Steel 12KH2NVFA (ЭИ712)
|Designation GOST Cyrillic||12Х2НВФА|
|Designation GOST Latin||12X2HBFA|
|By chemical elements||12Cr2НWV|
|Designation GOST Cyrillic||ЭИ712|
|Designation GOST Latin||EI712|
|By chemical elements||-|
12KH2NVFA steel is used: for the manufacture of welded assemblies and structures, not subjected to heat treatment after welding (including off), which require increased strength; loaded welded parts; solid-rolled rings for different purposes; the spars of the car.
Alloy structural steel high quality with low carbon content.
Steel can be used for carburized parts operating at temperatures of 230−250 °C; and nesvorny welded parts operating at temperatures up to +500 °C.
|Sheets and strips||В33||GOST 11268-76, GOST 11269-76|
|Steel pipes and fittings to them||В62||GOST 21729-76, TU 14-3-967-80, TU 14-3-463-2005, TU 14-3-975-80|
|Sheets and strips||В23||GOST 82-70|
|Classification, nomenclature and General rules||В20||OST 1 90005-91|
|Blanks. Of the workpiece. Slabs||В31||OST 1 90280-79, TU 1-92-156-90, TU 14-1-1278-75|
|Bars and shapes||В32||OST 1 92049-76, TU 14-1-1885-85, TU 14-1-2854-79, TU 14-1-950-74, TU 14-1-3238-81, TU 14-1-3238-2006, TU 14-1-1271-75|
|Bars and shapes||В22||TU 14-2-490-82|
According to TU 14-1-3238-81 the chemical composition is given for steel grade 12Х2НВФА. For steel grade 12Х2НВФА-СШ the content S≤0,015%.
According to TU 14-1-1885-85 the chemical composition is given for steel grade 12Х2НВФА-ВД (ЭИ712-ВД). The presence of molybdenum up to 0.15%, titanium up to 0.030% is not a defective feature. Partial replacement of tungsten with residual molybdenum is allowed in the steel at the rate: one part by weight of molybdenum replaces three parts by weight of tungsten, while the content of tungsten in steel should be at least 0.60%. The allowable variation in manganese content in steel is ± 0.010%.
|Section, mm||sT|s0,2, MPa||σU, MPa||d5, %||y, %||KCU, kJ/m2||HB, MPa||HRC|
|Pipe seamless cold drawn, cold rolled and toplocatie, heat-treated in the delivery condition according to GOST 21729-76|
|Gradation of performance properties of the finished heat-treated parts for OST 1 90005-91|
|Ring forged in OST 1 92049-76. Quenching in oil with 895-925 °C + Vacation at 500-550 °C, air cooling|
|Steel hot-rolled sheet (4-60 mm) 4-th and 5-th categories. Quenching in oil with 910±15 °C + Vacation at 490-550 °C, air cooling|
|Bars and strip hot rolled and forged. Quenching in oil with 895-925 °C + Vacation at 500-550 °C, air cooling|
|Rods made of steel 12KH2NVFA (ЭИ712) TU 14-1-1885-85. Quenching in oil with 895-925 °C + Vacation at 480-510 °C, air cooling. In the graph KCU KCU values are shown along the fiber/KCU across the grain|
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|
|HB||Brinell hardness number|
|HRC||Rockwell hardness (indenter diamond spheroconical)|
|Weldability||Well weldable manual arc, contact and agrono-arc (manual and automatic) welding; satisfactory — and atomic-hydrogen gas welding.|
|Macrostructure and pollution||Macrostructure of steel when testing for the breaks in the longitudinal direction and transverse templeto selected from rolled, should not have shrinkage, porosity, bubbles, cracks, delamination, inclusions and placenow and defects of fracture, listed in Annex 3 GOST 10243. The Central porosity, point heterogeneity and phase separation in the square should not exceed 1 points; layer-by-layer crystallization and the bright loop - 3 points reference scales GOST 10243. All other defects under GOST 10243, are not allowed. Pollution steel non-metallic inclusions should be according to the average score is not higher (in points): oxides of point 1,5, 2,0 stroke oxides, silicates fragile 1,0, 1,0 silicates plastic, silicates, non-deformed 2,5, 2,5 sulfides, nitrides stroke and point 1,0.|
|Features of heat treatment||Steel 12KH2NVFA strengthen by heat treatment (quenching in oil with subsequent tempering or normalizing with tempering).|