Effect of Hot Plastic Deformation on the Structure and Properties of New Corrosion-Resistant Nitrogen-Bearing 08Kh17N2AF Martensitic–Ferritic Steel

The effect of hot plastic deformation on the structure and properties of new corrosion-resistant nitrogen-bearing 08Kh17N2AF ferritic–martensitic steel has been investigated. Research data for wedgelike specimens have shown that rolling with a steel reduction up to 70% in the temperature interval 800–1100°C doles not result in specimen failure. Specimens deform uniformly both in the transverse and in the longitudinal directions without cracking on the surface and in the volume. The hardness of 08Kh17N2AF steel reaches a maximum, 41–43 HRC, after rolling in the temperature range 850–1100°C with a reduction of 30–70%. It has been found that 03Kh17N2AF steel rolled in the temperature interval 1000–900°C and cooled in air offers the best combination of strength (HRC = 40, rupture strength σ_r = 1280 MPa, yield strength σ_0.2 = 1010 MPa), ductility (δ = 17.9%, ψ = 58.8%), and impact toughness (KCU^+20°C = 0.85 MJ/m², KCU^–70°C = 0.56 MJ/m²). Such a combination of mechanical properties is due to the formation of a fine-grained structure consisting of lath martensite (66%), ferrite (20%), and retained austenite (14%) with thin ferrite and austenite lamellas between martensite laths. A pilot batch of parent sheets and malleable billets made of 08Kh17N2AF steel that are promising for producing high-load products to be used in corrosive media and at low (down to –70°C) temperatures has been prepared.