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38Cr2MuA steel

25X1MF 35CRM 20CR3MOVF 25X2M1F 38CR2MUA 30CRM 30CMA

38Cr2MuA steel

38Cr2MuA steel: steel and alloys classifier. Below is systematized information on the purpose, chemical composition, types of supply, substitutes, critical point temperature, physical, mechanical, technological and foundry properties for the grade — Steel 38Cr2MuA.

General information about 38Cr2MuA steel

A substitute for the grade
38Kh2MYUA steel, 38KhVFU, 20Kh3MVF, 38Kh2YU.
Type of delivery
Round 38h2muA, bars, 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. Grinded rod and silversilver GOST 14955−77. Strip GOST 103−76. Forged and forged blanks GOST 1133−71.
Application
Steam turbine valve stems operating at temperatures up to 450 ° C, the cylinder liners of internal combustion engines, injector needles, oil pan head, atomizers, fingers, plungers, camshafts, gears, shafts, bushings and other parts.

Chemical composition of 38Cr2MoVA steel

Chemical element %
Aluminum (Al) 0.70−1.10
Silicon (Si) 0.20−0.45
Manganese (Mn) 0.30−0.60
Copper (Cu), not more 0.30
Molybdenum (Mo) 0.15−0.25
Nickel (Ni), not more 0.30
Sulfur (S), max. 0.025
Carbon (C) 0.35−0.42
Phosphorus (P), not more than 0.025
Chromium (Cr) 1.35−1.65

Mechanical properties of 38Cr2MuA steel

Mechanical properties

Section, mm σ0, 2, MPa σB, MPa δ5, % ψ, % KCU, J/m2 HB
Bar. Hardening at 940 °C, water or oil. Tempering at 640 °C, water or oil.
30 835 980 14 50 88  
Forgings. Hardening. Tempering.
100−300 590 735 13 40 49 235−277
Quenching 930−950°C, oil or water. Tempering 640−680°C, air.
60 880 1030 18 52   250−300
100 730 880 10 45 59  
200 590 780 10 45 59  
Hardening 950 °C, oil. Tempering 550 °C, oil.
120 780−880 930−1030 12−15 35−45 69−98 285−302

Mechanical properties at elevated temperatures

t test,°C σ0, 2, MPa σB, MPa δ5, % ψ, % KCU, J/m2
Bar. Quenching at 930−940°C, oil. Tempering at 660 °C, 5 hours tempering. NV≥255
20 650 800 17 64 157
200 580 780 17 56 152
300 570 810 18 58 127
400 550 720 20 63 127
500 420 470 25 81 98
600 270 300 26 89 98
Sample diameter 10 mm, length 50 mm, rolled and annealed. Deformation rate of 20 mm/minute. Strain rate 0.007 1/s.
800 98 110 66 95  
900 66 84 57 97  
1000 39 49 66 98  
1100 22 32 77 100  
1200 15 22 77 100  

Mechanical properties depending on tempering temperature

t tempering temperature, °C σ0, 2, MPa σB, MPa δ5, % ψ, % KCU, J/m2 HB
900 °C hardening, oil.
300 1660 1810 8 43 39 550
400 1520 1670 10 39 10 500
500 1270 1420 10 44 29 450
600 1080 1180 12 60 78 370

Mechanical properties depending on the cross section

Heat treatment, delivery condition Section, mm σ0, 2, MPa σB, MPa δ5, % ψ, % KCU, J/m2 HB
Tempering at 930−950°C, oil or water. Tempering 640−680°C, air.
  60 880 1030 18 52   250−300
  100 730 880 10 45 59  
  200 590 780 10 45 59  
Quenching 940 °C, oil. Tempering at 600 °C.
Sample cutout location — center 30 780 910 17 52 115  
Quench 940 °C, through water into oil. Tempering at 600 °C.
Sample cutout location — center 50 830 950 16 50 102  
Sample cutout location — center 80 830 940 15 50 48  
Sample cutout location — center 140 780 920 15 48 41  
Sample cutout location — center 180 710 860 15 47 36  
Sample cutout location — edge 180 780 930 14 48 39  
Sample cutout location — center 220 730 880 15 43 35  
Sample cutout location — edge 220 800 930 16 43 34  

Mechanical properties at 20 C

Heat treatment, delivery condition σ0.2, MPa σB, MPa δ5, % ψ, % KCU, J/m2
Quenching at 930−940°C, oil. Tempering at 660 °C.
Heat soaking at 500 °C. 5000 h. 640 800 20 60 152
Heat soak 550 °C 5000 h. 550 710 23 63 171

Mechanical properties in the long term strength test

Creep strength, MPa Creep rate, %/h t test,°C Ultimate long-term strength, MPa Test duration, h t test, h
196 1/100000 450      
82 1/100000 500      
14 1/100000 550      

Technological properties of 38Cr2MuA steel

Forging temperature
The beginning 1240, the end 800. Sections up to 50 mm are cooled in stacks in the air, 51−100 mm — in crates.
Weldability
Not applicable to welded structures.
Machinability
In the hardened and tempered state at HB 240−277 σB = 780 MPa K υ tv.spl. = 0.75, Kυ b.st. = 0.55.
The tempering capacity
is not inclined
Floc-sensitivity
sensitive

Temperature of 38Cr2MuA steel critical points

Critical point °С
Ac1 800
Ac3 865
Ar3 740
Ar1 665
Mn 330

38Kh2MuA steel hardness

Delivery condition, heat treatment regime NV HV
Quenching 930−950 C, oil or water. Tempering 640−680 C, air. Nitriding 520−540 C with furnace to 100 C. 269−300 850−1050

Endurance limit of 38Cr2MuA steel

σ-1, MPa n σB, MPa σ0, 2, MPa Heat treatment, state of steel
392−480 1Е+7 810 650 Quenching at 940 °C, oil. Tempering 660 C, 5 h, air. HB 255
608−617       Hardening 940 C, oil. Nitriding 500 C, 48 h.

Hardenability of 38Cr2MuA steel

Quenching at 870 °C.

Face-off distance, mm / HRCe
1.3 3 6 9 12 18 24 30 36 42
52.0 52.0 51.5 49.5 48.5 45.5 44.0 43.5 43.5 42.5
Crit. dia. in water, mm Crit. dia. in oil, mm
70 45

Physical properties of 38Cr2MoVA steel

Temperature of test, °С 20 100 200 300 400 500 600 700 800 900
Modulus of normal elasticity, E, GPa 209 202 194 190 181 174 162 147 137  
Torsional shear modulus of elasticity G, GPa 82 79 76 75 71 67 62 57 53  
Thermal conductivity coefficient W/(m — °C) 33 33 32 31 20 20 28 27 27  
Test temperature,°C 20−100 20−200 20−300 20−400 20−500 20−600 20−700 20−800 20−900 20−1000
Coefficient of linear expansion (a, 10−6 1/°C) 11.5 11.8 12.7 13.4 13.9 14.7 14.9 12.3    
Specific heat capacity (C, J/(kg -°C)) 496 517 533 546 575 609 638 676