40NiCrMo7, AISI 4340, 40NiCrMo6, 1.6565 - Alloy steel for thermal improvement, for turbine parts up to 450 ℃, and aviation products according to NF A37-502, UNI 6926.

 

Standards Steel Grades
Chemical Composition %
C: Mn: Si: P: S: Cr: Mo: Ni: V: Ti: Cu: N: W:
PN 40HNMA
0.37 - 0.44 0.50 - 0.80 0.17 - 0.37 <0.03 <0.025 0.60 - 0.90 0.15 - 0.25 1.25 - 1.65 - - - - -
UNI 40 NiCrMo 7 - 40NiCrMo7 - NCM 4
0.38 - 0.43 0.50 - 0.80 0.15 - 0.40 <0.025 <0.020 0.70 - 0.90 0.20 - 0.30 1.65 - 2.00 - - - - -
DIN 40 NiCrMo 6 - 1.6565 - 40NiCrMo6 - 6565
0.35 - 0.45 0.50 - 0.70 0.15 - 0.35 <0.035 <0.035 0.90 - 1.40 0.20 - 0.30 1.40 - 1.70 - - - - -
AFNOR 40 NCD 7 - 40NCD7
0.38 - 0.43 0.65 - 0.85 0.15 - 0.35 <0.025 <0.025 0.70 - 0.90 0.20 - 0.30 1.65 - 2.00 - - - - -
EN 40NiCrMo4KD - 40NiCrMo4 - 40 NiCrMo 4 KD
0.36 - 0.43 0.50 - 0.80 0.15 - 0.40 <0.035 <0.035 0.60 - 0.90 0.15 - 0.35 0.70 - 1.30 - - - - -
GOST 40ChN2MA - 40KhN2MA - 40ХН2МА
0.37 - 0.44 0.50 - 0.80 0.17 - 0.37 <0.025 <0.025 0.60 - 0.90 0.15 - 0.25 1.25 - 1.65 <0.05 <0.03 <0.30 <0.008 <0.2
UNS
AISI
ASTM
AISI 4340M - AISI 4340 - AISI 4340H - UNS G43400
0.38 - 0.43 0.65 - 0.85 0.22 - 0.35 <0.012 <0.12 0.70 - 0.95 0.35 - 0.45 1.65 - 2.00 <0.05 - - - -
DIN 40 NiCrMo 8-4 - 6562 - 40NiCrMo8-4 - 1.6562
0.37 - 0.44 0.70 - 0.90 0.20 - 0.35 <0.020 <0.015 0.70 - 0.95 0.30 - 0.40 1.65 - 2.00 - - - - -

 

40HNMA, 40NiCrMo7, AISI 4340 - Destination and specification

Structural alloy steel with very good strength properties and particularly high hardening properties, used for thermal improvement on highly stressed machine parts exposed to impact, twisting and vibration, where suitable impact strength is indicated.

Unlike other heat treatment products, 40HNMA does not exhibit tendency to temper brittleness, and the products made of it show the best mechanical properties, among others, strength at dimensions of about 150mm. 40HNMA steel is a grade for hardening in oil at temperatures of 810 - 840 ℃. Tempering is carried out at temperatures between 550 ° c.

The products made of this steel are primarily designed for turbine components and subassemblies that operate at temperatures up to ~ 450 ℃, as aviation steel for heavy-duty aircraft parts, axles and shafts, and parts of internal combustion engines.

The general purpose is also geared towards specialized machine parts such as: crank shafts, connecting rods, propeller hubs, control parts, compressor parts, single disc rotors, pump parts, press parts, multi-disc rotors, large non-coal gear wheels, steam turbine drums, steam turbine blades, large cross-section screws, steam turbine shafts, and control parts.


40HNMA, 40NiCrMo7, AISI 4340 steel - mechanical properties

Mechanical properities
Yield point Re > 830 MPa
Tensile strength Rm > 980 MPa
The density of steel ρ 7,85 kg/dm3
Hardness in softened state HB < 269 HB
Contraction Z > 55%
Notch toughness KU2 > 80 J
Elongation A > 12%

 


Mechanical properties depending on the dimensions

Properties for individual dimensions
Mechanical properties Dimensions and diameters
do 16mm 16 - 40mm 40 - 100mm 100 - 160mm 160 - 250mm
Yield point Re > 980 MPa > 880 Mpa > 780 Mpa > 690 MPa > 640 MPa
Tensile strength Rm 1180 - 1370 MPa 1080 - 1280 MPa 980 - 1180 MPa 880 - 1080 MPa 830 - 980 MPa
Contraction Z - - - - -
Notch toughness KU2 > 32 J > 40 J > 48 J > 48 J -
Elongation A > 9 % > 10 % > 11 % > 12 % > 12 %

 


Heat treatment - processes and temperatures

Thermal treatment
Heat treatment type Normalizing annealing Softening annealing Hardening Tempering
Cooling in calm air slow in oil in air
Temperatures of the processes 840 - 870℃ 660 - 700℃ 810 - 840℃ 550 - 650℃

 


Welding, joining and cutting of 40HNMA steel

40HNMA steel products are difficult to weld. Welding procedures should be avoided and, in exceptional cases, to join materials in softened state use CO2 welding or the arc method. When welding, the products should be heated to high temperatures of 150-400 ℃ depending on the cross section of the material. For large-scale products, inter-operative relaxing annealing should be applied.

After the procedure and before the temperature drop, new joints are recommended to heat up or to use on them softening annealing. In the absence of conditions for carrying out thermal treatments, fresh connections are to be cooled down in the furnace. N the case of welding in hardened and tempered state - the places and areas of joints will have worse mechanical properties due to the influence of high temperature. For the restoration of previous properties, proper heat treatment must be carried out.

As in the case of welding, 40HNMA products should also be heated to suitable temperatures when cutting with gas and plasma. The cuts are made in the range 250 - 350 ℃ and the surfaces of the cut products should be cooled in the air. When it comes to gas cutting methods, the cutting should be made with oxyacetylene blowpipe or propane-butane-oxygen torch. The described grade can also be welded by electrical welding, resistance welding, or friction welding, in a heat-treated or softened state.


In this grade the company provides:

 


List of equivalents and other determinations of 40HNMA grade:

40NiCrMo8-4, 40 NiCrMo 8-4, 1.6562, AISI 4340, 6562, AISI 4340M, ASTM A 646 Grade 7, A646 Gr. 7, UNS G43400, UNS G 43400, 40ChN2MA, 40KhN2MA, 40ХН2МА, 40NCD7, 40 NCD 7, 40NiCrMo6, 1.6565, 6565, 40ChN2MA-Sh, 40KhN2MA-Sh, 818M40, 40ХН2МА-ш, 818 M 40, 40NiCrMo7, AISI 4337, 40 NiCrMo 7, UNS G 43370, ASTM A 519 E4337, ČSN 16341, ČSN 16 341, AISI 4340H, 40CrNiMoA, NCM 4.


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