The Cooling Rate and Residual Stresses in an AISI 310 Laser Weld: A Meso-Scale Approach

Abstract

A three-dimensional coupled temperature-displacement finite element model was developed to generate values of temperature distribution, cooling rate, and residual stresses at the meso-scale level in a thick sheet AISI 310 laser welding test sample. High cooling rates (cooling time from liquid-to-solid temperatures) ranging from 960 °C/s to 2400 °C/s were observed when the calculations were made at the meso-scale level. These high cooling rates that arise during the formation of the weld pool originate the highest observed residual stresses that evolve throughout the weld during the entire heating and cooling cycles. An ABAQUS CAE meso model with dimensions of 10 × 5 × 1 mm (element size 100 µ) constructed from a global macro model of 40 × 10 × 75 mm (element size 1 mm) via the submodeling technique is presented in the present paper. In both analyses, macro and meso, the C3D8T thermally coupled brick, trilinear displacement and temperature elements were used. To mesh the entire plate with elements of regular size 100 × 100 × 100 µ, a total of 30 million elements are necessary. With the present approach, 1 macro mesh of 30 thousand elements (1 × 1 × 1 mm) and a meso mesh of 50 thousand elements (100 × 100 × 100 µ) were enough to simulate the weld problem at the meso-scale level.

Keywords

• laser weld
• heat input
• cooling rate
• residual stresses
• fusion zone
• meso scale