The effects of heat treatment on the microstructure and microhardness of explosive welding

Abstract

An AISI 304 type of austenitic stainless steel and low carbon steel were cladded by explosive welding in this study. Four explosive loading rates were used with the range of 1 and 2.0. Stand-of distance (s=t) was also used as a welding parameter. Cladded materials have been subjected to heat treatment at 250°C for times of ranging from 1 to 4 h. Effect of heat treatment on the microstructure and mechanical properties has been evaluated using optical and scanning electron microscopy, EDS analysis technique and hardness tests, respectively. The results indicate that straight and wavy structures of bonding at the interface were obtained according to the loading of explosive rate. The grain size of the cladded materials near the interface were increased with the duration of heat treatment. Hardness values at the interface of the cladded materials were decreased with the increment of heat treatment period.

The influence of the post-weld heat treatment on the microstructure of Mangalloy – carbon steel clad-plate obtained by explosive welding

“…The important aspect of this process is a significant strain hardening in the bimetallic joint zone, which causes problems in the forming process of the clad-plate. For this reason, the clad-plate after explosive welding process is subjected to the heat treatment to reduce strain hardening and to eliminate the residual stress in the joint zone [11,12,15]. In this research, the investigated clad-plate consists of steel C45 (base material) and Mangalloy (cladding material).…”

“…The important aspect of the explosive welding technique is knowledge about microstructure changes in the joint line during heat treatment. Depending on the properties of welded materials, there is a possibility of new phase formation (including intermetallic compounds) due to diffusion changes in the joint subjected to annealing process [13,15]. Significant plastic deformation in the joint area also can drastically reduce the amount of energy needed for heat-activated phenomena in welded materials, e.g., precipitation processes, recrystallization [13,[18][19][20].…”

The Influence of the Post-Weld Heat Treatment on the Microstructure of Inconel 625/Carbon Steel Bimetal Joint Obtained by Explosive Welding

“…According to previous investigations performed by the authors of this paper, the normalizing of Inconel 625-steel P355NH joint obtained by explosive welding decreases its shear strength by 33% (decrease from 572 MPa to 383 MPa, determined according to PN-EN13445:2014) [22]. The heat treatment of the explosively welded clad-plate may result in such changes in the joint zone as grainy microstructure evolutions (recrystallization, grain growth), diffusion processes, as well as, the formation of new phases [16,21,[25][26][27][28]. The character of the diffusion zone depends on the mutual solubility of the alloy chemical components.…”

The Influence of the Post Weld Heat Treatment on the Microstructure of Inconel 625/Carbon Steel Bimetal Joint Obtained by Explosive Welding

“…The present paper aims to investigate the causes of such a drastic reduction in the strength of the joint. Structural changes may involve both evolution of the grainy structure of the materials and diffusion processes within the joint [16,21,[25][26][27][28]. Depending on the mutual solubility of the diffusing chemical elements of the alloy, brittle intermetallic compounds or new solid solutions may be formed in the joint area [29,30].…”