties of materials. These effects can only be examined by experimental studies. However, industrial applications may not make possible to examine of these effects in every case. In this study, 304 type stainless steel was welded in four different welding speeds by MIG welding, and effects of heat on macro and micro structures and hardness were examined. 3D simulations in accordance with the experimental procedure by using ANSYS software were made and the results were compared.Temperature measurements of weld metal were taken from 10 different points by using infrared temperature measurement probe. The temperatures of base metal were measured by using K type thermocouples. The firs measurement, which was taken just after the first arc, showed that the temperature of the other end point of welding line, which is in 100 mm distance, was not increased. Once the weld reached on to the other end point, the starting point of weld line decreased dramatically to the lower temperatures. For this reason, the temperature distribution analysis of the weld line was carried out by dividing the whole weld line into the 10 equal sections for the ANSYS software. The arc point was determined as to be 2200 oC, which was measured by laser method, and then the section was left for cooling from this temperature. To analysis the every section, the result of the previously welded section was taken as the starting values.As it is known, the thermal properties of materials vary with temperatures. For this reason, the properties of 304 stainless steels were introduced to the ANSYS software depending on temperature. Energy changes between interval of melting and solidification temperatures were also introduced.To see the thermal stresses during the welding, structural analyses made in the ANSYS software using results of temperature obtain as experimental.When the experimental and modeling results were compared, they were found as similar. To get a similar result from ANSYS analysis depends on the introducing of material properties and boundary conditions very well.