ANALISIS SIFAT MEKANIK dan STRUKTUR MIKRO PADUAN AL 5083 pada HASIL PENGELASAN METAL INERT GAS (MIG) AKIBAT VARIASI PREHEAT dan POST HEAT

Abstract

Aluminium is an element with the largest amount on earth with the specific weight only 2,7 g/cc. Aluminium have a lighter weight on the same strength comparing with iron. The purpose of this study is to analyze the influence of using different variation of preheat and post heat in MIG welding of aluminium 5083. Ideally a weldment, by this is meant the complete joint comprising the weld metal, heat affected zones (HAZ) and the adjacent parent metal – should have the same properties as the parent metal. There are, however, a number of problems associated with the welding of aluminium and its alloys that make it difficult to achieve this ideal. Once of solution for problems in welding of aluminium is to preheat and post heat the specimen. Preheating is done to prevent cracking of welds. Preheat is also sometimes used for reducing residual stress, improving toughness, and controlling the metallurgical properties of the heat affected zone (HAZ). Several heat treatments can be applied after welding. The most frequently used heat treatment after welding is for reliefing of residual welding stresses, reduce weld and HAZ hardness, Improve toughness, Outgas hydrogen from the weld and increase ductility. The specimen with preheat and post heat in this research has increased. Tensile strength with preheat and post heat is 146 Mpa, but no preheat or post heat produce 59 Mpa. Hardness of HAZ, fusion, first and second layer have decreased.