6Cr4W3MoVNb (65Nb) die steel is a niobium-containing matrix steel. The content of alloying elements Cr, W, Mo, and V in the steel is designed from the matrix composition of the quenched W6Mo5Cr4V3 high-speed steel. The role of the alloying elements in the die is similar to that of the high-speed steel.

6Cr4W3MoVNb steel also adds a small amount of niobium, a strengthening carbide-forming element, to form highly stable NbC with the carbon of the steel grade, preventing the growth of austenite grains during quenching and heating. Compared with the die steel without Nb, the grain refinement temperature of Ashti is increased by 40~50℃, and Nb is also partially dissolved in the carbides of Cr, W, Mo, and V, which enhances the stability and makes the collective content after quenching. The carbon content is reduced, the strength and toughness of the steel are significantly improved, and the process performance of the die steel is improved.

6Cr4W3MoVNb steel application
65Nb die steel is a kind of high strength and toughness cold and hot die steel, which is widely used in the production of various cold work dies, especially suitable for cold extrusion dies for large or difficult-to-deform metals and cold forging dies with large impact loads. Sometimes it is also used for hot work molds, but mainly cold work molds. 65Nb mold steel can also be used in warm molds for steel materials. Due to the insufficient compressive strength and wear resistance of 65Nb die steel, it cannot be used for extrusion dies of 2500MPa steel materials and dies that require high wear resistance.