Massive vanadium additions as hard phases in powder metallurgy high-speed steels (PM HSS) lead to higher cost and bad machinability. In this study, ultrahigh alloy PM HSS with CPM121 (10W−5Mo−4Cr−10V−9Co, wt.%) as the basic composition, was directly compacted and activation sintered with near-full density (>99.0%) using pre-oxidized and ball-mixed element and carbide powders. Niobium-alloyed steels (w(V)+w(Nb)=10 wt.%) show higher hardness and wear resistance, superior secondary-hardening ability and temper resistance. But excess niobium addition (>5 wt.%) leads to coarsened carbides and deteriorated toughness. EPMA results proved that niobium tends to distribute in MC carbides and forces element W to form M₆C and WC carbides. Further, the role of rotary forging on properties of niobium-alloyed steels (S3) was researched. After rotary forging with deformation of 40%, the bending strength and fracture toughness of niobium-alloyed steels could be further improved by 20.74% and 43.86% compared with those of sample S3 without rotary forging, respectively.

在粉末冶金高速钢（PM HSS）中大量添加钒作为硬质相会导致更高的成本和较差的可加工性。在这项研究中，以CPM121（10W-5Mo-4Cr-10V-9Co，wt。％）为基本成分的超高合金PM HSS被直接压实，并通过预氧化以接近全密度（> 99.0％）的活性烧结。以及球混元素和碳化物粉末。铌合金钢（w（V）+ w（Nb）= 10 wt。％）具有更高的硬度和耐磨性，优异的二次硬化能力和抗回火性。但是过量的铌添加（> 5 wt。％）会导致碳化物变粗和韧性下降。EPMA结果证明铌趋于分布在MC碳化物中并迫使元素W形成M ₆C和WC碳化物。此外，研究了旋转锻造对铌合金钢（S3）性能的作用。旋转锻造变形40％后，与不旋转锻造样品S3相比，铌合金钢的弯曲强度和断裂韧性分别提高了20.74％和43.86％。