Choice of Welding Energies for Application in Double Welding Technique in Welding of Steel ASTM 131 Grade AH 36

Abstract

During the welding process ASTM A131 Grade AH36 microalloyed steel may exhibit thermal cycling defects (distortions) that will require costly procedures such as post-weld heat treatment. In addition, this steel is not indicated to undergo normalization, normalization followed by tempering, or quenching and tempering. In this case, the double layer technique, which is based on the controlled deposition of the first and second layer passes through the appropriate choice of the welding energies ratio, appears as an alternative. In view of this, this work had as objective to find the relation of welding energy that satisfies the criteria of microhardness and macrography. For this purpose, preliminary welds were carried out for each energy and after that the verification with the welding of double layer in flat plate. The results indicated that the welding energy ratios 5/14 and 5/17 kJ.cm^-1 were approved, but the energy of 5/14 kJ.cm^-1 was the one that presented the greatest distance in the criterion based on microhardness. The double layer welding showed that the found energy ratio was adequate, presenting microhardness values ​​lower than the limit for the hardened zone (300 HV0,1), demonstrating the possibility of tempering by the overlapping of passes.

Key-words:
Welding; Double layer; ASTM 131 grade AH36