Steel 40G
	
	
	Description
	Steel 40G
Steel 40G: 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 brand — Steel 40G.
General information of steel 40G
| Substitute brand | 
| steel: 45, 40X. | 
| Delivery type | 
| long products, including shaped: GOST 4543−71, GOST 2590−71, GOST 2591−71, GOST 2879−69, GOST 10702−78. Calibrated bar GOST 4543−71, GOST 7417−75, GOST 8559−75, GOST 8560−78, GOST 10702−78. Polished bar and silver bar GOST 4543−71, GOST 14955−77, GOST 10702−78. Thick sheet GOST 1577−81, GOST 19903−74. Strip GOST 103−76, GOST 82−70. Forgings and forged billets GOST 1133−71, GOST 4543−71. | 
| Application | 
| axles, crankshafts, gears, rods, tires, fittings, connecting rods, sprockets, camshafts, plunger heads and other parts that require increased strength. | 
Chemical composition of steel 40G
| Chemical element | % | 
| Silicon (Si) | 0.17−0.37 | 
| Manganese (Mn) | 0.70−1.00 | 
| Copper (Cu), no more | 0.30 | 
| Nickel (Ni), no more | 0.30 | 
| Sulfur (S), no more | 0.035 | 
| Carbon (C) | 0.37−0.45 | 
| Phosphorus (P), no more | 0.035 | 
| Chromium (Cr), no more | 0.30 | 
Mechanical properties of steel 40G
Mechanical properties
| Heat treatment, delivery condition | Section, mm | σ 0.2, MPa | σ B, MPa | δ 5 ,% | ψ,% | KCU, J / m 2 | 
| Bar. Hardening 860 ° C, water. Vacation 600 ° C, air. | 25 | 350 | 590 | 17 | 45 | 59 | 
| Hardening 830−850 ° С, water. Vacation 180−200 ° C, air. |  |  |  |  |  |  | 
Mechanical properties depending on the tempering temperature
| vacation t, ° С | σ 0.2, MPa | σ B, MPa | δ 5 ,% | ψ,% | KCU, J / m 2 | 
| A bar with a cross section of 35 mm. Hardening 800 ° C, water. | 
| 300 | 860 | 1120 | ten | thirty | 39 | 
| 400 | 780 | 1010 | ten | 43 | 59 | 
| 500 | 680 | 880 | fifteen | 54 | 108 | 
| 600 | 530 | 740 | 20 | 63 | 137 | 
| 700 | 430 | 630 | 35 | 70 | 157 | 
| A bar with a cross section of 35 mm. Hardening 850 ° С, oil. | 
| 300 | 570 | 760 | fourteen | 50 | 68 | 
| 400 | 550 | 760 | sixteen | 51 | 73 | 
| 500 | 510 | 720 | eighteen | 51 | 73 | 
| 600 | 440 | 680 | 22 | 55 | 98 | 
| 700 | 320 | 580 | thirty | 66 | 78 | 
| A bar with a cross section of 70 mm. Hardening 800 ° C, water | 
| 300 | 580 | 880 | fourteen | 46 | 39 | 
| 400 | 570 | 850 | fifteen | 47 | 39 | 
| 500 | 540 | 790 | 19 | 55 | 93 | 
| 600 | 500 | 730 | 23 | 60 | 157 | 
| 700 | 430 | 620 | 27 | 70 | 137 | 
| A bar with a cross section of 70 mm. Hardening 850 ° C, oil | 
| 300 | 570 | 840 | fifteen | 48 | 59 | 
| 400 | 550 | 800 | 17 | 49 | 68 | 
| 500 | 510 | 780 | eighteen | 50 | 68 | 
| 600 | 440 | 680 | 24 | 55 | 98 | 
| 700 | 390 | 590 | thirty | 66 | 117 | 
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 | 
| Hardening 840 ° C, water. Vacation 550 ° C, air. | 
| Sample cutting location — center | 50 | 570 | 820 | 20 | 49 | 88 | 
| Sample cutting location — edge | 50 | 590 | 820 | 20 | 51 | 88 | 
| Sample cutting location — center | 100 | 490 | 790 | 22 | 50 | 68 | 
| Sample cutting location — edge | 100 | 540 | 810 | 19 | 53 | 68 | 
| Sample cutting location — center | 200 | 480 | 760 | 24 | 50 | 59 | 
| Sample cutting location — edge | 200 | 530 | 790 | fifteen | 52 | 68 | 
Technological properties of steel 40G
| Forging temperature | 
| Beginning 1250, end 800. Billets with a cross section up to 400 mm are cooled in air. | 
| Weldability | 
| restrictedly weldable. Welding methods: RDS, ADS submerged arc. Heating and subsequent heat treatment is recommended. KTS without restrictions. | 
| Machinability by cutting | 
| In the normalized state at HB 174−207 K υ tv.spl. = 0.95, K υ b.st. = 0.70. | 
| Tendency to release ability | 
| inclined | 
| Flock sensitivity | 
| insensitive | 
Temperature of critical points of steel 40G
| Critical point | ° C | 
| Ac1 | 723 | 
| Ac3 | 785 | 
| Ar3 | 770 | 
| Ar1 | 680 | 
Impact strength of steel 40G
Impact strength, KCU, J / cm 2
| Delivery status, heat treatment | +20 | -20 | -40 | -60 | 
| Hot rolled condition | 69 | 70 | 53 | 29 | 
| Annealing | 44 | ten | 7 |  | 
| Quenching, tempering | 173 | 137 | 117 | 82 | 
Endurance limit of steel 40G
| σ -1, MPa | σ B, MPa | σ 0.2, MPa | Heat treatment, steel condition | 
| 515 | 1160 | 1120 | Hardening 800 C, water. Vacation 380 C, 1 hour, air. | 
| 402 | 890 | 790 | Hardening 800 C, water. Vacation 515 C, 1h, air. | 
| 367 | 790 | 660 | Hardening 800 C, water. Vacation 570 C, 1 hour, air. | 
| 328 | 710 | 630 | Hardening 800 C, water. Vacation 650 C, 1h, air. | 
Hardenability of steel 40G
Hardening 840 C. Hardness for strips of hardenability HRCe.
| Distance from the end, mm / HRC e | 
| 1.5 | 3 | 4.5 | 6 | 7.5 | nine | 12 | fifteen | eighteen | 
| 50.5−59 | 47.5−57.5 | 41.5−54 | 32−49.5 | 27−41.5 | 24−35 | 20.5−29.5 | 27.5 | 26 | 
| Amount of martensite,% | Crit. Diam. in water, mm | Crit. Diam. in oil, mm | Crete. hardness, HRCэ | 
| 50 | 23−27 | 6−14 | 43−46 | 
| 90 | 15−23 | 4−6 | 48−53 | 
Physical properties of steel 40G
| Test temperature, ° С | 20 | 100 | 200 | 300 | 400 | 500 | 600 | 700 | 800 | 900 | 
| Normal elastic modulus, E, GPa | 200 |  |  |  |  |  |  |  |  |  | 
| Density of steel, pn, kg / m 3 | 7810 |  |  |  |  |  |  |  |  |  | 
| Thermal conductivity coefficient W / (m ° С) |  | 60 | 53 |  | 47 | 24 |  |  |  |  | 
| 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) | 11.1 | 11.7 | 12.7 |  | 14.3 |  |  |  |  |  | 
| Specific heat (C, J / (kg ° C)) | 487 | 483 |  | 491 |  | 575 |  |  |  |  |