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Steel 50KHFA

Description

Steel 50KHFA

Steel 50HFA: 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 50HFA.

General information about steel 50HFA

Substitute brand
steel: 60S2A, 50HGFA, 9HS.
Delivery type
Circle 50khfa, sheet 50khfa, wire 50khfa, rolled sections, including shaped: GOST 14959−79, GOST 2590−71, GOST 2591−71, GOST 2879−69, GOST 7419.0−78 — GOST 7419.8−78. Calibrated bar GOST 7417−75, GOST 8559−75, GOST 8560−78. Polished bar and silver bar GOST 14955−77, GOST 7419.0−78 — GOST 7419.8−78. Tape GOST 2283−79. Strip GOST 103−76, GOST 4405−75. Forgings and forged billets GOST 1133−71, GOST 8479−70.
Application
heavily loaded critical parts, which are subject to high fatigue strength requirements, springs operating at temperatures up to 300 ° C and other parts.

Chemical composition of steel 50HFA

Chemical element %
Vanadium (V) 0.10−0.20
Silicon (Si) 0.17−0.37
Manganese (Mn) 0.50−0.80
Copper (Cu), no more 0.20
Nickel (Ni), no more 0.25
Sulfur (S), no more 0.025
Carbon (C) 0.46−0.54
Phosphorus (P), no more 0.025
Chromium (Cr) 0.80−1.10

Mechanical properties of steel 50HFA

Mechanical properties

Heat treatment, delivery condition Section, mm σ 0.2, MPa σ B, MPa δ 5 ,% KCU, J / m 2 HRC e
Steel categories: 3.3A, 3B, 3V, 3G, 4.4A, 4B. Hardening 850 ° С, oil, tempering 470 ° С. Samples 1080 1270 8    
Forgings. Hardening. Vacation 100−300 685 835 12 49  
Isothermal quenching 870 ° С, molten salt 320−330 ° С. Vacation 330 ° С, air. 20 1430 1570 6 60 44−50
Springs. Hardening 840−860 ° C. Vacation 420−450 ° С, air. fifteen 1270 1470 12   44−49
Full annealing   420 710 sixteen    
Isothermal annealing   350 650 20    
Spheroidizing leave   350 570 22    

Mechanical properties depending on the tempering temperature

vacation t, ° С σ 0.2, MPa σ B, MPa δ 5 ,% ψ,% HRC e
Quenching 850 ° С, oil.
  1580 1940 1   52−54
200 1760 2010 2   50−51
300 1640 1690 2   48−49
450   1580 4 36 45−47
500   1370 8 54 43−44

Mechanical properties depending on the section

Section, mm σ 0.2, MPa σ B, MPa δ 5 ,% ψ,% HB
Hardening 880 ° С, oil. Vacation 500 ° C.
20 1200 1320 12 42 385
40 1030 1180 fifteen 47 350
60 860 1060 eighteen 50 300

Mechanical properties versus test temperature

test t, ° C σ 0.2, MPa σ B, MPa δ 5 ,% ψ,%
Hardening 850 ° С, oil. Vacation 640 ° C.
20 840 940 22 62
200 820 910 sixteen 62
300 750 830 20 59
400 710 830 sixteen 62
500 420 500 26 74
600   380 thirty 87
Hardening 860 ° C, oil. Vacation 480 ° C. At 20 ° C HRCe 42−44
20 1370 1470 ten 42
100 1250 1410 nine 40
200 1200 1380 nine 32
300 1180 1370 thirteen 40
400 1060 1200 fifteen 60

Technological properties of steel 50HFA

Forging temperature
Beginning 1180, end 800. Cooling of workpieces with a cross-section up to 50 mm in air, 51−180 mm — in wells.
Weldability
not applicable for welded structures.
Machinability by cutting
In the hot-rolled state at HB 269 and σ B = 900 MPa K υ tv.spl. = 0.70, K υ b.st. = 0.35.
Tendency to release ability
not inclined
Flock sensitivity
not sensitive

Temperature of critical points of steel 50HFA

Critical point ° C
Ac1 752
Ac3 788
Ar3 746
Ar1 688
Mn 300

Impact strength of steel 50HFA

Impact strength, KCU, J / cm 2

Delivery status, heat treatment -25
Hardening 850 С, oil. Vacation 450 S. 31
Hardening 850 С, oil. Vacation 550 S. 37
Hardening 850 С, oil. Vacation 600 C. 67

Endurance limit of steel 50HFA

σ -1, MPa τ -1, MPa σ B, MPa σ 0.2, MPa Heat treatment, steel condition
676 519     Hardening 850 С, oil. Vacation 420 C.
666   1630 1590 Hardening 850 С, oil. Vacation 475 С. НВ 485
725   1570 1430  

Hardenability of steel 50HFA

Distance from the end, mm / HRC e
1.5 3 6 nine 12 eighteen 24 thirty 36
59 58 57.5 57.5 57.5 48 41.5 38 38
Heat treatment Crit. Diam. in oil, mm
Hardening 25−40

Physical properties of steel 50HFA

Test temperature, ° С 20 100 200 300 400 500 600 700 800 900
Normal elastic modulus, E, GPa 218 215 210 200 188 178 160 142 132  
Torsional shear elastic modulus G, GPa 85 83 81 79 73 70 62 54 50  
Density of steel, pn, kg / m 3 7800 7780 7750 7720 7680 7650 7610      
Thermal conductivity coefficient W / (m ° С) 40 39 38 37 36 33 31 29 28  
Ud. electrical resistance (p, Nom. m) 320                  
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 12.9 13.5 14.0 14.4 14.6 13.1    
Specific heat (C, J / (kg ° C)) 490 505 510 530 560 520 620 700    

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