THE EFFECT OF VARIATIONS IN THE SHAPE OF THE SEAM ON MICROSTRUCTURE, HARDNESS AND TENSILE STRENGTH IN THE WELDING PROCESS OF STEEL SS400 WITH THE SMAW METHOD

Abstract

The purpose of this research is to investigate the influence of groove weld type on the welding joint to the physical and mechanical characteristic using the Shielded Metal Arc Welding (SMAW) method. The welding process causes the around metal has thermal cycles and then resulting metallurgical changes, deformations and thermal stresses. Because of these structural changes, the mechanical characteristic will change as well.

This research use experimental method that is researcher doing butt joint welding with X, V and ½ V groove weld type by using low carbon steel SS400 with carbon content 0,1% then testing micro structure, hardness and tensile strength.

Based on the results of the study, it can be concluded that the results of microstructure test showed improvement of acicular structure of ferrite and pearlite after welding. In raw material, the grain boundary structure of ferrite is evenly distributed. Hardness values on welding results indicate a different level of violence. The specimen with V type has the highest hardness of 248,6 VHN, then the specimen with ½ V form is 233,7 VHN and the specimen with the X type is 228,6 VHN while the raw material has hardness value 200,58 VHN. The value of tensile strength on the welding results indicates a difference. The specimen with the V type have the highest tensile strength level of 430,97 MPa and strain 18,11% then the ½ V type is 419,93 MPa and strain 15,52% followed by the X type with the average of tensile strength 414,88 MPa and strain 14,92% and on raw material has a tensile strength value 401,94 MPa and strain 13,26%. This study shows that welding using variations of groove weld type changes the microstructure and affects the hardness and tensile strength of SS400 Steel