12CrNi2 
 12crni2 representation 12CrNi2 alloy steel standard: GB / T 3077-1988 
 Chemical composition 
 ● Chemical Composition: C: 0.10 ~ 0.17 Si Si: 0.17 ~ 0.37 Manganese Mn: 0.30 ~ 0.60 S S: to allow the residual content ≤ 0.035 
 12CrNi2 alloy steel 
 Phosphorus P: to allow the residual chromium content ≤ 0.035 Cr: 0.60 ~ 0.90 Ni-Ni: 1.50 ~ 1.90 Copper Cu: ≤ 0.030 to allow the residual content 
 Mechanical Properties 
 ● Mechanical Properties: Tensile σb (MPa): ≥ 785 (80) yield strength σs (MPa): ≥ 590 (60) Elongation δ5 (%): ≥ 12 Reduction of area ψ (%): ≥ 50 impacts Power Akv (J): ≥ 63 
 12CrNi2 alloy steel 
 Impact toughness αkv (J/cm2): ≥ 78 (8) Hardness: ≤ 207HB sample size: the sample blank standard size 15mm ● Heat treatment and microstructure: heat treatment specifications: quenching: the first 860 ℃, the second 780 ℃, water, oil cooling; tempering 200 ℃, water, air-cooled. ● Features Applications: Advanced carburizing steel, quenching and tempering, or high temperature tempering, have good mechanical properties, low temperature impact toughness is good, the notch sensitivity is small, workability and weldability is still good, but back Fire brittle, white point higher sensitivity, should be subject to secondary hardening after carburizing, special circumstances need cold treatment. 
 12crni2 representation 
 ① steel beginning of the two numbers indicate the carbon content of steel, the average carbon content of the very few that, as 40Cr, 25Cr2MoVA alloy steel pipe ② main alloying elements, in addition to individual micro-alloying elements, in general, to a few percent said. When the average alloy content of <1.5%, the steel elements are generally marked only symbols, not marked content, but prone to cause confusion in those special circumstances, after the element symbol can also be marked with the number "1", such as steel "12CrMoV" and "12Cr1MoV", the former chromium content of 0.4-0.6%, 0.9-1.2% for the latter, all the remaining ingredients the same. When the average content of alloying elements ≥ 1.5%, ≥ 2.5%, ≥ 3.5% ... ..., the symbol of the element content should be marked on the back, can be expressed as the corresponding 2,3,4 ... etc. For example 18Cr2Ni4WA. ③ steel vanadium V, Ti Ti, Al AL, boron B, RE alloys of rare earth elements are micro-alloying elements, although very low levels, should bid out in steel. For example 20MnVB steel. To 0.07-0.12% vanadium, boron 0.001-0.005%. ④ High quality steel in the steel should be added the last "A", as distinct from the general high quality steel. ⑤ special purpose alloy steel, steel, known (or suffix) on behalf of the steel uses symbols. For example Lo dedicated 30CrMnSi riveting steel, steel, said to ML30CrMnSi. Alloy seamless pipe and the existing relationship and differences between the two, can not be confused. Alloy steel pipe is produced in accordance with the material (ie material) to define the name suggests is made of alloy tube; and seamless steel pipe according to the production process (with seamless sewing) to the definition, is different from the seamless seamed tube, including the Longitudinal and spiral.