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Steel 20KH2N4A

Description

Steel 20KH2N4A

Steel 20Kh2N4A: 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 20X2H4A.

General information about steel 20X2H4A

Substitute brand
steel: 20ХГНР, 15ХГН2ТА, 20ХГНТР.
Delivery type
Circle 20x2n4a, 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. Pipes OST 14−21−77.
Application
Gears, pinion shafts, pins and other case-hardened, especially critical, highly loaded parts, which are subject to requirements for high strength, ductility and toughness of the core and high surface hardness, operating under shock loads and at negative temperatures.

Chemical composition of steel 20X2H4A

Chemical element %
Silicon (Si) 0.17−0.37
Manganese (Mn) 0.30−0.60
Copper (Cu), no more 0.30
Nickel (Ni) 3.25−3.65
Sulfur (S), no more 0.025
Carbon (C) 0.16−0.22
Phosphorus (P), no more 0.025
Chromium (Cr) 1.25−1.65

Mechanical properties of steel 20X2H4A

Fur. properties at elevated temperatures
Fur. properties depending on tempering temperature
Fur. properties depending on the section
Fur. bar properties

Mechanical properties at elevated temperatures

test t, ° C σ 0.2, MPa σ B, MPa δ 5 ,% ψ,%
Sample 10 mm in diameter, 50 mm long, forged and annealed. Deformation rate 5 mm / min. Strain rate 0.002 1 / s.
700 63 120 56 78
800 45 56 64 95
900 36 56 58 100
1000 22 37 63 100
1100 20 27 59 100
1150 sixteen 26 65 100
1220 sixteen 22 71 100

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 840 ° С, oil.
200 1360 1500 7 56 120
300 1280 1400 7 60 100
400 1140 1300 7 63 120
500 970 1170 ten 67 220
600 790 1000 eleven 72 235

Mechanical properties depending on the section

Section, mm σ 0.2, MPa σ B, MPa δ 5 ,% ψ,% KCU, J / m 2 HB
Quenching, tempering
thirty 820 940 12 50 80 277
50 820 940 12 50 70 277
80 820 940 12 50 70 269
120 780 900 12 50 60 262
160 760 880 12 50 60 262
200 740 860 12 50 60 262
240 720 860 12 50 60 255

Mechanical properties of the bar

Heat treatment, delivery condition Section, mm σ 0.2, MPa σ B, MPa δ 5 ,% ψ,% KCU, J / m 2 HB HRC e
Hardening 860 ° C, oil. Hardening 780 ° С, oil. Vacation 180 ° C, air or oil. fifteen 1080 1270 nine 45 78    
Cementation 900−920 ° C, air. Hardening 780−810 ° С, oil. Vacation 180−200 ° C, air. 50 1050 1220 12 45 118 360 57−64
Cementation 920−950 ° C. Normalization 900−920 ° C, air or quenching 880−920 ° C, oil. Vacation 630−660 ° С, air. Hardening 780−820 ° С, oil. Vacation 150−200 ° C, air. 150 830 1080 nine 35 78 321−420 57−64

Technological properties of steel 20X2H4A

Forging temperature
Beginning 1200, end 800. Sections up to 100 mm are cooled in air, 101−350 mm — in a pit.
Weldability
difficult to weld. Welding methods: RDS, ADS submerged arc, EShS. Heating and subsequent heat treatment are required.
Machinability by cutting
After normalization and tempering at HB 259 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 20X2H4A

Critical point ° C
Ac1 710
Ac3 800
Ar1 640

Impact toughness of steel 20X2H4A

Impact strength, KCU, J / cm 2

Delivery status, heat treatment +20 -20 -40 -70
Tempering 820 С, oil. Vacation 500 S. 147 147 157  
Longitudinal specimens from forging (Quenching 880 C, oil. Quenching 780 C, oil. Tempering 200 C) 65 61 63 62
Cross specimens from forging (hardening 880 C, oil. Quenching 780 C, oil. Tempering 200 C) 32 33 35 thirty

Endurance limit of steel 20X2H4A

σ -1, MPa τ -1, MPa σ B, MPa σ 0.2, MPa Heat treatment, steel condition
617 372 1220 1050 HB 360
333 230 730 610 HB 238
382   960 680 HB 322
421   940 850  

Hardenability of steel 20X2H4A

Normalization 850 C. Hardening 840 C. Hardness for hardenability strips HRCe.

Distance from the end, mm / HRC e
3 five ten fifteen 20 thirty 40 50 60
41.5−49.5 40.5−48.5 35.5−45.5 31−40 28−36.5 25−33 23.5−31 23−30.5 22.5−30.5
 

Physical properties of steel 20X2H4A

Test temperature, ° С 20 100 200 300 400 500 600 700 800 900
Normal elastic modulus, E, GPa 203                  
Density of steel, pn, kg / m 3 7850                  
Thermal conductivity coefficient W / (m ° С)   24     eighteen          

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