Steel 20HML
Designation
| Name |
The value |
| Designation GOST Cyrillic |
20ХМЛ |
| Designation GOST Latin |
20XML |
| Transliteration |
20HML |
| The chemical elements |
20CrMo |
Description
20HML steel is used: for the manufacture of castings, gears, joints, bushings, gear wheels, cylinders, clips and other parts operating for a long period of time at temperatures up to +500 °C; casting parts for gas turbines and axial compressors operating at temperatures up to +510 °C; casting groups 1, 2, 3 parts of valves and actuators to it, working in non-aggressive environments at temperatures from -40 to +540 °C without restriction of the nominal working pressure; castings of body parts, shipbuilding, operating at temperatures of 400−500 °C; stationary parts of steam turbines operating at temperatures up to +520 °C; casting equipment parts (valves) for nuclear power stations, heat supply stations, heat and power plants, experimental and research nuclear reactors and installations.
Note
Heat-resistant steel pearlitic class.
Standards
| Name |
Code |
Standards |
| Castings, steel |
В82 |
GOST 977-88, OST 108.961.04-80, OST 26-07-402-83, OST 5Р.9285-95, TU 26-02-19-75, TU 4112-091-00220302-2006, ST ЦКБА 014-2004, TU 5.961-11151-92 |
| Castings with special properties (cast iron and steel) |
В83 |
OST 108.961.02-79, OST 108.961.03-79 |
| Welding and cutting of metals. Soldering, riveting |
В05 |
RTM 108.020.122-78 |
Chemical composition
| Standard |
C |
S |
P |
Mn |
Cr |
Si |
Ni |
Fe |
Cu |
Mo |
| OST 108.961.03-79 |
0.15-0.22 |
≤0.025 |
≤0.025 |
0.5-0.8 |
0.5-0.8 |
0.2-0.45 |
≤0.3 |
The rest |
≤0.3 |
0.4-0.6 |
| TU 5.961-11151-92 |
0.15-0.25 |
≤0.04 |
≤0.04 |
0.4-0.9 |
0.4-0.7 |
0.2-0.42 |
- |
The rest |
- |
0.4-0.6 |
| OST 108.961.02-79 |
0.15-0.25 |
≤0.025 |
≤0.025 |
0.5-0.8 |
0.5-0.8 |
0.2-0.45 |
≤0.3 |
The rest |
≤0.3 |
0.4-0.6 |
| OST 5Р.9285-95 |
0.15-0.25 |
≤0.04 |
≤0.04 |
0.4-0.9 |
0.4-0.7 |
0.2-0.42 |
≤0.3 |
The rest |
≤0.3 |
0.4-0.6 |
Fe is the basis.
According to OST 108.961.04-80, the total sulfur and phosphorus content should be ≤ 0.050% for all possible tolerances.
According to OST 5R.9285-95, the content of nickel to 0.50% and copper to 0.40% is not a defect condition provided that the requirements of the standard are observed and if there are no special instructions in the technical conditions of the order or drawing.
According to TU 5.961-11151-92 for castings of grades 1 and 2 the mass fraction of cobalt in steel should not exceed 0.20%, and for castings in the direct irradiation zone - 0.15%.
Mechanical characteristics
| Section, mm |
sT|s0,2, MPa |
σB, MPa |
d |
y, % |
kJ/m2, кДж/м2 |
Brinell hardness number, MPa |
| Normalization with 880-890 °C + Vacation at 600-650 °C, air cooling |
| 100 |
≥245 |
≥441 |
≥18 |
≥30 |
≥294 |
- |
| Normalization at 890-910 °C (extract 8 hours) + Vacation at 640-660 °C (exposure 8 h), cooling to 300 °C at a speed of 40-50 °C/h. |
| - |
305-390 |
470-550 |
12-28 |
27-66 |
- |
- |
| Casting without heat treatment |
|
365-570 |
540-670 |
6-16 |
15-24 |
100-340 |
- |
| Normalization at 890-910 °C (extract 8 hours) + Vacation at 640-660 °C (exposure 8 h), cooling to 300 °C at a speed of 40-50 °C/h. |
| - |
345 |
430 |
17-21 |
59-62 |
- |
- |
| Casting parts of gas turbines. Normalization when 880-910 °C, air cooling + Vacation at 620-650 °C, cooling with the furnace to 300 °C, air cooling |
| - |
≥245 |
≥461 |
≥18 |
≥30 |
≥290 |
135-180 |
| Normalization at 890-910 °C (extract 8 hours) + Vacation at 640-660 °C (exposure 8 h), cooling to 300 °C at a speed of 40-50 °C/h. |
| - |
295 |
380 |
22 |
69-75 |
- |
- |
| Casting parts, cylinders, clips stationary steam turbines. Normalization at 880-900 °C + Vacation at 600-650 °C, air cooling |
| - |
≥250 |
≥470 |
≥18 |
≥30 |
≥294 |
135-180 |
| Normalization at 890-910 °C (extract 8 hours) + Vacation at 640-660 °C (exposure 8 h), cooling to 300 °C at a speed of 40-50 °C/h. |
| - |
195-235 |
290 |
28 |
82 |
- |
- |
| Castings for shipbuilding. When normalizing 890-920 °C + vacation at 630-670 °C, air cooling |
| - |
≥250 |
≥450 |
≥18 |
≥30 |
≥300 |
135-180 |
| Annealing at 880-900 °With (extract 8 hours) |
| - |
365 |
460 |
17-22 |
41-51 |
- |
- |
| - |
295-325 |
390-410 |
14-24 |
64-79 |
- |
- |
| - |
245-265 |
305-345 |
24-26 |
73 |
- |
- |
| Castings with wall thickness up to 100 mm in the delivery state on the other 5.961-11151-92. Normalization at 880-920 °C + Vacation at 600-650 °C. the Critical temperature of brittleness of TKO ≤ 50 °C. |
| - |
≥245 |
≥441 |
≥18 |
≥30 |
≥490 |
- |
| - |
≥230 |
≥430 |
- |
≥35 |
- |
- |
| - |
≥220 |
≥420 |
- |
≥52 |
- |
- |
| - |
≥200 |
≥400 |
- |
≥55 |
- |
- |
Description mechanical marks
| Name |
Description |
| Section |
Section |
| sT|s0,2 |
Yield strength or limit of proportionality with a tolerance for residual deformation of 0.2% |
| σB |
Limit short-term strength |
| d |
Elongation after rupture |
| y |
The relative narrowing |
| kJ/m2 |
Toughness |
Physical characteristics
| Temperature |
r, кг/м3 |
a, 10-6 1/°С |
| 0 |
7800 |
- |
| 20 |
7800 |
- |
| 100 |
7780 |
109 |
| 200 |
7750 |
124 |
| 300 |
7720 |
128 |
| 400 |
7690 |
131 |
| 500 |
7650 |
136 |
| 600 |
7620 |
136 |
| 800 |
- |
139 |
A description of the physical symbols
| Name |
Description |
| Е |
The normal elasticity modulus |
| r |
Density |
| l |
Coefficient of thermal conductivity |
| С |
Specific heat |
Technological properties
| Name |
The value |
| Weldability |
Limited weldability. The welding process - SMAW. When welding requires preheating. After welding and repair of defects by welding is used vacation at 600-650 °C. |
| Propensity to temper brittleness |
Tend not. |
| Workability by cutting |
In the normalized and tempered condition at NV 135-180 and blower SB=460 MPa Kn b.St.=0,85. |
| Defect welding |
Welding defects of castings after cutting is carried out with preliminary and attendant heating up to 350-400 °C. for semi-automatic welding in carbon dioxide environment used wire SV-08ХГСМФА with a diameter of 2 mm at a current of 300-350 A. Welding defects by manual welding is done with electrodes ЦЛ45. When heat treated after welding defects to cool in the oven to 100-150 °C at a rate of 30-50 °C/h and further in the air. |
