On problem of increasing the structural strength of maraging steels

On the Role of Gamma-Alpha Transformation in the Increase of the Fracture Toughness of Maraging Steel

“…The present paper is the continuation of the earlier publications [1,4,5], and its objective is to assess the contribution of the strain-induced γ→α-transformation of the stabilized austenite into the fracture toughness of the steel N18K9M5T after different regimes of thermostrengthening.…”

“…Undoubtedly, the improvement depends on the amount, morphology and properties of γ-phase (mainly, its plasticity and ability to transform into α-phase at plastic strain). The γ-phase properties and structure are determined by the type of austenite and the conditions of its formation [1,4,5]. Stabilized austenite can be subdivided into residual (γres), reverted I (γrevI) and duplex, i.e.…”

“…Stabilized austenite can be subdivided into residual (γres), reverted I (γrevI) and duplex, i.e. residual + reverted II (γres+ γrevII) [1,5].…”

Effect of Combined Tempering and Aging in the Austenite Reversion, Precipitation, and Tensile Properties of an Additively Manufactured Maraging 300 Steel

“…The 640°C for 2 hours condition led to 13% of registered austenite but with coarse precipitates of 130 nm and high interparticle spacing, which triggers a reduction of the potential mechanical strength improvement from the Orowan mechanism (Ref 4). Tempering at 600°C, followed by solubilization at 820°C for a short time (<10 min), and subsequent aging at the low temperature of, has been proved to be is useful to dissolve precipitates and maintain part of reverted austenite (Ref [13][14][15].…”

Diagrams of Isothermal Decomposition of Overcooled Austenite in Maraging Steel at Uniaxial Tensile Loading

“…To form the structure providing the desired level of mechanical and working properties, during the heat-treatment of semi-products from maraging steels annealing in the two-phase (α+γ)-field is frequently used before quenching or plastic deformation; in the two-phase (α+γ)-field the reverse martensitic γ→αtransformation (RMT) takes place accompanied by the formation of disperse retained austenite (RA) enriched with nickel [1]. There is a sufficient number of the investigations of the properties of the γ-phase as a structural component indicating an important role of retained austenite in the formation of the reliability characteristics of parts from MA steels, for example [2][3][4][5]. However, the information on the behavior of austenite at sub-zero temperatures and applied external stresses is rather limited [2,6].…”