Influence of Structure of Welded Connections from a Heat Resistant Steel on their Reliability

Abstract

Welded connections of steels 08Х25Т and 20Х23Н18 GOST 5632-72 (X8CrTi25 and X20CrNi23-18 under the standard EN100027-1 and CR 10260) were investigated. The welding was conducted by a manual way (111 LST EN 24063) using constant current of return polarity and covered electrodes. The main difficulty at welding of high-alloy heat-resistant steel is large deformations also an opportunity of a formation of cracks in a seam and adjacent to it zone. The formation of cracks can be caused by defects of welded seam, presence of hardened structure in a welded zone, saturation of metal of a seam by hydrogen, and internal stresses due to shrinkage of a metal of the seam. It is established, that the least reliability of welded seams is observed in the case of martensitic structure of a seam, and the greatest – in the case of an austenitic structure.