Significant cost and time savings may be realised if multiple weld repairs are undertaken at the same location during the long-term maintenance of naval vessels. Consequently, this investigation simulates full-thickness hull welds, which are required to facilitate the removal and subsequent replacement of hull sections, by assessing the effects of 4 reoccurring weld repairs on a propriety quenched and tempered steel used for naval applications. Optical metallography, electron backscattering diffraction (EBSD), hardness maps, Charpy impact, and dynamic tear tests were conducted. A combination of real weld repairs and Gleeble heat-affected zone (HAZ) simulations were undertaken to characterise the effects of repeated thermal cycles on the microstructure and toughness of different sub-HAZ regions. When the intercritical reheat temperature was just above the A_C1 lower critical transformation temperature, the impact toughness was substantially reduced. This includes the fine-grained HAZ where high toughness is typically expected. The low toughness was attributed to the promotion of fracture initiation via debonding between the matrix and second phase which formed at prior austenite grain boundaries. Compared to the original toughness, the application of multiple repeat welds or multiple simulations of the same sub-HAZ thermal cycle did not deteriorate toughness nor noticeably alter the final microstructure.

如果在海军舰艇的长期维护期间在同一位置进行多次焊接修复，则可以实现显着的成本和时间节省。因此，本研究通过评估 4 次重复焊接修复对用于海军应用的适当调质钢的影响来模拟全厚度船体焊缝，这是促进船体部分的移除和后续更换所必需的。进行了光学金相、电子背散射衍射 (EBSD)、硬度图、夏比冲击和动态撕裂测试。结合实际焊接修复和 Gleeble 热影响区 (HAZ) 模拟来表征重复热循环对不同子 HAZ 区域的微观结构和韧性的影响。_C1临界转变温度降低，冲击韧性大大降低。这包括通常需要高韧性的细晶粒 HAZ。低韧性归因于通过在原奥氏体晶界处形成的基体和第二相之间的脱粘促进了断裂的发生。与原始韧性相比，多次重复焊接或多次模拟同一亚热影响区热循环不会降低韧性，也不会显着改变最终的微观结构。