PENGARUH REPAIR LAS GMAW TERHADAP KEKUATAN TARIK, KEKERASAN, DAN STRUKTUR MIKRO PADA MATERIAL BAJA A36

Abstract

Welding is a technique of joining metal materials that has a detrimental impact in the form of defects in the material, especially welded joints, in the weld joint area with improper welding procedures resulting in weld defects in the material, changes in the crystal structure and mechanical properties of material. This research method is carried out by re-welding or repairing the defective material. The purpose of this study is to analyze and compare the mechanical properties of repair results with welded joints without repair. The repair process uses a variety of repair 2 times, repair 3 times, and repair 4 times by welding GMAW on A36 steel material. The results of the study were mechanical properties of the material in the form of the crystal structure of the specimen, the value of the hardness test and the ultimate tensile strength, microstructure testing there is a crystal structure of perlite and ferrite. The highest hardness test value is repair 2 times 170 HV, without repair 166 HV, repair 3 times 163.3 HV, and repair 4 times 162.8 HV on weld metal. The result of ultimate strength variation without repair 485 N/mm², repair 2 times 466.5 N/mm², repair 3 times 466.5 N/mm², repair 4 times 468 N/mm² with tensile test fracture located in the base metal area, the result of ultimate tensile strength repair 2 times, repair 3 times, repair 4 times is still within the minimum tensile provision of ASTM A36 steel material of 452 N/mm² so that welded joints that are made up to 4 times repair can be used.