Correct Answer - Option 2 : Vanadium
Explanation:
High-speed steels are used for cutting metals at a much higher cutting speed than ordinary carbon tool steels. The high-speed steels have the valuable property of retaining their hardness even when heated to red heat. Most of the high-speed steels contain tungsten as the chief alloying element, but other elements like cobalt, chromium, vanadium, etc. may be present in some proportion.
18-4-1 High-speed steel- contains 18 percent tungsten, 4 percent chromium, and 1 percent vanadium.
Effect of alloying elements in HSS
Vanadium:
- Vanadium is added to high-speed-steel as a scavenger to remove slag impurities and to reduce nitrogen levels in the melting operation.
- It also increases the cutting efficiency of the tools.
- The addition of Vanadium promotes the formation of very hard carbides which increase the wear resistance of the tool.
Chromium:
- It is mainly responsible for hardenability
- The addition of chromium reduces oxidation and scaling during heat treatment.
- At 4% of concentration, it gives the best compromise between hardness and toughness.
Manganese:
The concentration of manganese is not high as it increases the brittleness and the danger of cracking upon quenching.
