Feasibility Study on Fabrication of Large-Scale Offshore Structural Steel Component Using LAAM Technology

Abstract

Abstract ASTM A131 Steel, grade EH36 is a high strength steel used extensively as structural parts in shipbuilding, Oil and Gas applications. In this work, additive manufacturing of a support node connecting the main platform and columns for semi-submersible offshore vessel was performed using Laser Aided Additive Manufacturing (LAAM) process to evaluate both technical feasibility and economic viability. Both coupon and component levels LAAM process study was carried out. Properties of printed EH36 steel are significantly determined by the printing process parameters. EH36 deposited with optimized LAAM process has shown better mechanical properties than conventional rolled EH36 material. A deposition strategy was developed to distribute the accumulated residual stress, to minimize substrate distortion and stress-induced cracking in the print part. A hybrid approach combining both substrate and AM, with a 60% print to hot-rolled substrate plate weight fraction was proposed to enable printability and to enhance efficiency. Near-net-shape node was printed without cracking/delamination using optimized printing strategy. Total printing weight is 70kg and total time spent is 90 hours. It was concluded that LAAM technology is feasible for fabrication of large load bearing structural steel sections.