Steel 20G
Description
Steel 20G
Steel 20G: 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 20G.
General information of steel 20G
| Substitute brand |
| steel: 20, 30G. |
| Delivery type |
| long products, including shaped: GOST 4543−71, GOST 2590−71, GOST 2591−71, GOST 10702−78. Calibrated bar GOST 4543−71, GOST 7417−75, GOST 8559−75, GOST 8560−78, GOST 10702−78, GOST 1051−73. Polished bar and silver bar GOST 4543−71, GOST 14955−77. 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 |
| after improvement — critical rivets; after carburizing or cyanidation — piston pins, friction discs, spring pins, cam rollers, bolts, nuts, gears, worms and other parts with high surface hardness and wear resistance; without heat treatment — welded sub-motor frames, shoes, kerchiefs. |
Chemical composition of steel 20G
| 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) |
0.17−0.24 |
| Phosphorus (P), no more |
0.035 |
| Chromium (Cr), no more |
0.30 |
Mechanical properties of steel 20G
| Heat treatment, delivery condition |
Section, mm |
σ 0.2, MPa |
σ B, MPa |
δ 5 ,% |
ψ,% |
HB |
HRC e |
| Bar. Normalization 880 ° C, air. |
25 |
275 |
450 |
24 |
50 |
|
|
| Bar. Normalization 900 ° C, air. Vacation 610 ° С, air. |
650 |
235 |
430 |
24 |
|
126−163 |
|
| Cementation 900−920 ° C, air. Hardening 780−800 ° С, oil. Vacation 180−200 ° C, air. |
|
325−370 |
540−590 |
sixteen |
40 |
146−163 |
57−63 |
Mechanical properties depending on the tempering temperature
| vacation t, ° С |
σ 0.2, MPa |
σ B, MPa |
δ 10 ,% |
ψ,% |
KCU, J / m 2 |
| Hardening 890 ° C, water. Vacation 400−600 ° C, oil. |
| 400 |
920 |
980 |
6 |
67 |
59 |
| 500 |
700 |
780 |
12 |
74 |
128 |
| 600 |
540 |
640 |
fifteen |
79 |
127 |
Mechanical properties depending on the section
| Section, mm |
σ 0.2, MPa |
σ B, MPa |
δ,% |
ψ,% |
KCU, J / m 2 |
| Hardening 890 ° C, water. Vacation 450 ° C, oil. |
| 20 |
390 |
450 |
8 |
67 |
103 |
| 40 |
300 |
360 |
12 |
74 |
108 |
| 60 |
210 |
270 |
sixteen |
78 |
122 |
Technological properties of steel 20G
| Forging temperature |
| Beginning 1260, end 750. Section up to 600 mm, annealing with recrystallization (or normalization), one supercooling, tempering. |
| Weldability |
| welded without restrictions (except for chemically-thermally treated parts). Welding methods: RDS, ADS submerged arc and gas shielded, KTS without restrictions. |
| Machinability by cutting |
| In the normalized state at HB 143−187 K υ tv.spl. = 1.00, K υ b.st. = 0.95. |
| Tendency to release ability |
| not inclined |
| Flock sensitivity |
| not sensitive |
Temperature of critical points of steel 20G
| Critical point |
° C |
| Ac1 |
723 |
| Ac3 |
830 |
| Ar3 |
830 |
| Ar1 |
680 |
| Mn |
420 |
Impact strength of steel 20G
Impact strength, KCU, J / cm 2
| Delivery status, heat treatment |
+20 |
0 |
-20 |
-40 |
-60 |
| Tempering 890 C, water. Vacation 650 S. |
169 |
139 |
139 |
122 |
113−118 |
| Normalized and hot rolled sheet (GOST 1577−81) |
|
|
St. 29 |
|
|
Endurance limit of steel 20G
| σ -1, MPa |
σ B, MPa |
σ 0.2, MPa |
| 230 |
450 |
270 |
Hardenability of steel 20G
| Distance from the end, mm / HRC e |
| |
| |
| Heat treatment |
Crit. Diam. in water, mm |
Crete. hardness, HRCэ |
| Quenching 900 C, water. |
8 |
38 |
Physical properties of steel 20G
| Test temperature, ° С |
20 |
100 |
200 |
300 |
400 |
500 |
600 |
700 |
800 |
900 |
| Normal elastic modulus, E, GPa |
204 |
|
|
|
|
|
|
|
|
|
| Density of steel, pn, kg / m 3 |
7820 |
|
|
|
|
|
|
|
|
|
| Thermal conductivity coefficient W / (m ° С) |
|
78 |
67 |
48 |
|
|
|
|
|
|
| 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) |
12.5 |
13.4 |
14.4 |
15.1 |
|
15.2 |
|
|
|
|
| Specific heat (C, J / (kg ° C)) |
|
525 |
|
554 |
|
689 |
|
|
|
|
