Alloy steels are made by adding chemical elements such as chromium, nickel, tungsten, titanium and vanadium to the steel to give it a particular property. Commonly used alloy steel are alloy structural steel, spring steel, high-speed tool steel, ball bearing steel, stainless steel and so on. For example, high pressure vessels are made of structural alloy steel; Stainless steel has good toughness and corrosion resistance, mainly used in chemical equipment.

It is expected that by the end of this century, industrial materials, although still dominated by steel, may be partly replaced by polymer synthetic materials. At the same time, the performance of steel will be greatly improved, in addition to steel alloy, but also through the refining technology, control crystallization technology, control rolling technology, surface treatment technology and heat treatment technology to improve the performance of steel, generally expected to be 1 ~ 2 times higher than now. A variety of composite steel, pre-hardened steel, special-section steel, color stainless steel will be widely used; Hundreds of similar properties of steel are replaced by several or even thousands of steel Numbers; All kinds of steel products will be more standardized and serialized, and the steel grades used in various countries will be the same. The utilization rate of steel will be raised from the present 50% or so to 80%, the use will be more reasonable.