Contradictory change in various characterictics of the ultimate strength with a change in the rolling and heat treatment conditions and in the purity of the steel

Conclusions

• 1. The influence of the purity of steel and of the conditions of its rolling and heat treatment on the characteristics of the resistance to brittle failure may be contradictory, which is confirmed by the results of our tests.

• 2. The contradictions are manifested under conditions of substantial differences between the objects being compared with respect to the degree of plastic deformation (total bending) preceding failure (fracture).

• 3. The impact ductilityID ₀, being a single parameter for samples with various notches, was the only parameter correlating with the quality of the steel in the considered cases. The latter was evaluated both according to tests of static bending (and, most likely, of retarded failure) and according to prevailing concepts on the influence of technological factors.

• 4. Adoption of acceptance values of the standard characteristics of impact ductility with consideration of their relation to the characteristicID ₀ will improve the efficiency of using acceptance tests of impact ductility from the viewpoint of ensuring the quality of steel in articles and structural members and also when choosing the composition and processing conditions of steel.