The specified limit value of alloying element content in low alloy steel

Low alloy steel is a kind of steel with a small amount of alloying elements added to ordinary carbon steel, also known as low alloy steel or ordinary low alloy steel. Low alloy steels refer to steels containing alloy elements, usually not more than 5% of the total weight, which are mainly used to improve the strength, corrosion resistance and hardenability of steel. Its characteristics are high strength, good comprehensive performance, less alloy elements, economize and convenience of use.

Low alloy steel is generally divided into low alloy high strength steel and low-alloy heat resistant steel. Low alloy high strength steel refers to the use of micro-alloy elements such as Nb, V, Ti, or two or more elements to improve the strength of the steel, the minimum yield strength can reach the top of GB700-88 is 890Mpa. Low-alloy heat-resistant steel is a kind of alloy steel which has the ability of high temperature oxidation and high temperature structural strength. It is usually used below 500℃ and there are many different kinds of complete sets of specifications and grades.

The alloys used for forming low alloy steel are usually added in the form of components. In order to keep the quantities of alloy elements in individual components within the permissible range and to ensure the uniformity of alloy components in the steel, the allowable limit values of alloy elements in low alloy steel are stipulated. The allowable limit values of various alloy elements in various alloys are different.

For example, the alloying element in low alloy steel is Cr. The limit value of Cr in steel should not exceed 0.10%. The reason is that the maximum limit of Cr in steel should not be exceeded to ensure the welding performance and to avoid hot brittleness of steel. Meanwhile, the limit value of carbon (C) in steel should not exceed 0.2%, which is to ensure the tensile strength and plasticity of member after welding.

The allowable limit values of alloy elements in low alloy steel are an important reference for users in selecting and using steel. Users should pay special attention to the alloy element content when selecting steel grades. The requirements for the individual alloy elements in the steel shall not exceed the upper limit value, so as to ensure the quality of the steel and the safety of use.

In summary, low alloy steel is a kind of special steel used in a wide range of applications. To ensure the welding performance, mechanical properties and stability of low alloy steel, the allowable limit values of alloy elements should not be exceeded. Alloy element content of steel should be checked to conform to the requirements. Only in this way can the quality of low alloy steel be guaranteed.

Low alloy steel is a kind of alloy steel which contains elements in low concentration compared with that of carbon steel. The alloy elements that are usually applied to it are manganese, silicone, nickel and molybdenum.

It has high mechanical strength, good toughness and good weldability, which deepens its application in the manufacture of various structural parts. For example, bridges, ships, automobiles, pressure vessels, oil and gas pipelines and other engineering structures.

The maximum/minimum and allowable alloy element content in low alloy steel is as follows: Carbon 0.20-0.50%, Manganese 0.80-1.25%, Silicone<= 0.35%,Phosphorus<= 0.04%,Sulfur < = 0.05%,Chromium <= 0.35%,Molybdenum<= 0.15%,Nickel <= 0.25%,Vanadium <= 0.20%,Titanium <= 0.20%. The content of alloy elements should not exceed the maximum recommended limit to maintain the consistency and stability of the steel performance.

In conclusion, Low alloy steel is a cost-effective material with a wide range of application. It has been effectively used in the construction of many modern structures, provided that strict restrictions on the content of alloy elements are met.