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Steel 18KH2N4MA

Description

Steel 18KH2N4MA

Steel 18Х2Н4МА: brand of steels and alloys. Below is the 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 18Kh2N4MA.

General information about steel 18Kh2N4MA

Substitute brand
steel: 15Х2ГН2ТРА, 20Х2Н4А.
Delivery type
Long products, including shaped: GOST 4543−71, GOST 2590−71, GOST 2591−71, GOST 2879−69, GOST 10702−78. Calibrated bar GOST 10702−78, GOST 4543−71, GOST 7417−75, GOST 8559−75, GOST 8560−78, GOST 1051−73. Polished bar and silver bar GOST 4543−71, GOST 14955−77. Strip GOST 103−76. Forgings and forged billets GOST 4543−71, GOST 1133−71, GOST 8479−70. Pipes OST 14−21−77.
Application
In a case-hardened and exposed state, it is used for critical parts that require high strength, toughness and wear resistance, as well as for parts subjected to high vibration and dynamic loads. Steel can be used at temperatures from -70 to 450 ° C.

Chemical composition of steel 18Kh2N4MA

Chemical element %
Silicon (Si) 0.17−0.37
Manganese (Mn) 0.25−0.55
Copper (Cu), no more 0.30
Molybdenum (Mo) 0.30−0.40
Nickel (Ni) 4.00−4.40
Sulfur (S), no more 0.025
Carbon (C) 0.14−0.20
Phosphorus (P), no more 0.025
Chromium (Cr) 1.35−1.65

Mechanical properties of steel 18Х2Н4МА

Heat treatment, delivery condition Section, mm σ 0.2, MPa σ B, MPa δ 5 ,% ψ,% KCU, J / m 2 HB
Bar. Hardening 950 ° C, air. Hardening 860 ° C, air. Vacation: 200 ° C, air or oil
  fifteen 835 1130 12 50 98  
Bar. Hardening 950 ° C, air. Hardening 860 ° C, air. Vacation: 550 ° C, air or oil
  fifteen 785 1030 12 50 118  
Forgings. Hardening. Vacation.
KP 685 300−500 685 835 eleven 33 39 262−311
KP 735 100−300 735 880 12 35 49 277−321
KP 785 <100 785 930 12 40 59 293−331
Annealing 890−910 ° С, cooling with a furnace
  300 390 620 ten 25   265
Normalization 920−980 ° C, air. Vacation 630−680 ° С, air.
    590 780   60   197−269
Cementation 920−950 ° C. Normalization 900−950 ° C, air. Hardening 900−950 ° С, oil. Vacation (double) 630−650 ° С, air.
  80 1270 1370 12   88 321−400

Mechanical properties at elevated temperatures

test t, ° C σ 0.2, MPa σ B, MPa δ 5 ,% ψ,% KCU, J / m 2
Hardening 880 ° С, oil. Vacation 560 ° С
20 1090 1240 12 61 127
200 1060 1190 12 60 137
300 1050 1200 114 64 118
400 960 1060 fourteen 69 108
500 810 880 fourteen 70 98
550 710 750 sixteen 73 108
Sample 6 mm in diameter, 30 mm long, rolled. Deformation rate 16 mm / min. Strain rate 0.009 1 / s.
700 225 265 31 69  
800 73 130 35 34  
900 55 79 22 23  
1000 41 55 31 36  
1100 24 36 63 100  
1200 20 25 46 100  

Mechanical properties depending on the tempering temperature

vacation t, ° С σ 0.2, MPa σ B, MPa δ 5 ,% ψ,% KCU, J / m 2
Hardening 850 ° С, oil.
200 1170 1470 12 64 114
300 1140 1390 12 64 98
400 1040 1280 12 63 86
500 950 1180 thirteen 66 92
600 710 940 19 73 183

Mechanical properties depending on the section

Heat treatment, delivery condition Section, mm σ 0.2, MPa σ B, MPa δ 5 ,% ψ,% KCU, J / m 2 HRC e
Hardening 860 ° C, oil. Vacation 200 ° С
Sample cutting location — center 40 1070 1300 fourteen 69 150 43
Sample cutting location — center 60 1110 1250 fifteen 62 140 41
Sample cutting place — 1 / 2R 80 1130 1250 12 54 170 42
Sample cutting place — 1 / 2R 100 1100 1230 fifteen 63 160 40
Sample cutting location — 1 / 3R 120 1090 1220 thirteen 60 160 41
Hardening 860 ° C, water. Vacation 200 ° С
Sample cutting location — center 40 1220 1420 thirteen 66 110 45
Sample cutting location — center 60 1280 1420 thirteen 61 120 45
Sample cutting place — 1 / 2R 80 1250 1390 12 45 150 45
Sample cutting place — 1 / 2R 100 1210 1360 thirteen 57 130 44
Sample cutting location — 1 / 3R 120 1240 1340 12 42 140 41

Technological properties of steel 18Х2Н4МА

Forging temperature
The beginning is 1200, the end is 800. Slow cooling up to 150 C followed by high vacation no later than 4−6 hours.
Weldability
difficult to weld. Welding methods: RDS, ADS submerged arc, EShS. Heating and subsequent heat treatment are required.
Machinability by cutting
at HB 277−321 σ B = 880 MPa K υ tv.spl. = 0.72, K υ b.st. = 0.63.
Tendency to release ability
not inclined
Flock sensitivity
sensitive

Temperature of critical points of steel 18Kh2N4MA

Critical point ° C
Ac1 700
Ac3 810
Ar3 400
Ar1 350
Mn 336

Impact strength of steel 18Kh2N4MA

Impact strength, KCU, J / cm 2

Delivery status, heat treatment +20 -20 -40 -60
Hardening 850 С, oil. Vacation 170 C, air. 143 134 130 114
Tempering 880 C, oil. Vacation 560 C. bw = 1310 MPa. 108   88  

Endurance limit of steel 18Х2Н4МА

σ -1, MPa τ -1, MPa n σ B, MPa σ 0.2, MPa Heat treatment, steel condition
540   5E + 6 1360 1070 Hardening 850 С, oil. Vacation 180 C.
475   5E + 6 1220 1140 Hardening 850 С, oil. Vacation 400 S.
540 228 5E + 6 1270    
470 226 5E + 6 910    
696     1230 1110 HB 383
774     1300 1180 HB 404

Hardenability of steel 18Kh2N4MA

Distance from the end, mm / HRC e
1.5 nine eleven fifteen 20 25 thirty 40 50
40.5−48.5 40.5−48.5 39.5−47.5 39.5−47.5 38.5−46.5 37.5−46.5 36.5−45.5 35−45.5 32−44.5
 

Physical properties of steel 18Kh2N4MA

Test temperature, ° С 20 100 200 300 400 500 600 700 800 900
Normal elastic modulus, E, GPa 200 165 141   139          
Density of steel, pn, kg / m 3 7950 7930 7900 7860 7830 7800 7760      
Thermal conductivity coefficient W / (m ° С)   36 36 35 35 34 33 32 thirty  
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) 11.7 12.2 12.7 13.1 13.5 13.9        

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