1.7027, 20Cr4, AISI 5120, 20H – case-hardening steel

1.7027, 20Cr4, 5120, 20Ch – case-hardening steel according to ISO 683-17:2014 i GOST 4543-71.

Standard Grade
Chemical composition %
C: Si: Mn: P: S: Cr: Ni: Cu:
PN 20H
0.17-0.23 0.17-0.37 0.5-0.8 <0.035 <0.035 0.7-1.0 <0.3 -
ISO 1.7027
0.17-0.23 <0.4 0.6-0.9 <0.025 <0.030 0.9-1.2 - <0.3
GOST 20Ch - 20H
0.17-0.23 0.17-0.37 0.5-0.8 <0.035 <0.035 0.7-1.0 <0.3 <0.3
ISO 20Cr4
0.17-0.23 0.15-0.40 0.6-0.9 <0.035 <0.035 0.9-1.2 - -
AISI 5120
0.13-0.18 0.15-0.35 0.7-0.9 <0.035 <0.040 0.7-0.9 - -

20H, 1.7027, 20Cr4, 5120, 20Ch – description

Steel used for small parts with higher strength requirements than 15Cr3 steel, e.g. spindles, pins, camshafts and bushings. Weldable, machinable and cuttable steel. Weld only before carburizing.

Physical and mechanical properties

Here You can find the mechanical properties of selected alloys. Despite their similarities, they clearly differ.

Properties Grade
PN ISO GOST ISO
20H 20Cr4 20Ch 1.7027
Yield strength: Rm > 640 MPa > 850 MPa > 637 MPa -
Tensile strength: Rm > 780 MPa 820-1170 MPa > 784 MPa -
Wydłużenie: A5 11 % 9 % 11 % -
Udarność KCU, 20°C: KCU2 J/cm2 60 J/cm2 KU: 25J/cm2 59J/cm2 -
Twardość po odprężaniu: HB < 179 HB < 197 HB < 179 HB < 197 HB

Mechanical properties after hardening:

  • Diameter D: 11 mm
    • Tensile strength Rm: 820-1170 MPa
    • Yield strength Re: min 550 MPa
    • Elongation A: min 9 %
    • Impact Value KU: min 25 J
  • Diameter D: 30 mm
    • Tensile strength Rm: 750-1100 MPa
    • Yield strength Re: min 490 MPa
    • Elongation A: min 9 %
    • Impact Value KU: min 25 J
  • Diameter D: 63 mm
    • Tensile strength Rm: 670-1020 MPa
    • Yield strength Re: min 450 MPa
    • Elongation A: min 10 %
    • Impact Value KU: min 25 J

Heat treatment and plastic working

Following parameters are recommended for working and heat treatment

Treatment Grade
PN ISO GOST ISO
20H 20Cr4 20Ch 1.7027
Quenching Temperature 880℃ 860-900℃ 880℃ 860-900℃
Cooling oil, water - oil, water -
Tempering Temperature 180℃ 150-200℃ 180℃ 150-200℃
Cooling air, oil - air, oil -

We supply

  • Forgings
  • Bars
  • Wires

Substitutes, equivalents and other species designations

20H
20Ch
20Ch-Sh
20Cr
1.7027
20Cr4
SCr22
SCr420
B21
5120
C41201
20Ch-PV

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