45HN, 40ChN, 40KhN - alloy steel

45HN, 40ChN, 40KhN - alloy structural steel for thermal improvement in accordance with PN-89/H-84030/04 and PN-72/H-84030.

Standards Steel Grades
Chemical Composition %
C: Mn: Si: P: S: Cr: Mo: Ni: V: Ti: Cu: N: W:
PN 45HN
0.41 - 0.49 0.5 - 0.8 0.17 - 0.37 <0.035 <0.035 0.45 - 0.75 - 1.0 - 1.4 - - - - -
GOST 45ChN - 45KhN - 45ХН
0.41 - 0.49 0.5 - 0.8 0.17 - 0.37 <0.035 <0.035 0.45 - 0.75 <0.15 1.0 - 1.4 <0.05 <0.03 <0.30 <0.008 <0.2
GOST 40ChN - 40KhN - 40ХН
0.36 - 0.44 0.5 - 0.8 <0.20 <0.035 <0.035 0.45 - 0.75 <0.15 1.0 - 1.4 <0.05 <0.03 <0.30 <0.008 <0.2
GB/T 45CrNi - A40452 - A 40452
0.42 - 0.49 0.5 - 0.8 0.17 - 0.37 <0.035 <0.035 0.45 - 0.75 <0.15 1.0 - 1.4 - - <0.30 - -
GOST 40ChN-Sh - 40KhN-Sh - 40ХН-ш
0.36 - 0.44 0.5 - 0.8 0.17 - 0.37 <0.025 <0.015 0.45 - 0.75 <0.15 1.0 - 1.4 <0.05 <0.03 <0.25 <0.008 <0.2
JIS SNC 236 - SNC 1 - SNC236 - SNC1
0.32 - 0.40 0.5 - 0.8 0.15 - 0.35 <0.030 <0.030 0.50 - 0.90 - 1.0 - 1.5 - - <0.30 - -
БДС 45ChN - 45KhN - 45ХН
0.41 - 0.49 0.5 - 0.8 0.17 - 0.37 <0.035 <0.035 0.45 - 0.75 <0.15 1.0 - 1.4 <0.05 <0.03 <0.30 - <0.2

Steel 45HN - Specification and application

Structural alloy steel with medium hardenability for thermal improvement, surface hardening - flame and inductive hardening, high strength, ductility and impact and abrasion resistance.

Used for parts of machines, motors, and motor vehicles which, due to their dimensions, cannot be carburized. The soaking of products in a cyanide salt bath increases the resistance to abrasion. The 45HN grade is also suitable for surface hardening after thermal improvement.

In addition, it has an improved surface abrasion resistance which it acquires during heating in saline bath containing cyanide. Moreover, the good feature of the 45HN grade is the resistance to deformation during hardening.

45HN steel is hard to weld, and treatment in exceptional cases should be done after softening. Used as steel for machine shafts, pinion cogwheels, toothed rims, screws, forged and folded shafts, piston rods for steam engines, hammers and pumps.

Mechanical properties of the 45HN grade

Mechanical properties
Tensile strength Rm > 1030 MPa
Yield point Re > 835 MPa
Notch toughness KCU > 56 J
Contraction Z > 45 %
Elongation A > 10 %
Density ρ ~7,83 kg/dm3
Hardness in softened state HB < 207 HB
Properties Dimensions
<16mm 16 - 40mm 40 - 100mm 100 - 160mm
Tensile strength Rm 1080 - 1230 MPa 980 - 1130 MPa 830 - 980 MPa 740 - 880 MPa
Yield point Re > 880 MPa > 780 MPa > 690 MPa > 540 MPa
Notch toughness KCU - > 40 J > 40 J -
Contraction Z > 40 % > 45 % > 45 % > 45 %
Elongation A > 9 % > 10 % > 12 % > 13 %

Heat treatment of 45HN steel

  • For large dimensions 45HN steel is hardened in oil
  • Tempering in 45HN water is done in water to avoid temper brittleness
Heat treatment type Cooling type Temperatures
Normalizing annealing in calm air 840 - 880℃
Softening annealing slow cooling 680 - 720℃
Hardening in water 810 - 840℃
w oleju 820 - 850℃
Tempering in water 550 - 650℃
in air 550 - 650℃

Welding, joining and cutting of 45HN steel

45HN steel products can be arc plasma, oxyacetylene, and propane-butane oxygen cut. Before cutting steel needs to be heated to 250 - 300 ℃. After cutting, the steel should be cooled in the air.

45HN can be frictionally, resistively or electrically welded in a softened and heat-treated state, making after the process a suitable heat treatment to maintain stable material parameters.

As mentioned above, 45HN steel does not belong to easily weldable grades. The treatment should be performed only in exceptional circumstances in the softened state of delivery of the material. Steel with a much larger dimensions requires interoperable relacing annealing.

Steel can be arc-welded with coated electrodes or in CO 2 casing with pre-heating of the material to appropriate temperatures. When the welding procedure is completed before the material has cooled down, the joints should be subjected to softening annealing.

If the conditions do not allow for treatment, the steel should be covered with mats or cooled in the hot sand.

Below the temperature table for preheating the material before welding.

Temperatures of soaking of 45HN material
Dimensions < 15mm 15 - 25mm 25 - 50mm
Temperatures 150 - 250℃ 200 - 300℃ 250 - 350℃

Substitutes, equivalents and other species designations

45ChN
45KhN
45ХН
40ChN
40KhN
40ХН
45CrNi
A40452
A 40452
40ChN-Sh
40KhN-Sh
40ХН-ш
SNC 236
SNC 1
SNC236
SNC1
45ChN
45KhN
45ХН

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