Relaxation resistance of carbon steels in relation to the structure

TLDR: The strength and ductility of steels at 20° decrease with increasing amounts of Widmanstatten structure and increasing grain sizes, and the relaxation resistance at 430° increases, mainly due to larger grain sizes as discussed by the authors.

Abstract: 1. The strength and ductility of steels at 20° decrease with increasing amounts of Widmanstatten structure and increasing grain sizes. However, the strength characteristics of steels with Widmanstatten structure are higher, and the ductility lower, than for steels with the same grain size but rounded grains, with coarser pearlite and ferrite supersaturated with carbon. 2. When the Widmanstatten structure exceeds grade 3 the relaxation resistance at 430° increases, mainly due to larger grain sizes. At higher grdes of Widmanstatten structure the relaxation resistance decreases.