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30KhMA steel

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

30KhMA steel

Steel 30KhMA: Handbook of steels and alloys. Below is systematized information on the purpose, chemical composition, types of supply, substitutes, critical point temperatures, physical, mechanical, technological and foundry properties for the grade — Steel 30KhMA.

General information on steel 30KhMA

Grade substitute
Steel grades: 35KhM, 35KhRA.
Delivery type
Circle 30хМА, 30хМА pipe, bar stock, including shaped: GOST 4543−71, GOST 259071, 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, GOST 8479−70.
Application
Gears, shafts, trunnions, pins, nuts, and various other parts operating at temperatures up to 450−500 ° C.

Chemical composition of steel 30KhMA.

Chemical element %
Silicon (Si) 0.17−0.37
Manganese (Mn) 0.40−0.70
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) 0.26−0.33
Phosphorus (P), not more than 0.025
Chrome (Cr) 0.80−1.10

Mechanical properties of 30KhMA steel

Heat treatment, delivery condition Section, mm σ0, 2, MPa σB, MPa δ5, % ψ, % KCU, J/m2 HB
rod. Hardened at 880 °C, low-temperature. Tempering 540 °C, water or oil.
  15 735 930 12 55 78  
Forgings. Hardening. Tempering.
CP 395 <100 395 615 17 45 49 187−229
KP 440 100−300 440 635 16 45 59 197−235
KP 440 100−300 440 635 14 40 54 197−235
CP 490 <100 490 655 16 45 59 212−248

Mechanical properties at elevated temperatures

t test,°C σ0, 2, MPa σB, MPa δ5, % ψ, % KCU, J/m2
Hardening at 880 °C, oil. Tempering 650°C
260 590 730 20 70 186
200 490 660 21 70  
300 520 710 21 69 206
400 480 630 22 75 199
500 430 500 22 80 142
600 340 330 29 89 142
Sample diameter 6 mm, length 30 mm, pressed. Strain rate 16 mm/minute. Strain rate 0.009 1/s
800 80 130 69 67  
1000 41 56 64 100  
1200 14 26 55 100  

Mechanical properties depending on tempering temperature

t tempering temperature, °C σ0, 2, MPa σB, MPa δ5, % ψ, % KCU, J/m2 HRCe
Tempering at 880 °C, oil.
200 1320 1520 12 50 69 49
300 1330 1450 11 51 49 45
400 1220 1370 12 55 69 42
500 1080 1130 16 60 127 36

Mechanical properties depending on the cross section

Heat treatment, delivery condition Section, mm σ0, 2, MPa σB, MPa δ5, % ψ, % KCU, J/m2 HRCe
Hardening at 880 °C, oil. Tempering at 500 °C.
Specimen cut out area — center 40 650 820 17 71 147 27
Sample cutout location — center 60 630 800 17 69 157 27
Sample cutout location — ½R 80 660 790 17 67 137 25
Sample cutout location — ½R 100 610 780 18 64 147 25
Sample cutout location — 1/3R 120 620 750 16 63 137  
Tempering 880 °C, water. Tempering at 500 °C.
Sample cutout location — center 40 790 930 13 61 118 30
Sample cutout location — center 60 740 870 16 64 127 31
Sample cutout location — ½R 80 760 890 14 64 108 30
Sample cutout location — ½R 100 700 830 17 65 137 27
Sample Cutout Location — 1/3R 120 690 840 18 63 118 25

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
137 1/10000 500 186 10000 500
69 1/100000 500 127 100000 500
59 1/10000 550 108 10000 550
34 1/100000 550 69 100000 550

Temperature of 30KhMA steel critical points

Critical point °С
Ac1 757
Ac3 807
Ar3 763
Ar1 693

Impact toughness of 30XMA steel

Impact toughness, KCU, J/cm2

Delivery condition, heat treatment -20 -40 -60
Hardening 880 C, oil. Tempering 350 C.   42  
Tempering at 880 °C, oil. Tempering 550 C. 147   108

Endurance limit of 30KhMA steel

σ-1, MPa n Heat treatment, steel condition
407 1Е+7 Hardening 870 C, water. Tempering 600 C
366   HB 260. Tempering at 880 C, oil. Tempering 560 C.
304   HB 212 Tempering at 880° C in oil. Tempering at 650 °C.

Hardenability of steel 30XMA

Hardening at 880 C. Hardness of hardenability bands HRCe.

Distance from the end face, mm / HRCe
1.5 3 4.5 6 9 12 15 18 21 24
49.5−54 48−53 46−52 43.5−51 37−48 33.5−44.5 30−39.5 28−37.5 26.5−35.5 24−34.5
 

Physical properties of 30KhMA steel

Test temperature, °С 20 100 200 300 400 500 600 700 800 900
Modulus of normal elasticity, E, GPa 208 207 204 197 188 176 160      
Steel density, pn, kg/m3 7820 7800 7770 7740 7700 7660        
Thermal conductivity coefficient W/(m — °C)   46 44 42 42 39 37 36 32  
Electrical resistivity (p, nominal value — m) 230                  
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) 11.6 12.5 13.2 13.8 14.3          
Specific heat capacity (C, J/(kg -°C)) 462