Three-dimensional numerical simulation of brazed residual stress and its high-temperature redistribution for stainless steel plate-fin structure

A numerical simulated procedure is presented for analyzing the brazed residual stress and its high-temperature redistribution for stainless steel plate-fin structure applied to recuperative heat exchanger in gas-turbine power generation. Based on the finite element ABAQUS code, firstly, the as-brazed residual stress generated during cooling from brazing temperature to room temperature was obtained. Secondly, the residual stress redistribution due to creep relaxation behavior was simulated, which is implemented by Norton creep constitutive equation. Calculated results show that large residual stress with a complex distribution exists in the brazed joint. The peak stress is presented in the fillets where the crack would initiate and propagate. This is mainly caused by the mechanical properties mismatching between filler metal and base metal. But the as-brazed residual stress is greatly relieved and redistributed due to the creep relaxation at elevated temperature. The stress evolution regularity with time at 600 °C is achieved.