Fracture characteristics of high-strength structural steels containing nickel and cobalt

The fracture of high-strength (σ_b=125–165 kg/mm²) steel with 0.1–0.3% C, 9% Ni, and 4% Co is completely ductile in character (dimpled) after impact tests at room temperature. With increasing amounts of carbon above 0.30%, sections of brittle fracture appear.The size of the dimples decreases with increasing amounts of carbon at all testing temperatures investigated (from +20 to ‑253°).With decreasing testing temperatures from +20 to ‑100 to ‑253° the size of the dimples decreases at all carbon concentrations, and quasibrittle sections appear. The fracture of high-strength (σ_b=125–165 kg/mm²) steel with 0.1–0.3% C, 9% Ni, and 4% Co is completely ductile in character (dimpled) after impact tests at room temperature. With increasing amounts of carbon above 0.30%, sections of brittle fracture appear. The size of the dimples decreases with increasing amounts of carbon at all testing temperatures investigated (from +20 to ‑253°). With decreasing testing temperatures from +20 to ‑100 to ‑253° the size of the dimples decreases at all carbon concentrations, and quasibrittle sections appear.