Cast iron ЧНМ1,2

Designation

Name The value
Designation GOST Cyrillic ЧНМ1,2
Designation GOST Latin ChHM1,2
Transliteration ChNM12
By 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 (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 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 properties

σU, MPa HB, MPa
Castings on OST 1 90077-72
≥275 240-320

Description mechanical marks

Name Description
σU Limit short-term strength
HB Brinell hardness number

Technological properties

Name The value
Macrostructure and pollution 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).