Structure and properties of titanium-free maraging alloys

Abstract

The changes in the structure, phase composition, and physicomechanical properties of titanium-free maraging alloys based on the Fe-15–23% Ni-(Co, Mo, V) system after heating to the single-phase α field and two-phase α + γ field have been studied. It has been established that the strengthening of N15K10M5F5-type maraging alloys is caused by the precipitation of fine particles (20–50 nm) of intermetallic phases such as the fcc Ni3(Mo, V) phase and the Fe2(Mo, V) Laves phase (in the N23K9M6 alloys, with the formation of the Ni3Mo and Fe2Mo phases). It has been shown that the two-step aging of the N15K10M5F5 alloy leads to an additional strengthening by 200–250 MPa and provides the achievement of the ultimate tensile strength σu=2400−2500 MPa. The high-strength N15K10M5F5 maraging alloys are obtained with two levels of the coercive force Hc: (a) semihard maraging alloys with Hc=20−50 Oe and σu=2100−2400 MPa; and (b) hard magnetic maraging alloys with Hc=180−230 Oe and σu=1500−1800 MPa. The high-strength titanium-free N15K10M5F5 and N23K9M6 maraging alloys possess many properties characteristic of structural, elastic, and magnetic alloys and are thus multifunctional materials. These alloys can be used for advanced high-tech articles and as high-strength magnetic materials.