| Grade : | 70 ( 70 ) |
| Substitute: | 65Г |
| Classification : | Spring structural steel |
| Equivalent grades: | Go here |
Chemical composition in % for grade 70 ( 70 )
| C | Si | Mn | Ni | S | P | Cr | Cu |
| 0.67 - 0.75 | 0.17 - 0.37 | 0.5 - 0.8 | max 0.25 | max 0.035 | max 0.035 | max 0.25 | max 0.2 |
Temperature of critical points for grade 70 ( 70 ).
| Ac1 = 730 , Ac3(Acm) = 743 , Ar3(Arcm) = 727 , Ar1 = 693 |
Mechanical properties under Т=20oС for grade 70 ( 70 )
| Assortment | Dimension | Direct. | sв | sT | d5 | y | KCU | Heat treatment |
| - | mm | - | MPa | MPa | % | % | kJ / m2 | - |
| Bar, GOST 14959-79 | to Ø 80 | 1030 | 834 | 9 | 30 | Guenching 830oC, oil, Drawing 470oC, | ||
| Band cold-worked , GOST 2284-79 | 740-1130 | |||||||
| Band annealed , GOST 2284-79 | 440-740 | 10 |
| Brinell hardness for 70 ( 70 ) (without heat treatment) , GOST 14959 | HB 10 -1 = 269 MPa |
| Brinell hardness for 70 ( 70 ) (annealing) , Sheet trick GOST 1577-93 | HB 10 -1 = 229 MPa |
Technological properties for grade 70 ( 70 )
| Weldability: | is not used. |
| Flakes : | weakly predisposed |
| Temper brittleness: | not predisposed |
Physical properties for grade 70 ( 70 )
| T | E 10- 5 | a 10 6 | l | r | C | R 10 9 |
| Grade | MPa | 1/Grade | Watt/(m·Grade) | kg/m3 | J/(kg·Grade) | Ohm·m |
| 20 | 2.06 | 7810 | ||||
| 100 | 11.5 | 68 | 483 | |||
| 200 | 12.3 | 52 | 487 | |||
| 300 | 13 | 37 | ||||
| 400 | 13.8 | 29 | 521 | |||
| T | E 10- 5 | a 10 6 | l | r | C | R 10 9 |
Equivalent steels for grade 70 ( 70 )
| USA | Germany | Japan | France | England | European | Italy | China | Sweden | Bulgaria | Poland | Romania | Czechia | Australia | ||||||||||||||||||||||||||||||||||
| - | DIN,WNr | JIS | AFNOR | BS | EN | UNI | GB | SS | BDS | PN | STAS | CSN | AS | ||||||||||||||||||||||||||||||||||
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Types of delivery of grade 70 ( 70 )
| В22 - Graded and shaped rolling |
| B23 - Sheets and Strips |
| В32 - Graded and shaped rolling |
| B33 - Sheets and Strips |
| B34 - Ribbons |
| В71 - Low-carbon steel wire |
| В72 - Medium-high and high-carbon steel wire |
Specification :
| Mechanical properties : | |
| sв | - Tensile strength , [MPa] |
| sT | - Yield stress, [MPa] |
| d5 | - Specific elongation at fracture , [ % ] |
| y | - Reduction of area , [ % ] |
| KCU | - Impact strength , [ kJ / m2] |
| HB | - Brinell hardness , [MPa] |
Physical properties : | |
| T | - Test temperature , [Grade] |
| E | - Young modulus , [MPa] |
| a | - Coefficient of linear expansion (range 20o - T ) , [1/Grade] |
| l | - Termal (heat) condition coefficient , [Watt/(m·Grade)] |
| r | - Density , [kg/m3] |
| C | - Specific heat ( range 20o - T ), [J/(kg·Grade)] |
| R | - Electrical resistance , [Ohm·m] |
Weldability : | |
| without limitations | - welding is done without heating and subsequent heat treeting |
| limited weldability | - welding is possible under heating up to 100-120 grade and subsequent heat treeting |
| hard weldability | - obtaining the quality welding needs the additional operations:heating up to 200-300 grade; the heat treeting ia annealing |
70 ( 70 ) - Spring structural steel: chemical composition, mechanical and physical properties, hardness
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