Low-alloy boiler structural steel 20HM, 25HM, AISI 4130, SAE 4130 and 25CrMo4 for thermal improvement and high temperature operation in accordance with PN-89 / H-84030/04, PN-75 / H-84024, EN 10083-3 EN 10269.

 

StandardsSteel Grades
Chemical Composition %
C:Mn:Si:P:S:Cr:Mo:Ni:V:Ti:Cu:N:W:Al:
PN25HM
0.22 - 0.290.40 - 0.700.17 - 0.37<0.035<0.0350.8 - 1.10.15 - 0.25<0.3------
PN20HM
0.19 - 0.260.50 - 0.800.15 - 0.35<0.035<0.0350.9 - 1.20.4 - 0.5<0.6-----<0.02
GOST20ChM - 20KhM - 20ХМ
0.15 - 0.250.40 - 0.700.17 - 0.37<0.035<0.0350.8 - 1.10.15 - 0.25<0.3<0.05<0.03<0.3<0.008<0.2-
EN
DIN
25CrMo4 - 1.7218 - 25 CrMo 4 - 7218
0.22 - 0.290.60 - 0.90<0.4<0.025<0.0350.9 - 1.20.15 - 0.30-------
DIN
SEW
24CrMo5 - 24 CrMo 5 - 1.7258 - 7258 - DIN 17240 / SEW 550
0.20 - 0.280.50 - 0.80<0.4<0.035<0.0350.9 - 1.20.20 - 0.35<0.6------
ISO20CrMo4 - 20 CrMo 4 - 1.3567 - 3567
0.17 - 0.230.60 - 0.90<0.4<0.025<0.0300.9 - 1.20.15 - 0.25---<0.3--<0.05
AISIAISI 4130 / SAE 4130
0.28 - 0.330.40 - 0.600.20 - 0.35<0.035<0.0400.8 - 1.10.15 - 0.25-------
GB/T30CrMo
0.26 - 0.340.40 - 0.700.17 - 0.37<0.035<0.0350.8 - 1.10.15 - 0.25<0.3--<0.3---

 

25CrMo4 - specification and applications

25HM steel, which is a Polish equivalent of 25CrMo4, is alternately classified as structural steel for heat improvement and as a boiler steel designed to work at elevated temperatures. It exhibits very good strength properties, high ductility, weldability and good hardenability. Compared to the 35HM and 34CrMo4 grades, after heat treatment it has slightly worse strengths, but it makes up for the lower properties with much better ductility.

25HM achieves best durability values at dimensions up to 65mm after hardening in water, while after hardening in oil at dimensions and thicknesses up to 40mm. It is most often found in a heat-treated or softened state - less commonly in the normalized state.

For use in high temperature applications - the power industry - this steel is used in the production of parts working at 450 - 530 ℃, which exhibit creep resistance: flanges and welds for pipes, covers, nuts, heavy-duty screws, turbine rotors, turbine blades, toothed shafts, steam pipes, control parts, and levers.

Dla zastosowań pracy w podwyższonych temperaturach - przemysł energetyczny - opisywana stal znajduje zastosowanie w produkcji części pracujących w temperaturach 450 - 530℃, które wykazują odporność na pełzanie, czyli: kołnierzy i wieńcy spawanych do rur, pokryw, nakrętek, obciążonych śrub, łopatek i wirników turbin, tarczy turbin, wałów uzębionych, przewodów parowych, części sterujących, drągów oraz dźwigni.


Mechanical properties of 25HM / 25CrMo4 / 1.7218 steel

  • Tensile strength, Rm > 740 MPa
  • Yield point, Re > 590 MPa
  • Contraction Z > 55%
  • Elongation A > 15%
  • Density = ~ 7,85 g/cm3
  • Notch toughness > 80 J
  • Hardness in softened annealed state < 217 HB

 


Własności mechaniczne dla poszczególnych przekrojów

  • Tensile strength, Rm
    • dimensions and thickness <16mm = 880 - 1030 N/mm2
    • dimensions and thickness 16 - 40mm = 780 - 930 N/mm2
    • dimensions and thickness 40 - 100mm = 690 - 830 N/mm2
    • dimensions and thickness 100 - 160mm = 640 - 780 N/mm2
    • dimensions and thickness 160 - 250mm = 640 - 780 N/mm2
  • Yield point, Re
    • dimensions and thickness <16mm = > 690 N/mm2
    • dimensions and thickness 16 - 40mm = > 590 N/mm2
    • dimensions and thickness 40 - 100mm = > 490 N/mm2
    • dimensions and thickness 100 - 160mm = > 440 N/mm2
    • dimensions and thickness 160 - 250mm = > 410 N/mm2
  • Contraction, Z
    • dimensions and thickness <16mm = > 50%
    • dimensions and thickness 16 - 40mm = > 50%
    • dimensions and thickness 40 - 100mm = > 55%
    • dimensions and thickness 100 - 160mm = > 55%
    • dimensions and thickness 160 - 250mm = > 55%
  • Elongation, A
    • dimensions and thickness <16mm = > 12%
    • dimensions and thickness 16 - 40mm = > 14%
    • dimensions and thickness 40 - 100mm = > 15%
    • dimensions and thickness 100 - 160mm = > 16%
    • dimensions and thickness 160 - 250mm = > 16%

 


Heat treatment and its process

  • Soft annealing a t680 - 720℃ with slow cooling in the furnace
  • Normalizing annealing at 860 - 900 °C with slow cooling in air
  • Hardening in oil or water at 840 - 880℃
  • Tempering at 540 - 680 °C with cooling in air
  • Eelief annealing at 650 - 700℃

 


Creep limit and creep resistance of 25HM steel

Properties (MPa)Temperatures
420℃430℃440℃450℃460℃470℃480℃490℃500℃510℃520℃530℃540℃550℃
Rz/100003873643383112832552272001771531331149578
Rz/10000030828025322620017815713611810082665136
R1/10000274258242227210195179163147130115988164
R1/100000221203186171155141127112988369543925
R0,2/100002041881751621491351241121008877665546
R0,2/1000001651511381261131008775645342322418

 


In the above mentioned grades the company provides:

 


In the above mentioned grades the company provides:

25CrMo4, 25 CrMo 4, 24CrMo5, 24 CrMo 5, 1.7218, 7218, 1.7258, 7258, 20ChM, 20KhM, 20CrMo4, 20 CrMo 4, 1.3567, 3567, Blachy AISI 4130, Blachy SAE 4130, Rury AISI 4130, Rury SAE 4130, 30CrMo, G26CrMo4, 1.7221, 4130H, SF-5, 20CrMo, CSN 15130, 30CrMo4, 30 CrMo 4, 1.7216, 25CD4, 25 CD 4, 23CrMo5, 23 CrMo 5, MCrMo, IASC7218, 20HM, 25HMA, L25HM, 30HM, 26MoCr11, 26 MoCr 11, T 30CrMo3, F-222, G41300, H41300, G41310, H41304, C4730, 20ХМ, 30ХМ.


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