|Designation GOST Cyrillic||18ХН3МА|
|Designation GOST Latin||18XH3MA|
|By chemical elements||18CrН3Mo|
18ХН3МА steel is used: for the production of hot rolled bars used for the manufacture of paws and cutter drill bits all sizes with air purge, as well as bits from 151 mm and less, borgonovo by hot forming; drill bits with a diameter of 320 mm or more.
Temperature range of use of steel from -70 °C to +450 °C.
|Bars and shapes||В32||TU 3-26-79, TU 3-27-79, TU 3-850-80, TU 3-938-79|
According to TU 3-26-79 the chemical composition is given for steel grade 18HN3MA-VD.
According to TU 3-850-80 the chemical composition is given for steel grade 18HN3MA. The presence of residual titanium in the steel to 0.030%, tungsten to 0.20% and vanadium to 0.050% is not a defect.
|Section, mm||sT|s0,2, MPa||σU, MPa||d5, %||y, %||KCU, kJ/m2|
|Bars hot rolled as supplied on the other 3-850-80. 1-I'm quenching in oil from 890±15 °C + 2 quenching in oil from 775±15 °C + Vacation at 170-220 °C, air cooling (longitudinal samples)|
Description mechanical marks
|sT|s0,2||Yield strength or limit of proportionality with a tolerance for residual deformation of 0.2%|
|σU||Limit short-term strength|
|d5||Elongation after rupture|
|y||The relative narrowing|
|Temperature||r, kg/m3||a, 10-6 1/°C||l, W/(m · °C)|
A description of the physical symbols
|Е||The normal elasticity modulus|
|l||Coefficient of thermal conductivity|
|R||UD. the resistivity|
|Macrostructure and pollution||Macrostructure of steel ready rods on the other 3-850-80 checked for breaks and pickled Templeton, must meet the requirements of GOST 4543 and should not have shrinkage, porosity, bubbles, cracks, delamination, inclusions and placenow. Upon detection placenow steel is rejected. Evaluation of the macrostructure of the etched on Templeton is on scales GOST 10243. Permitted: Central porosity; a point inhomogeneity; phase separation squared, General, regional and Pousada liquation not more than 2 points; layer-by-layer crystallization and the light circuit is not more than 3 points. Not allowed subcortical bubbles and intergranular cracks. Steel is controlled on the contamination of non-metallic inclusions, the content of which is determined according to GOST 1778 for 6 samples and should not exceed the contents in points (average/maximum): - FROM Point - 2,0/4,0; - Stroke OS - 3,0/4,0; - Fragile CX - 3,5/4,0; Plastic SP 2,5/4,0; - non-deformable SN - 2,5/4,0; - Sulfides C - 2,5/4,0; Nitrides N - 1,5/2,5.|
|Microstructure||The microstructure of the initial sample of steel 18ХН3МА-W is a coarse-grained pearlitic-ferritic structure with dispersed inclusions of the alloying elements. After the gas carburizing and hardening with following tempering forms a fine-grained martensitic structure. After electrolytic-plasma treatment the microstructure of steel 18ХН3МА-sh has a fine-grained martensitic-bantou structure. Under cyclic heating a highly concentrated plasma energy, the transformation of pearlite into austenite. The austenitic grain size shall be not larger than the number 5 according to GOST 5639.|
|Particularities of production of goods||Bars hot rolled on the other 3-850-80 are supplied in heat-treated (annealed or vysokoopasnye) with hardness not exceeding 269 HB (indentation diameter not less than 3.7 mm). Hardenability of steel (after normalization at 920±10 °C or quenching from 890±10 °C) - Hardness HRC should be at a distance of 4.5 mm from the end of 37.5÷43,5, and at a distance of 30 mm from the end - 25÷35.|