The role of alloying elements in tungsten steel alloys

1, carbon (C): the carbon content of steel increases, yield point and tensile strength rises, but plasticity and impact decreases, when carbon 0.23% more than, steel welding performance deterioration, so used for welding of low alloy structural steel, carbon content is generlly not more than 0.20%. High carbon will also reduce the steel's resistance to atmospheric corrosion, in the open yard of high-carbon steel is easy to rust; in addition, carbon can increase the cold brittleness of steel and aging sensitivity.

2, silicon (Si): in the steelmaking process with silicon as a reducing agent and deoxidising agent, so the sedentary steel contains 0.15-0.30% of silicon. If the steel contains more than 0.50-0.60% silicon, silicon is considered an alloying element. Silicon can significantly increase the elastic limit, yield point and tensile strength of steel, so it is widely used as spring steel. In the tempered structural steel by adding 1.0-1.2% of silicon, the strength can be increased by 15-20%. Silicon and molybdenum, tungsten, chromium and other combinations, there is to improve corrosion resistance and oxidation resistance, can manufacture heat-resistant steel. Mild steel containing 1-4% silicon has very high magnetic conductivity and is used in the electrical appliance industry to make silicon steel sheets. Increased amount of silicon will reduce the welding performance of steel.

3, manganese (Mn): in the steelmaking process, manganese is a good deoxidiser and desulphurizer, general steel containing manganese 0.30-0.50%. In carbon steel to add more than 0.70% even if the ‘manganese steel’, the amount of steel than the general steel not only has enough toughness, and high strength and hardness, improve the hardenability of steel, improve the hot working properties of steel, such as 16Mn steel than A3 yield point of 40% higher. Steel containing 11-14% manganese has very high wear resistance, used for excavator buckets, ball mill liners and so on. The amount of manganese increases, weakening the corrosion resistance of steel, reducing welding performance.

4, phosphorus (P): in general, phosphorus is a harmful element in steel, increase the cold brittleness of steel, so that the welding performance deterioration, reduce plasticity, so that the cold bending performance deterioration. Therefore, the steel is usually required to contain less than 0.045% phosphorus, high-quality steel requirements are lower.

5, sulfur (S): sulfur in general is also a harmful element. Make steel hot brittle, reduce the ductility and toughness of steel, in forging and rolling caused by cracks. Sulfur is also unfavourable to the welding performance, reduce corrosion resistance. Therefore, the sulfur content is usually required to be less than 0.055%, and quality steel requires less than 0.040%. Add 0.08-0.20% sulfur in steel, can improve the cutting and machining properties, usually called free-cutting steel.

6, chromium (Cr): in structural steel and tool steel, chromium can significantly improve the strength, hardness and wear resistance, but at the same time reduce plasticity and toughness. Chromium can improve the oxidation resistance and corrosion resistance of steel, and therefore is stainless steel, heat-resistant steel, an important alloying element.

7, nickel (Ni): nickel can improve the strength of steel, while maintaining good plasticity and toughness. Nickel has high corrosion resistance to acids and alkalis, rust and heat resistance at high temperatures. But because nickel is a scarce resource, it should try to use other alloying elements instead of nickel-chromium steel.

8, molybdenum (Mo): molybdenum can make the steel grain refinement, improve the hardenability and thermal strength properties, at high temperatures to maintain sufficient strength and creep resistance (long term at high temperatures subject to stress, deformation, called creep). The addition of molybdenum to structural steel improves mechanical properties. It can also inhibit the brittleness of alloy steel caused by fire. In tool steel can improve the redness.

9, titanium (Ti): titanium is a strong deoxidiser in steel. It can make the internal organisation of steel dense, refine the grain force; reduce ageing sensitivity and cold brittleness. Improve welding performance. In chromium 18 nickel 9 austenitic stainless steel by adding appropriate titanium, can avoid intergranular corrosion.

10, vanadium (V): vanadium is an excellent deoxidiser of steel. Steel with 0.5% vanadium can refine the organisation grain, improve strength and toughness. Vanadium and carbon carbide formation, in the high temperature and high pressure can improve the ability to resist hydrogen corrosion.

11, tungsten (W): tungsten has a high melting point, specific gravity, is the alloying element of noble life. Tungsten and carbon to form tungsten carbide has high hardness and wear resistance. In the tool steel with tungsten, can significantly improve the red hardness and thermal strength, for cutting tools and forging moulds.

12, niobium (Nb): niobium can refine the grain and reduce the sensitivity of steel overheating and tempering brittleness, improve strength, but plasticity and toughness decreased. In ordinary low alloy steel with niobium, can improve resistance to atmospheric corrosion and high temperature resistance to hydrogen, nitrogen, ammonia corrosion. Niobium can improve welding performance. Adding niobium in austenitic stainless steel can prevent intergranular corrosion phenomenon.

13, cobalt (Co): cobalt is a rare precious metal, mostly used in special steel and alloys, such as hot steel and magnetic materials.

14, copper (Cu): Wuhan Iron and Steel with Daye Ore