COMBINED FINITE ELEMENT MODELING OF WAVE DEFORMATION HARDENING OF WELDS

The study objective is to develop and verify a combined finite element model for evaluating the effect of wave deformation hardening (WDH) on the stress-strain state and hardness of welds. The task to which the paper is devoted is to make a combined ANSYS model that takes into account the stages of forming a welded joint and the subsequent dynamic impact of the tool, as well as the development of a method to convert modeling results into hardness values. The simulation is performed using the finite element method in ANSYS Workbench using Transient Thermal, Static Structural and Transient Structural modules. Experimental verification is carried out on samples made of 15X2NMFA steel with a weld made of sv-09KHGNMTA-VI wire at impact energies of 150 J, overlap coefficients K=0.2; 0.4; 0.6 and temperatures of 20°C and 200°C. The scientific novelty is the development of a combined finite element model, which for makes it possible the first time in a single cycle to predict the formation of residual stresses during welding and their change under WDH action, as well as to find out empirical dependencies for converting plastic deformations into hardness, taking into account the overlap and temperature factors. The verification of the model showed high convergence with the experiment - the error in determining the size of the print is less than 3%, the average error in predicting hardness is no more than 4.5%. It is found out that the optimal WDH mode is treatment with K=0.6 at 200°C, which provides a significant increase in compressive residual stresses in the weld and the zone of thermal influence, as well as an increase in surface hardness to 259 HB, which is 12.5% higher than the initial value (228 HB). The developed model adequately describes WDH process and can be used to optimize the technological modes of hardening welded joints of critical structures of transport engineering.