Interface strength investigations of 304 stainless steel/T2 red copper T-type brazed joint based on cohesive zone model

Abstract

Gas wave refrigerators are a type of refrigeration equipment with broad application prospects. The oscillating tube, its core component, was manufactured by brazing to improve production efficiency. To study the brazing interface strength, a small 304 stainless steel/T2 red copper T-type brazed joint specimen was designed. The tensile process of the brazed joint was simulated using ABAQUS software based on the bilinear cohesive zone model (CZM), and the results were compared with the experimental tensile results. Damage critical stress and critical fracture energy of ${\sigma }_{{\rm{\max }}}$ = 40MPa and ${\varphi }_{c}$ = 35 mJ mm ^−2 , respectively, were obtained. A VUMAT subroutine was used to obtain the fatigue life of the specimen, and the errors with the experiment were 1.8% and 5.6%, respectively. It was proved that the CZM can simulate the tensile and fatigue loading processes of T-type brazed joints. The microstructure of the fatigue fracture of the specimen was analyzed using scanning electron microscopy. In addition, the effects of cyclic displacement and base metal thickness on the interface fatigue damage process were simulated and analyzed. The results showed that with an increase in cyclic displacement, the crack initiation life decreased and the crack growth rate increased; the interface damage, the crack length, and the fatigue load increased with the increase in base metal thickness.

Keywords

• T-type brazed joint
• VUMAT subroutine
• cohesive zone model
• finite element simulation
• mechanical test