Effect of microstructure in 304L stainless steel welding process
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Date
2016-06
Authors
Muhammad Hafiedz Mohamed Karbul
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Abstract
This research is done to investigate the effect of welding current and filler diameter of tungsten inert gas (TIG) welding on the mechanical properties and microstructural properties. Filler diameters that used in this study were 1.6mm and 2.4mm. The filler type is 308 fillers. Meanwhile, the welding current is 10A, 20A, and 30A. XRF results show the chemical composition of 304L stainless steel were within standard ranges. There are several tests that been conducted such as dye penetration test, tensile test, flexural test, and micro hardness test for mechanical properties, while for the microstructure analysis optical microscope (OM) and scanning electron microscope (SEM) were conducted. The joining was analysed by dye penetration test where filler 2.4 mm with 20A current supply were the lowest percent of the defect that is 7.0%. While for 1.6mm filler diameter the lowest percentage of a defect is from 30A current supplied that around 5.11%. The tensile strength of butt joined of filler 2.4mm diameter with tensile strength in the range 624 MPa to 640 MPa is better than joined of filler 1.6mm diameter with the tensile strength 613 MPa to 625 MPa. For 2.4mm filler diameter the highest tensile strength is around 639.7 MPa with 20A current supplied. For the flexural strength, the 3-point bending test was conducted. From this test 2.4mm filler diameter have better flexural strength with 848 MPa to 918 MPa compared to the 1.6mm filler diameter with 799 MPa to 906 MPa. For the micro hardness, 2.4mm have higher micro hardness value that around 323 HV to 355 HV. The highest value for the micro hardness is from the weld zone which there more ferritic structure. From the microstructure analysis, SEM and OM were conducted to know the element and the phase present inside the welded part and to analyse the heat affected zone (HAZ). Austenite and ferrite phase were found during the analysis.