20CrNi 
 20crni representation 20CrNi work load for the manufacture of large high carburizing important parts such as gears. Keys. The shaft. Piston pin. Splined shaft; also be used as a high impact toughness of quenched and tempered parts edit this paragraph 20crni introduction 
 20CrNi Standard: GB / T 3077-1988 features: a high load for the manufacture of large and important work of the carburized parts such as gears. Keys. The shaft. Piston pin. Splined shaft; also be used as a high impact toughness quenched parts edit this paragraph 20crni chemical composition 
 ● Chemical Composition: C: 0.17 ~ 0.23 Si Si: 0.17 ~ 0.37 
 20CrNi alloy steel 
 Manganese Mn: 0.40 ~ 0.70 S, allows the residual sulfur content ≤ 0.035 P ≤ 0.035 P to allow the residual content of chromium Cr: 0.70 ~ 1.00 Ni-Ni-Ni: 1.00 ~ 1.40 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 (%): ≥ 10 Reduction of ψ (%): ≥ 50 impacts Power Akv (J): ≥ 63 impact toughness αkv (J/cm2) ≥ 78 (8) Hardness: ≤ 197HB sample size: Sample size of 25mm rough heat treatment specifications 
 ● Heat treatment and microstructure specifications: Heat treatment specifications: quenching 850 ℃, water, oil cooling; tempering 460 ℃, water-cooled, oil-cooling. ● Delivery status: to heat treatment (normalizing, annealing, or tempering) or heat treatment delivery, delivery status should be indicated in the contract. 
 20crni 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