Abstract
Several low alloy structural steels with different levels of Ni, Cr, and Mo and carbon contents ranging from 0.12 to 0.42 wt pct have been studied to determine the effect of transformation structures on strength and toughness. The strength and toughness were, respectively, evaluated with the yield stress (0.2 pct proof stress) in tensile tests under ambient temperature and ductile-brittle transition temperature (DBTT) in Charpy impact tests. The significant conclusions are as follows: well-defined packets are observed in martensitic and lower bainitic structures, and in this case the packet diameter is the primary microstructural parameter controlling the yield stress and DBTT. The mechanical properties are also improved to a lesser degree with decreasing width of the lath present within the packet. If the steel has an upper bainitic structure, the packet is composed of well-defined blocks, and the block size controls the yield stress and DBTT.
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Tomita, Y., Okabayashi, K. Effect of microstructure on strength and toughness of heat-treated low alloy structural steels. Metall Trans A 17, 1203–1209 (1986). https://doi.org/10.1007/BF02665319
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DOI: https://doi.org/10.1007/BF02665319