Cast iron ЧНМ1,2
Designation
| Name |
The value |
| Designation GOST Cyrillic |
ЧНМ1,2 |
| Designation GOST Latin |
ChHM1,2 |
| Transliteration |
ChNM12 |
| The chemical elements |
ZrНMo1,2 |
Description
Cast iron ЧНМ1,2 applies: for the production of castings for aircraft.
Note
Modified heat-resistant grey iron.
Standards
| Name |
Code |
Standards |
| Castings with special properties (cast iron and steel) |
В83 |
OST 1 90077-72 |
Chemical composition
| Standard |
C |
S |
P |
Mn |
Cr |
Si |
Ni |
Fe |
Mo |
| OST 1 90077-72 |
3-3.5 |
≤0.1 |
≤0.3 |
0.6-0.9 |
≤0.4 |
1.7-2.4 |
1.5-2.2 |
The rest |
0.8-1.5 |
Fe is the basis.
According to OST 1 90077-72, with the following mechanical properties and microstructure satisfactory, the following deviations in chemical composition are acceptable: for carbon ± 0.10%, for chromium, silicon, molybdenum, nickel and copper + 0.2% for each.
Mechanical characteristics
| σB, MPa |
Brinell hardness number, MPa |
| Castings on OST 1 90077-72 |
| ≥275 |
240-320 |
Description mechanical marks
| Name |
Description |
| σB |
Limit short-term strength |
Technological properties
| Name |
The value |
| Macrostructure and contamination |
The appearance of the fracture of castings on OST 1 90077-72 should be dense, fine-grained, light-gray, with no signs of chill. Surface of castings shall be cleaned of sand and metal penetration. Sprues, heaving, bays, growths and veining must be cut or polished by abrasive material in the tolerances on the drawing. Nikitina, crack and end-to-end sinks are not allowed. |
| Microstructure |
According to OST 1 90077-72 microstructure of castings after aging should consist of pearlite and acicular sorbitol, graphite, small plate and scatter and separate inclusions of complex phosphide-carbide eutectic. |
| Features of heat treatment |
According to OST 1 90077-72 castings of modified cast iron are subjected to natural or artificial aging consisting of heat treatment at a temperature of 550-600°C for 3,0-4,0 hours (depending on wall thickness of casting). |
