Steel 25Х2НМФ (25Х2НМФА)
Designation
| Name |
The value |
| Designation GOST Cyrillic |
25Х2НМФ |
| Designation GOST Latin |
25X2HMF |
| Transliteration |
25H2NMF |
| The chemical elements |
25Cr2НMoV |
| Name |
The value |
| Designation GOST Cyrillic |
25Х2НМФА |
| Designation GOST Latin |
25X2HMFA |
| Transliteration |
25H2NMFA |
| The chemical elements |
25Cr2НMoV |
Description
25Х2НМФ steel is used: for the manufacture of forgings for welded rotors for turbines K-1000−60/1500 and its modifications (To-1000−60/1500−2 etc.), forgings without machining of the disk blank, blanks shanks and medium-sized parts. Procurement of welded rotors are blanks with individual determination of mechanical properties and application of special methods of control.
Note
Structural steel high-quality romancelatina.
Standards
| Name |
Code |
Standards |
| Bulls. Blanks. Slabs |
В31 |
TU 05764417-051-96, TU 108.1082-82 |
Chemical composition
| Standard |
C |
S |
P |
Mn |
Cr |
Si |
Ni |
Fe |
Cu |
V |
Mo |
| TU 108.1082-82 |
0.23-0.27 |
≤0.015 |
≤0.015 |
0.4-0.7 |
1.8-2.2 |
0.02-0.1 |
1.3-1.6 |
The rest |
≤0.25 |
0.05 |
0.4-0.6 |
Fe is the basis.
According to TU 108.1082-82, the chemical composition is given for steel grade 25Х2НМФА. Mass fraction of Vanadium (V) is indicated by calculation and chemical analysis is not determined. In the case of using blanks for the manufacture of turbines of the first circuit of nuclear power plants, it is necessary to determine the content of cobalt (Co) blanks in the metal, which should not be more than 0.025%. The following deviations of the content of elements in the ladle sample from the specified composition are allowed: carbon ± 0.010%, sulfur +0.0010%, phosphorus +0.0010%. The enterprise producing the final thermal and mechanical treatment shall additionally determine the content of carbon, silicon, sulfur and phosphorus in the sample metal taken from the blanks in the places indicated in the drawings. The permissible deviations in the content of carbon, sulfur and phosphorus must meet the above requirements. It is allowed to reduce the carbon content in the metal of blanks to 0.20%, provided that the values of the mechanical properties are consistent. The hydrogen content of the metal bars must not exceed 2.5 cm 3 / 100g. The results of determination of the vanadium content in the ladle sample are not acceptance tests, but are to be recorded in the blank sheets.
Mechanical characteristics
| Section, mm |
sT|s0,2, MPa |
σB, MPa |
d5, % |
y, % |
kJ/m2, кДж/м2 |
Brinell hardness number, MPa |
| Of the workpiece after final heat treatment in the state of delivery on the other 108.1082-82 |
|
520-687 |
≥657 |
≥14 |
≥40 |
≥590 |
≤270 |
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 |
| d5 |
Elongation after rupture |
| y |
The relative narrowing |
| kJ/m2 |
Toughness |
Technological properties
| Name |
The value |
| Macrostructure and contamination |
The macrostructure of the etched surface of the workpiece on the other 108.1082-82 should not have cracks, placenow, shrinkage porosity, cavities, sekulow, large non-metallic inclusions, clusters of small non-metallic inclusions and the location of inclusions in a chain. Non-metallic inclusions up to 1 mm inclusive shall not be considered unless they are part of clusters and chains. On polished and etched surfaces of workpieces indicated in the drawing, permitted disparate non-metallic inclusions up to 2 mm inclusive not more than 10 pieces, as well as inclusion size of 2 to 4 mm inclusive not more than 5 pieces. the Accumulation of non-metallic inclusions is considered to be a group of defects up to 1 mm, inclusive, in the amount of not less than 10 pieces with distance between them of not more than 5 times the length of the longest defect from among the members of the cluster. Large non-metallic inclusions are the inclusions larger than 2 mm. Chain non-metallic inclusions consider the inclusion of up to 2 mm in one line of at least 5 pieces with distance between them not exceeding three times the length of the longest defect in the chain. |
| Features of production |
The steel workpiece must be smelted in arc furnaces with basic treatment on the installation of the circulating degassing of steel (UCWS), followed by casting in a vacuum chamber or, for bars weighing up to 60 tons - in an atmosphere of inert gases. Casting ingots should be made in specialized molds. Smelting and casting, forging and preliminary heat treatment of workpieces, machining and final heat treatment must be carried out according to the agreed technology from zniitmash. |
| Features of heat treatment |
Temperature tempering of workpieces in the process of final heat treatment should not be below 630 °C. |
