15Cr 
 Alloy structural steel. Uniform digital code: A201525 Standard: GB / T 3077-1988 
 [Chemical composition] (wt) (%) Carbon C: 0.12 ~ 0.18 Si Si: 0.17 ~ 0.37 Manganese Mn: 0.40 ~ 0.70 S S: to allow the residual phosphorus content ≤ 0.035 P: ≤ 0.035 to allow the residual content of chromium Cr: 0.70 ~ 1.00 Ni: to allow the residual content ≤ 0.030 Copper Cu: ≤ 0.030 to allow the residual content 
 15Cr Alloy Steel 
 [Mechanical Properties] sample blank size (mm): 15 Heat treatment: first quenching temperature (℃): 880; coolant: water, oil the second quenching temperature (℃): 780 ~ 820; coolant: water , oil tempering heating temperature (℃): 200; coolant: water, air tensile strength σb (MPa): ≥ 735 (75) yield strength σs (MPa): ≥ 490 (50) Elongation δ5 (%) : ≥ 11 Reduction of area ψ (%): ≥ 45 Impact energy Akv (J): ≥ 55 impact toughness αkv (J/cm2): ≥ 69 (7) Brinell hardness (HBS100/3000) (annealing or high back fire state): ≦ 179 Delivery status: to heat treatment (normalizing, annealing, or tempering) or heat treatment delivery, delivery status should be indicated in the contract. 
 [Main features] which is a common low-carbon alloy carburizing steel in carburization can significantly increase the surface carbon content, increasing the carburizing depth, but when carburizing at high temperatures for a long time tendency to grain growth and the tendency to form a network carbide; the shape is simple, less demanding parts, direct cooling after carburizing quenching, but the large deformation after heat treatment, have temper brittleness of steel hardenability than 15 carbon high, the critical quenching in oil diameter 2 ~ 15mm, the critical quenching diameter of the water 6 ~ 29mm. In addition, the shaping of high cold deformation of steel, welding is good, in the annealed condition can be very good machinability. 
 [Application examples] This steel is mainly used to manufacture small cross-section of higher speed (≤ 30mm), but the heart of the Ministry of higher strength and toughness and wear-resistant surface of the carburized parts such as gears, cams, slide valve, piston, bushing, crank pins, piston pin, piston rings, couplings, shafts, bearings rings. In addition, this also can be used as a low-carbon martensitic steel hardened steel, used to make strict demands on the deformation, but requires strength and toughness of the parts