304 steel grade Stainless Steel Seamless Tube

Stainless Steel Seamless Tube China 304 steel grade

Stainless steel tube brand "304 ' '(S30400) is the stainless steel standard (ASTM standard) of the brand name, it is 18 8 Cr - Ni - Mr Obama's typical grades of stainless steel body, because it has excellent comprehensive performance, application is very extensive, its production accounted for about 80% to the type of stainless steel.

 

Main properties of 304(06Cr19Ni10) steel

1. Excellent corrosion resistance against rust and intercrystalline corrosion.
Oxidizing acids, such as nitric acid at a concentration of less than 65% below the boiling temperature, are highly corrosive.It also has good corrosion resistance to alkali solution and most organic and inorganic acids.

2. Excellent cold and hot processing and forming performance.

We can manufacture all kinds of products, such as plate, tube, silk, ribbon, etc.

3. Good performance at low temperature.

Under the condition of - 180 ℃, strength, elongation, reduction of area is very good.Because there is no brittle transition temperature, it is often used at low temperature.

4. Good welding performance.

The usual welding method can be adopted. No heat treatment is required before or after welding.

Defects in the performance of 304 steel

Large section size steel parts are sensitive to intercrystalline corrosion after welding.Water containing c1 - water (including wet atmosphere) is very sensitive to stress corrosion.Low mechanical strength, poor cutting performance, etc.

 

As 304 steel has some defects in performance, people try to make use of its advantages and disadvantages in production and use and try their best to develop its good performance and overcome its shortcomings.Therefore, through research and development, the chemical composition of 304 derivatives was adjusted according to the specific requirements of different use environments or conditions.

 

Table 1 lists the American society of material and test 304 standard ASTM A959-04 grades of stainless steel grades and its derivative brand in China with Japan JIS, GB, ISO international and European EN standard stainless steel in comparison to the corresponding brand.Table 2 and table 6 respectively list the chemical constituents of each brand in the corresponding standards.

 

As can be seen from table 1, in astma959-04, there are 10 304 and its derivative brands.There are also 10 JIS in Japan, but there are 6 corresponding to ASTM, and the other 4 brands (SUS304J1, SUS304J2, SUS304J3 and SUS304Cu) should be 304 derivative brands developed by JIS itself.

 

In a comprehensive view of the chemical composition of 304 and its derivative brands, it can be concluded that the so-called derivative brands are some adjustments to the chemical composition of 304, and the variation of 304 brands is produced.Such as:

Carbon content: to reduce or increase carbon content.304L is ultra-low carbon 304 steel.Reducing carbon content can improve corrosion resistance, especially the sensitivity of 304 steel to intercrystalline corrosion after welding. It can be used to manufacture large cross-section welding parts under the condition of meeting the requirement of mechanical strength.304H, increase the carbon content to 0.10%, increase the strength of 304 steel, and make austenite more stable, more suitable for use in low temperature environment and non-magnetic parts than 304 steel.

 

Nitrogen content: add nitrogen.304N(SUS304N1), xm-21 (SUS304N2), 304LN, etc.Due to the effect of solid solution strengthening of the nitrogen, improve the strength of 304 and 304 l steel, and does not significantly reduce the plasticity and toughness of steel, and steel's resistance to intergranular corrosion, pitting and crevice corrosion have further improved.

 

Copper content: add a certain amount of copper.Copper makes the austenite more stable.On the one hand, it can improve the corrosion resistance and corrosion resistance of steel, especially for reducing medium (such as sulfuric acid).On the other hand, it reduces the strength of steel and the hardening tendency of cold working, and improves the plasticity of steel.Such as S30430(06Crl8Nil9Cu3, SUSXM7), SUS304J3(06Crl8Nil9Cu2), etc., these steel and 304, under the action of small deformation force, can obtain greater cold deformation, more suitable for cold upsetting, cold extrusion as fasteners or deep drawing, etc.

 

To specifically is here, the Japanese JIS standard, the number of 304 steel derivative with 5 copper, there are three grades namely SUS304Cu, SUS304J1, SUS304J2 only used in the production of strip products, while SUS304J1 and SUS304J2 the chemical composition of the two brands, is in 304 on the basis of the larger adjustment (see table 3), reduced chromium, nickel, Cr is 15.00% ~ 18.00%, Ni is 6.00% 9.00%, also to increase the Mn to 3.00% or 5.00%,Cu content is 1.00% to 3.00%.Either manganese or copper for nickel.These two types of steel sheet bands may be suitable for the general corrosion resistance conditions through cold processing (such as deep drawing, deep drawing deformation) formed parts or products.

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