THE INFLUENCE OF THE TECHNOLOGICAL CYCLE OF PRODUCTION ON THE CHANGE IN THE PHYSICAL AND MECHANICAL CHARACTERISTICS OF BIMETAL WITH A BUTT WELDED JOINT IN THE CLADDING LAYER
The goal of the study is to consider the effect of explosion welding, heat treatment and cold straightening (gagging) in production of 09G2S + 08Kh13 bimetal with a butt welded joint in the cladding layer on the evolution of residual internal stresses. The impact of technological operations on the change in the level of residual stresses in a bimetallic material with a welded butt joint in the cladding layer was carried out using a non-destructive method of the magnetic memory of metals (MMM). This method is based on the use of the intrinsic stray magnetic field formed in the zones of increased dislocation density. The results revealed the special features of the location of zones with maximum values of the stress field gradient (dH/dx) and their evolution upon production of 09G2S + 08Kh13 bimetal with a butt welded joint in the cladding layer. An increase in the level of residual stresses in the cladding layer occurs after manual electric arc welding of 2 parts of the cladding layer made of 08Kh13 steel. It is shown that after explosion welding the level of residual stresses change. The stress relaxation occurs in the zone of weld in the cladding layer. At the same time, an increase in the level of residual stresses is observed in the main and cladding layer of the bimetal. To reduce the high level of residual stresses, we used the subsequent heat treatment of the obtained bimetallic samples in two different modes. The optimal heat treatment mode (heating to 720 ± 20°C, holding for 2 h, cooling with a furnace) which excluded the crack formation in the cladding layer upon mechanical straightening of bimetal was specified for 09G2S + 08Kh13 bimetal sample with a butt welded joint in the cladding layer.