1.Structural alloy steel (structural alloy steel) refers to steel that is used as mechanical parts and various engineering components and contains one or several alloying elements in a certain amount.Due to the suitable hardenability of alloy structural steel, after suitable metal heat treatment, the microstructure is uniform sorbite, bainite or extremely fine pearlite, so it has high tensile strength and yield ratio. (generally around 0.85), high toughness and fatigue strength, and low toughness-brittleness transition temperature, can be used to manufacture machine parts with larger cross-sectional dimensions

2.The role of alloying elements

There are three aspects:

①Increase the hardenability of steel. Hardenability refers to the depth of quenched martensite layer from the surface layer when the steel is quenched, which is the main parameter to obtain good comprehensive performance. Except Co, almost all alloying elements such as Mn, Mo, Cr, Ni, Si and C, N, B, etc. can improve the hardenability of steel, among which Mn, Mo, Cr, B have the strongest effect, followed by Ni , Si, Cu. The strong carbide forming elements such as V, Ti, Nb, etc., can only increase the hardenability of steel when they are dissolved in austenite.

② affect the tempering process of steel. Since alloying elements can hinder the diffusion of various atoms in the steel during tempering, they generally play a role in delaying the decomposition of martensite and the aggregation and growth of carbides compared with carbon steel at the same temperature, thereby improving the The tempering stability of steel, that is, improving the tempering softening resistance of steel, the effect of V, W, Ti, Cr, Mo, Si is more significant, and the effect of Al, Mn, Ni is not obvious. Steels containing high content of carbide forming elements such as V, W, Mo, etc., when tempered at 500 to 600 °C, precipitate fine and dispersed special carbide spots such as V4C3, Mo2C, W2C, etc., replacing some of the coarser alloys Cementite, so that the strength of the steel no longer decreases but increases, that is, secondary hardening occurs. Mo can prevent or weaken the temper brittleness of steel.

③ Affect the strengthening and toughening of steel. Ni strengthens ferrite by solid solution strengthening; carbide forming elements such as Mo, V, Nb increase the yield strength of steel by both dispersion hardening and solid solution strengthening; carbon has the most significant strengthening effect. In addition, the addition of these alloying elements generally refines the austenite grains and increases the strengthening effect of the grain boundaries. The factors affecting the toughness of steel are complex. Ni improves the toughness of steel; Mn tends to coarsen the austenite grains and is sensitive to temper brittleness; reducing the content of P and S and improving the purity of the steel are important for improving the toughness of the steel. effect.

About us

  Dongguan Songshun Mould Steel Co., Ltd. is an Indusrtial and trading company with 2 warehouses that manufactures good & high quality kinds of steels starting from 2012. The company provides the customized products and OEM service. What´s more, we keep the mass stock of over 20000 tons. In those years, we offer a wide range of steels to our customers from all over the world. And we enjoy high praise among them.

 We warmly welcome new and old customers to establish good and long term relationship with us based on equality and mutual assistance.

Feel free to contact us,we are glad to serve for you.

Songshun Always Open the Door for You.

songshunmoldsteel41404340