Numerical and Experimental Study of Phase Transformations in Welding Processes / Badania Numeryczne I Doświadczalne Przemian Fazowych W Procesach Spawania

Abstract

The paper concerns the mathematical and numerical modeling of phase transformations in solid state occurring during welding. The analysis of the influence of heating rate, cooling rate and maximum temperatures of thermal cycles on the kinetics of phase transformations is presented. On the basis of literature data and experimental studies the evaluation of classic mathematical and numerical models of phase transformation is presented with respect to the advanced methods of welding by using a high speed and a high power heat source. The prediction of the structure composition in laser welded butt-joint made of S460 steel is performed, where phase transformations are calculated on the basis of modified numerical models. Temperature distributions are determined as well as the shape and size of fusion zone and heat affected zone (HAZ). Temperature field is obtained by the solution of transient heat transfer equation with convective term and external volumetric heat source taken into account. Latent heat of fusion, evaporation and heats generated during phase transformations in solid state are considered in the numerical algorithm due to the large temperature range present in analyzed process. Results of the numerical prediction of structure composition in HAZ are presented in this work. Obtained results of computer simulations are compared to experimental research performered on the laser welded joint.

Prediction of microstructure composition in steel plate heated using high power Yb:YAG laser radiation

“…Different structures occur in the heat affected zone (HAZ) as a result of different heating and cooling conditions. Changes in the microstructure covering phase transformations in solid state are the cause of significant changes in the mechanical and operational properties of this zone in comparison to base material [3].…”

“…Interpolation algorithms are used for the description of Yb :YAG laser beam heat source power distribution. Ordinary Kriging method [3,12] is used in the numerical algorithm, taking into account the real laser power distribution obtained in experimental research made on laser welding station equipped with TruDisk 12002 laser.…”