KUALITAS REPAIR WELDING DENGAN METODE OKSI-ASETILIN DAN PERLAKUAN PREHEATING PADA CAST WHEEL ALUMUNIUM SEBAGAI SUPLEMEN MATERI MATA KULIAH TEKNIK PENGELASAN

The purposes of this research are: (1) To determine the chemical composition and aluminium alloy standard codification of cast wheel aluminium. (2)To determine the microstructure before and after welding with oxy - acetylene welding method with preheating on the cast aluminium wheel. (3) To determine the level of hardness, before and after welding with oxy-acetylene welding method with preheating on the cast wheel aluminium. (4) To determine the level of impact strength before and after welding with oxy - acetylene welding method with preheating on the cast wheel aluminium. (5)To add a teaching module of welding technique course with Oxy-Acetylene repair welding method and preheating treatment. The Object in this research used arealuminium castwheels. Techniques of data analysis in this research using descriptive data analysis that is directly observed experimental results and then analyzed and summing up the results of the research. As an input parameter in analyzing the data include:the testing of chemical composition, microstructure, hardness and impact. From the research, we can concluded that (1) The cast wheel is made of cast aluminium alloy type AA.4011 which has a characteristic non heat-treatable, medium resistant of strength and ductility, resistant to corrosion and has good characteristic of capable cast. (2) Microstructure on base metal granules, HAZ and the weld area on the material results of oxy-acetylene welding visible form of the element Si granules are scattered in different Al matrix. on the raw area, Si granules are smaller and spread equally on the surface of Al. on the weld area, Si granules are larger than raw area and spread equally on the surface of Al. on HAZ area Si is larger and does not spread equally on the surface of Al. Influence of the preheating treatment of the welds specimen make the cooling rate is more stable, so the microstructure of the raw, HAZ and weld are showed differences not significant. It is seen from the micro image in which the boundary area between the base metal, HAZ, and weld area is not clearly visible. (3) Specimen hardness value of raw material is higher thanoxy-acetylene welding specimens.The average value ofraw material hardness results 65,829BHN. The average value ofoxy-acetylene weldingresults 59,168 BHN. The average hardness oxy-acetylene welding specimens in the HAZ area 62,325BHN. (4) The average value ofraw material impact results 0,0686 J/mm² whilethe average value ofoxy-acetylene weldingresults0,0294 J/mm²