Designation
| Name |
The value |
| Designation GOST Cyrillic |
70ХГФА |
| Designation GOST Latin |
70XGFA |
| Transliteration |
70HGFA |
| By chemical elements |
70CrMnV |
Description
70HGFA steel is used: for the production of wire rod and heat-treated wire diameter 1.2−5.5 mm, intended for the manufacture of springs; valve springs car engine.
Note
Chrome vanadium spring steel
Standards
| Name |
Code |
Standards |
| Steel wire medium and high carbon |
В72 |
GOST 1071-81, TU 14-4-1380-91 |
| Bars and shapes |
В32 |
TU 14-1-4104-86 |
| Blanks. Of the workpiece. Slabs |
В31 |
TU 14-134-326-93 |
Chemical composition
| Standard |
C |
S |
P |
Mn |
Cr |
Si |
Ni |
Fe |
Cu |
Al |
V |
| TU 14-134-326-93 |
0.65-0.72 |
≤0.015 |
≤0.015 |
0.5-0.8 |
0.3-0.5 |
0.15-0.3 |
≤0.15 |
Rest |
≤0.1 |
- |
0.1-0.2 |
| GOST 1071-81 |
0.65-0.72 |
≤0.025 |
≤0.025 |
0.5-0.8 |
0.3-0.5 |
0.15-0.3 |
≤0.2 |
Rest |
≤0.15 |
≤0.05 |
0.1-0.2 |
Fe is the basis.
According to GOST 1071-81 the chemical composition is given for steel grade 70HGFA.
According to TU 14-1-4104-86, TU 14-134-326-93 the chemical composition is given for steel grade 70HGFA-III. Deviations from the standards of chemical composition in finished rolled products are in accordance with GOST 14959, except copper. The deviation in content of copper in steel is no more than +0,020%.
Mechanical properties
| Section, mm |
σU, MPa |
| Rod in the supply position on the other 14-1-4104-86 |
| - |
≤1270 |
| The wire spring heat-treated in the delivery condition according to GOST 1071-81 |
| 1.2-5.5 |
2060-1270 |
Description mechanical marks
| Name |
Description |
| σU |
Limit short-term strength |
Technological properties
| Name |
The value |
| Macrostructure and pollution |
The macrostructure of the wire rod according to TU 14-1-4104-86 should not have traces of shrinkage, axial looseness, cracks, inclusions and placenow, bundles. Pollution steel non-metallic inclusions on the average score must not exceed the sulphides and the silicates 1 point each, oxides 1.5 points. The maximum score of non-metallic inclusions of all types should not exceed 2 points. |
| Microstructure |
The microstructure of wire rod, on the other 14-1-4104-86 should consist of perlite 1-3 points on a scale of 1 to GOST 8233. In the surface layer of the wire rod is not allowed the presence of the structure of sorbitol vacation. Martensitic and toostonedtocare areas are not allowed. The average depth bezoperatsionnogo layer (ferrite + transition zone) of the rod surface must not exceed 2% at maximum depth of not more than 2.5% of the diameter. |
