Steel 45G2
	
	
	Description
	Steel 45G2
Steel 45G2: 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 45G2.
General information of steel 45G2
| Substitute brand | 
| steel 50G2 | 
| Delivery type | 
| long products, including shaped: GOST 4543−71, GOST 2590−71, GOST 2591−71, GOST 2879−69. Calibrated bar GOST 4543−71, GOST 7417−75, GOST 8559−75, GOST 8560−78, GOST 1051−73. Polished bar and silver bar GOST 14955−77. | 
| Application | 
| gear shafts, crankshafts and cardan shafts, half-shafts, worms, connecting rod caps, connecting rods, links of conveyor chains and other large-sized medium-loaded parts. | 
Chemical composition of steel 45G2
| Chemical element | % | 
| Silicon (Si) | 0.17−0.37 | 
| Manganese (Mn) | 1.40−1.80 | 
| Copper (Cu), no more | 0.30 | 
| Nickel (Ni), no more | 0.30 | 
| Sulfur (S), no more | 0.035 | 
| Carbon (C) | 0.41−0.49 | 
| Phosphorus (P), no more | 0.035 | 
| Chromium (Cr), no more | 0.30 | 
Mechanical properties of 45G2 steel
| Fur. properties | 
| Fur. properties at elevated temperatures | 
| Fur. properties depending on tempering temperature | 
Mechanical properties
| Heat treatment, delivery condition | Section, mm | σ 0.2, MPa | σ B, MPa | δ 5 ,% | ψ,% | HB | 
| Bar. Hardening 850 ° C, low. Vacation 650 ° C, air. | 25 | 400 | 680 | eleven | 40 |  | 
| Annealing: heating up to 780 ° С at a rate of 350 deg / h, holding, cooling with a furnace at a speed of 40 deg / h |  | 350 | 670 | 21 | 44 | 187 | 
| Normalization 810 ° C, air. |  | 480 | 800 | eighteen | 51 | 241 | 
Mechanical properties at elevated temperatures
| test t, ° C | σ 0.2, MPa | σ B, MPa | δ 5 ,% | ψ,% | 
| Sample 10 mm in diameter and 50 mm in length, rolled and annealed | 
| 800 | 97 | 115 | 35 | 98 | 
| 900 | 55 | 74 | 54 | 98 | 
| 1000 | 35 | 49 | 59 | 100 | 
| 1100 | 27 | 35 | 63 | 100 | 
| 1200 | 17 | 26 | 73 | 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 | HB | 
| A bar with a section of 25 mm. Hardening 810 ° С, oil. Cooling after tempering in oil. | 
| 375 |  | 1390 | 7 | 42 | ten | 418 | 
| 450 |  | 1200 | 8 | 42 | 19 | 340 | 
| 525 |  | 1040 | thirteen | 47 | 29 | 302 | 
| 600 | 810 | 920 | fifteen | 54 | 49 | 269 | 
| A bar with a cross section of 70 mm. Hardening 820 ° C, water. | 
| 300 | 1180 | 1500 | 6 | sixteen | 29 |  | 
| 400 | 900 | 1180 | nine | 34 | 39 |  | 
| 500 | 740 | 970 | thirteen | 49 | 78 |  | 
| 600 | 640 | 810 | eleven | 60 | 147 |  | 
| A bar with a cross section of 35 mm. Hardening 850 ° С, oil. | 
| 300 | 1290 | 1520 | five | ten | ten |  | 
| 400 | 1080 | 1270 | 6 | sixteen | ten |  | 
| 500 | 730 | 1030 | eleven | 39 | 78 |  | 
| 600 | 670 | 860 | eighteen | 52 | 166 |  | 
| A bar with a cross section of 70 mm. Hardening 850 ° С, oil. | 
| 300 | 610 | 1010 | 17 | 47 | 49 |  | 
| 400 | 640 | 980 | 17 | 47 | 73 |  | 
| 500 | 630 | 920 | eighteen | 50 | 88 |  | 
| 600 | 540 | 820 | 20 | 55 | 98 |  | 
Technological properties of steel 45G2
| Forging temperature | 
| The beginning is 1200, the end is 750−800. Sections up to 100 mm are cooled in air, sections 101−300 mm — in a mold. | 
| Weldability | 
| RDS — heating and subsequent heat treatment are required. KTS — subsequent heat treatment is required. | 
| Machinability by cutting | 
| After normalization at HB 229 K υ tv.spl. = 0.80, K υ b.st. = 0.55. | 
| Tendency to release ability | 
| inclined | 
| Flock sensitivity | 
| insensitive | 
Temperature of critical points of steel 45G2
| Critical point | ° C | 
| Ac1 | 711 | 
| Ac3 | 765 | 
| Ar3 | 704 | 
| Ar1 | 626 | 
| Mn | 245 | 
Impact strength of steel 45G2
Impact strength, KCU, J / cm 2
| Delivery status, heat treatment | +20 | -20 | -40 | 
| Normalization |  | 59 |  | 
| Ingot. Quenching with high tempering. HB 228−235. Longitudinal specimen | 186 | 176 | 157 | 
| Ingot. Quenching with high tempering. HB 228−235. Cross pattern | 24 | 29 | 24 | 
Endurance limit of 45G2 steel
| σ -1, MPa | σ B, MPa | σ 0.2, MPa | Heat treatment, steel condition | 
| 598 | 1200 | 1070 |  | 
| 686 | 1570 |  | HB 570 | 
| 382 | 900 | 550 | HB 248 | 
Hardenability of steel 45G2
Hardening 840 C. Hardness for strips of hardenability HRCe.
| Distance from the end, mm / HRC e | 
| 1.5 | 3 | 4.5 | 6 | nine | 12 | fifteen | eighteen | 21 | 27 | 
| 54−61 | 52−60.5 | 50−60 | 48.5−59 | 41.5−58 | 34.5−55 | 29−52.5 | 27−48 | 25.5−45.5 | 23−41.5 | 
| Amount of martensite,% | Crit. Diam. in water, mm | Crit. Diam. in oil, mm | Crete. hardness, HRCэ | 
| 50 | 43−85 | 20−55 | 44−49 | 
| 90 | 23−64 | 6−38 | 51−55 | 
Physical properties of steel 45G2
| Test temperature, ° С | 20 | 100 | 200 | 300 | 400 | 500 | 600 | 700 | 800 | 900 | 
| Normal elastic modulus, E, GPa | 204 |  |  |  |  |  |  |  |  |  | 
| Torsional shear elastic modulus G, GPa | 83 |  |  |  |  |  |  |  |  |  | 
| Density of steel, pn, kg / m 3 | 7810 |  |  |  |  |  |  |  |  |  | 
| Thermal conductivity coefficient W / (m ° С) |  |  | 45 | 43 | 41 | 35 |  |  |  |  | 
| 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) | 11.3 | 11.9 | 12.7 |  | 14.7 |  |  |  |  |  | 
| Specific heat (C, J / (kg ° C)) |  | 445 | 428 |  |  |  |  |  |  |  |