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Steel 20ХН3А

Description

Steel 20ХН3А

Steel 20ХН3А: a brand of steels and alloys. Below is a systematized information on the purpose, chemical composition, types of supplies, substitutes, temperature of critical points, physical, mechanical, technological and casting properties for the grade — Steel 20XN3A.

General information about steel 20ХН3А

Substitute brand
steel: 20HGNR, 20HNG, 38XA, 15H2GN2TA, 20HGR.
Delivery type
Circle 20хн3а, long products, including shaped: GOST 4543−71, GOST 2590−71, GOST 2591−71, GOST 2879−69. Calibrated bar GOST 7417−75, GOST 8559−75, GOST 8560−78, GOST 1051−73. Polished bar and silver bar GOST 14955−77. Strip GOST 103−76. Forgings and forged billets GOST 1133−71, GOST 8479−70. Pipes OST 14−21−77.
Application
Gears, shafts, bushings, power pins, bolts, worms, couplings and other case-hardened parts that require high strength, ductility and toughness of the core and high surface hardness, operating under shock loads and at negative temperatures.

Chemical composition of steel 20ХН3А

Chemical element %
Silicon (Si) 0.17−0.37
Manganese (Mn) 0.30−0.60
Copper (Cu), no more 0.30
Nickel (Ni) 2.75−3.15
Sulfur (S), no more 0.025
Carbon (C) 0.17−0.24
Phosphorus (P), no more 0.025
Chromium (Cr) 0.60−0.90

Mechanical properties of steel 20ХН3А

Heat treatment, delivery condition Section, mm σ 0.2, MPa σ B, MPa δ 5 ,% ψ,% KCU, J / m 2 HB
Bar. Hardening 820 ° С, oil. Vacation 500 ° C. water or oil.
  fifteen 735 930 12 55 108  
Forgings. Hardening. Vacation
KP 590 <100 590 735 fourteen 45 59 235−277
KP 685 <100 685 835 thirteen 42 59 262−311
Cementation 920−950 ° C. Normalization 870−890 ° C, air. Vacation 630−660 ° С, air. Hardening 790−810 ° С, oil. Vacation 180−200 ° C, air.
  100 690 830 eleven 50 69 240

Mechanical properties depending on the tempering temperature

vacation t, ° С σ 0.2, MPa σ B, MPa δ 5 ,% ψ,% KCU, J / m 2 HRC e
Normalization 860 ° C, air. Hardening 810 ° С, oil.
200 1270 1510 fifteen 60 73 43
300 1260 1370 12 62 54 42
400 1180 1260 thirteen 64 59 39
500 960 1000 19 66 83 32
600 720 780 24 73 162 22

Mechanical properties depending on the section

Section, mm σ 0.2, MPa σ B, MPa δ 5 ,% ψ,% KCU, J / m 2 HRC e
Hardening 850 ° С, oil. Vacation 200 ° C, air.
five 1220 1420 12 55 86 44
fifteen 1180 1370 thirteen 65 76 44
20 1080 1270 thirteen 65 89 44
Hardening 880 ° С, oil. Vacation 600 ° C, air.
thirty 700 800 20 70 167  
50 610 730 19 71 167  
80 580 700 23 68 167  
220 510 660 fourteen 51 167  
220 570 690 23 67 157  

Technological properties of steel 20ХН3А

Forging temperature
Beginning 1220, end 800. Sections up to 100 mm are cooled in air, 101−300 mm — in a pit.
Weldability
restrictedly weldable. RDS, ADS under flux.
Machinability by cutting
In the hot-rolled state at HB 177, σ B = 610 MPa K υ b.st. = 0.95.
Tendency to release ability
inclined
Flock sensitivity
sensitive

Temperature of critical points of steel 20ХН3А

Critical point ° C
Ac1 730
Ac3 810
Ar3 700
Ar1 615
Mn 340

Impact strength of steel 20ХН3А

Impact strength, KCU, J / cm 2

Delivery status, heat treatment +20 -20 -40 -50 -60
Blank with a section of 10 mm. Hardening 850 С, oil. Vacation 200 C. 86   85    
Blank with a cross section of 30 mm. Tempering 880 C, oil. Vacation 560 С. 167   69 64  
Workpiece with a cross section of 50 mm. Tempering 880 C, oil. Vacation 560 С. 167   83 73  
Workpiece with a section of 80 mm. Tempering 880 C, oil. Vacation 560 С. 167   69    
Normalization 860 C, air. Guenching 810 С, oil. Vacation 600 C. 196 122 100   86
Billet with a section of 220 mm. Tempering 880 C, oil. Vacation 630 C. 167   118 78  

Endurance limit of steel 20ХН3А

σ -1, MPa τ -1, MPa n σ B, MPa Heat treatment, steel condition
382   1E + 6 960 Tempering 820 С, oil. Vacation 200 C.
338 225 1E + 6 730 Tempering 820 С, oil. Vacation 500 S.
421   1E + 6 940 Hardening 800 C, oil. Vacation 500 S.

Hardenability of steel 20ХН3А

Tempering 830 C.

Distance from the end, mm / HRC e
1.5 3 4.5 6 7.5 nine 12 fifteen 21 39
43−51 42−50.5 41−50 39−49 37−5-46 35.5−46 33−43 31−40.5 27.5−35.5 22−31
Amount of martensite,% Crit. Diam. in water, mm Crit. Diam. in oil, mm Crete. hardness, HRCэ
50 70−96 44−62 32−37
90 42−64 20−38 39−44

Physical properties of steel 20ХН3А

Test temperature, ° С 20 100 200 300 400 500 600 700 800 900
Normal elastic modulus, E, GPa 212 204 194 188 169 169 153 138 132  
Torsional shear elastic modulus G, GPa 83 80 76 70 68 66 59 53 51  
Density of steel, pn, kg / m 3 7850 7830   7760     7660      
Thermal conductivity coefficient W / (m ° С) 36 35 34 33 33 31 31 thirty 28  
Ud. electrical resistance (p, Nom. m) 270 300 350 450 550 650        
Test temperature, ° С 20−100 20−200 20−300 20−400 20−500 20−600 20−700 20−800 20−900 20−1000
Linear expansion coefficient (a, 10−6 1 / ° С) 11.5 11.7 12.0 12.6 12.8 13.2 13.6 11.2    
Specific heat (C, J / (kg ° C)) 494 507 523 536 565 586 624 703    

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