Investigation on the Weldability of Developed High-Strength Hull Structure Steel

The weldability of a developed high-strength hull structure steel is investigated using a coarse-grained heat-affected zone (CGHAZ) thermal simulation and duplex double welding under a heat input of approximate to 20 kJ cm-1. From the results, the average impact test energy at -50 degrees C for the simulated CGHAZ samples is 142 J and for samples with V-notch position 0.5 mm from the fusion line (FL) was 152 J. The impact test energies for the V-notch position at the FL also show good toughness. The simulated samples and samples from the weld joint are machined into standard sizes to test their tensile strengths, which meet the request high strength. It is concluded that the high strength of the CGHAZ is mainly due to phase transformation and is supplemented by solid solution strengthening. The good low-temperature toughness is mainly due to the high Ni content. All the results are comparable to the reported mechanical property test results of the weld joint of navy HSLA-100 steel under a similar heat input. This suggests that the developed high-strength hull structure steel exhibits satisfactory weldability.