Role of harmful impurities in failure of high-strength steels

Conclusions The high-strength, medium-alloy, martensitic steels subjected to low-temperature tempering are characterized by intragranular adsorption of harmful impurities, which reduces the microductility of intragranular failure. Two types of failure take place in this case: fine-dimpled for the steels with _B 1700 MPa, and quasicleavage with _B 1850 MPa.Fine-dimpled failure is associated with adsorption of harmful impurities at the carbide-matrix and fine nonmetallic inclusion-matrix interfacial boundaries. Quasicleavage is supported by adsorption of phosphorus and sulfur on intragranular interfaces: inherited austenite boundaries, subboundaries, martensite crystal boundaries.A reduction of the content of free phosphorus and sulfur increases the microductility of the fracture surfaces of the high-strength steels and greatly increases the fracture toughness and reliability of the steel in service.Translated from Fiziko-Khimicheskaya Mekhanika Materialov, Vol. 27, No. 5, pp. 89–94, September–October, 1991.     

Earthquake resistance of basic structures at the Boguchany HPP

Results of investigations of the earthquake resistance of structures are analyzed.