Structural estimation of crack resistance of welded joints of high strength steels

• Date: 2014
• Main Author: Бердникова, Елена Николаевна
• Format: Article
• Language: Russian
• Published: Інститут енергетичних машин і систем ім. А. М. Підгорного Національної академії наук України 2014
• Subjects: welded joints; high-strength steel; structure; phase composition; destruction; crack resistance; УДК 621.791; 539.422
• Online Access: https://journals.uran.ua/jme/article/view/21320
• Journal Title: Energy Technologies & Resource Saving

The results of studies of structure and phase composition formation features of welded joints of high-strength steel14HGN2MDAFB with the yield strength σ0, 2 > 700MPa are given in the paper. Based on experimental data of optical scanning microscopy it was shown that the structure, formed in various zones of welded joints in terms of uniform change (without gradients) of structural parameters and microhardness should provide a uniform level of mechanical properties and crack resistance of welded joints.Using analytical estimates for hardening in the high-strength steel welding zone, hardening effect of the structure (grain, subgrain, particles of carbide phases), which is connected with the contribution of grain boundary, substructural and precipitation hardening due to dispersion of structural components was established.Computational estimation methods of crack-inducing stress in the zones of stress concentrators, based on experimental data of the quantitative fractographic analysis (with the account of  destruction type) showed that in structural volumes of intragranular cleavage microcrack-inducing stress is ~ 70 ... 120 MPa (at T=-40oC) that determines the catastrophic crack growth and crack resistance decrease, respectively.