Journal of Applied Mechanical Engineering

Estimation of residual stresses in an 800 mm thick narrow-gap steel weldment

International Conference on Design and Production Engineering

July 25-26, 2016 Berlin,Germany

N Siva Prasad

Gitam University, India

Scientific Tracks Abstracts: J Appl Mech Eng

Abstract:

An 800 mm thick narrow-gap carbon-manganese steel weldment was fabricated using the submerged arc welding process. A total of 600 weld beads were deposited to butt weld 800 mm thick plate of 1.5 m length. Residual stresses in the weldment were determined by finite element analysis in the multi-pass welding, assuming plane strain conditions. The addition of filler material was simulated using the dummy material method. Solid-state phase transformations were also taken into account. The welding heat source was simulated using Goldak�??s double ellipsoidal model. The heat source was calibrated using the welding parameters and macrograph of the weldment. A bead-by-bead deposition model and two different lumped models were used for analysis. The results obtained by these models were validated by experimental measurements. While both bead-by-bead and lumped models were found to overestimate the maximum residual stress in as-welded condition, the latter facilitated a safer upper-bound estimate of the residual stress. Moreover, the computational time required for lumped model was about 10% of that required by the bead-by-bead deposition model. The net tensile stress in the weld metal was found to decrease as a result of solid-state transformation of austenite to ferrite. The effects of post-weld heat treatment at 600°C were also studied. The steady-state creep during post-weld heat treatment was simulated using Norton�??s law. A significant part of stress relief was found to occur in the first half hour of the holding time during post-weld heat treatment. A formula was developed for estimating the maximum residual stress in post-weld heat treated condition. The relative influence of temperature and time of post-weld heat treatment on stress relief was studied.

Biography :

N Siva Prasad has completed his PhD from IIT Madras. He has published more than 75 papers in reputed journals and has been serving as a reviewer for many journals. His research interests are Finite Element Analysis, and Computer Aided Design.

Email: sivacae@yahoo.com