20Ch2N4A, 18NiCrMo14 - Case-hardening steel

Case-hardening steel 20Ch2N4A intended for heavy duty parts of aircrafts and aircraft structures according to PN-72/H-84035.

StandardsSteel Grades
Chemical composition %
C:Mn:Si:P:S:Cr:Mo:Ni:V:Ti:Cu:N:W:
PN20H2N4A
0.16 - 0.220.30 - 0.600.17 - 0.37<0.030<0.0251.25 - 1.65-3.25 - 3.65--<0.2--
GOST20Ch2N4A - 20Х2Н4А - 20Kh2N4A
0.16 - 0.220.30 - 0.600.17 - 0.37<0.025<0.0251.25 - 1.65<0.153.25 - 3.65<0.05<0.03<0.3<0.008<0.2
UNE18NiCrMo14 - 18 NiCrMo 14 - F-1556 - F1556
0.14 - 0.200.40 - 0.700.15 - 0.40<0.035<0.0351.30 - 1.600.15 - 0.253.25 - 3.75-----
ČSN
STN
ČSN 16 523 - ČSN 16523
0.12 - 0.190.30 - 0.600.17 - 0.37<0.035<0.0351.20 - 1.75-3.25 - 4.00-----
SAE
AISI
SAE 3316 - AISI E3316 - AISI E 3316
0.14 - 0.190.45 - 0.600.20 - 0.35<0.025<0.0251.40 - 1.75-3.25 - 3.75-----
GB/T20Cr2Ni4A - 43203
0.17 - 0.230.30 - 0.600.17 - 0.37<0.025<0.0251.25 - 1.65-3.25 - 3.65--<0.25--
JISSFVQ 3 - SFVQ3
<0.230.20 - 0.40<0.40<0.020<0.0201.50 - 2.000.40 - 0.602.75 - 3.90<0.03----

20H2N4A - Description and purpose

Steel for thermal improvement and carburization with high nickel content intended to particularly heavy duty machine parts and aircraft engines. It is characterized by very good hardenability, high core strength and high hardness. Steel for large dimensions parts such as sprockets, heavy duty screws, rocker arms, piston pins, shafts and bushings Products mode of 20H2N4A steel grade are not suitable for welding.nia.

Mechanical and physical properties

  • Tensile strength Rm > 1270 MPa
  • Yield point Re >1080 MPa
  • Notch toughness KU2 > 64 J
  • Contraction Z > 45%
  • Elongation A > 9%
  • Hardness in softened state < 269 HB
  • Thermal conductivity λ = ~33,5 W ⋅ m-1 K-1
  • Pojemność cieplna cp = 490 J ⋅ kg-1 K-1
  • Density ρ = ~7,83 kg/dm3
  • Linear Expansion Factor α = ~11,1 ⋅ 10-6 K-1

Heat treatment

  • Normalising annealing at 860 - 880 °C
  • Softening annealing at 640 - 680℃
  • Carburization at 870 - 900℃
  • Carbonitriding at 850 - 880℃
  • Hardening I in oil at 845 - 875℃
  • Hardening II in oil at 760 - 800℃
  • Tempering after carburization in air or oil at 150 - 210℃
  • Cyanidizing at 840 - 860℃
  • Tempering, in order to avoid the fragility, in oil or water at a temperature of 500 - 650℃

In the 20H2N4A grade the company provides:

Substitutes, equivalents and other species designations

20Ch2N4A
20Kh2N4A
18NiCrMo14
18 NiCrMo 14
F-1556
F1556
ČSN 16 523
ČSN 16523
SAE 3316
AISI E3316
AISI E 3316
20Cr2Ni4A
43203
20Cr2Ni4
17NiCrMo14
18NiCrMo14-6
1.3533
SFVQ 3
SFVQ3
20Х2Н4А

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