9 research outputs found
Effect of Strain Rate on the Martensitic Transformation During Plastic Deformation of an Austenitic Stainless Steel
Effect of Strain Rate on the Formation of Strain-Induced Martensite in AISI 304L Stainless Steel
Three-Dimensional Thermomechanical Simulation and Experimental Validation on Failure of Dissimilar Material Welds
Dissimilar material weld joints, consisting of low-alloy steel and 304LN austenitic stainless steel
(SS), have critical application in boiling water reactors in the nuclear industry. It was predicted
that phase transformation adjacent to the fusion boundary and stress distribution across the
transition joint play a key role in the structural degeneration of these welds. Quantitatively, to
evaluate their contribution, two different joints were considered. One was fabricated with
buttering material 309L SS (M/S Mishra Dhatu Nigam Limited, Hyderabad, India), and the
other was produced with buttering material IN182 (M/S Mishra Dhatu Nigam Limited,
Hyderabad, India). Base materials remained the same for both. Thermomechanical simulation
on dissimilar material welds was performed using finite-element modeling to predict the thermal
effect and stress prone area. Temperature-dependent thermal and structural properties were
considered for simulation. Simulation results were compared with microstructural characteristics,
and data were obtained from the in-situ tensile test. Simulation results exhibited that stress
was at maximum in the buttering material and made the zone weaker with respect to adjacent
areas. During the validation of results, it was observed that failure occurred through buttering
material and endorsed the inference. The variation in mechanical properties of the two welds
was explained considering the effect of thermal state and stress distribution
Experimental and Computational Investigation of Structural Integrity of Dissimilar Metal Weld Between Ferritic and Austenitic Steel
The structural integrity of dissimilar metal welded (DMW) joint consisting of low-alloy steel
and 304LN austenitic stainless steel was examined by evaluating mechanical properties and
metallurgical characteristics. INCONEL 82 and 182 were used as buttering and filler materials,
respectively. Experimental findings were substantiated through thermomechanical simulation of
the weld. During simulation, the effect of thermal state and stress distribution was pondered
based on the real-time nuclear power plant environment. The simulation results were co-related
with mechanical and microstructural characteristics. Material properties were varied significantly
at different fusion boundaries across the weld line and associated with complex
microstructure. During in-situ deformation testing in a scanning electron microscope, failure
occurred through the buttering material. This indicated that microstructure and material
properties synergistically contributed to altering the strength of DMW joints. Simulation results
also depicted that the stress was maximum within the buttering material and made its weakest
zone across the welded joint during service exposure. Various factors for the failure of dissimilar
metal weld were analyzed. It was found that the use of IN 82 alloy as the buttering material
provided a significant improvement in the joint strength and became a promising material for
the fabrication of DMW joint