Soldagem do aço ABNT 4140 sem tratamento térmico posterior

Abstract

The welding procedure of the conventional steel AISI 4140 due to the formation of martensite in the heat affected zone by heat (HAZ), comprises a post-welding heat treatment to relieve stresses and improve the toughness of this zone. This thermal treatment often becomes impractical due to factors such as part size, and field repair cost. The technique of double-layer has been studied in order to avoid this thermal treatment and to ensure good mechanical properties of the welded part. The use of the technique of double-layer requires an appropriate relationship between the energy of welding of the layers, so that the second and refines the HAZ revina coarseness of the first, since in this region the possibility of formation of martensite is large because of its higher hardenability . In this work, we used a preliminary test called Higuchi allowing the choice of energy. Then welds were carried out in simple deposit and single layer in specimens quenched and tempered in order to assess the degree of refining and tempering provided by lateral passes. After this test, the specimens were welded and tempered using the double-layer and then through metallography and microhardness testing, evaluate the degree of refining and tempering porporcionados to use the technique of double layer. The welding together of a semi-V allowed the evaluation of the toughness of HAZ of the first layer by conducting the Charpy test. The results of this test showed that the energy absorbed by welded specimens, with the relations of welding energy (KJ / cm) of the first and second layer of 5/5 and 5/10, are similar to those of specimens with post-weld heat treatment and superior to the base metal and tempered resold, demonstrating the feasibility of the technique.