Abstract
Three high-strength Nb-, Ti- and Ti + V-microalloyed S690QL steels were welded to investigate the formation of softened HAZ and its impact on tensile properties. The welding was performed with three levels of heat input to produce softened zones with different characteristics (softening width, minimum hardness and softening ratio), and then, further tensile tests were done to study their influence on weld performance. The results showed that Ti bearing steel exhibited the lowest resistance to softening with the presence of largest soften width and lowest hardness value, causing final tensile failure occurred at softened HAZ. The metallurgical reason for the lower hardness is the high fraction of coarse ferrite. Nb- and Ti + V-bearing steels suffered moderate softening, due to high hardenability with addition of Mo, Nb and V, but the softening effect did not remarkably influence the tensile properties of these two steels.
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The authors thank R. S. Neumann, R. Haecker, D. Schroepfer and T. Michael from Federal Institute for Materials Research and Testing (Germany) for their kind support. One of the authors (Lei Zhang) also appreciates the funding support from China Scholarship Council.
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Zhang, L., Kannengiesser, T. HAZ softening in Nb-, Ti- and Ti + V-bearing quenched and tempered steel welds. Weld World 60, 177–184 (2016). https://doi.org/10.1007/s40194-016-0299-7
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DOI: https://doi.org/10.1007/s40194-016-0299-7