24 July 2021 Structural Steel Bar
DIN 1.7243 Structure Steel Bar
DIN 1.7243 (equivalent to 18CrMo4 )standard applies to manufacture of bearing ring steel pipe rolling elements made by high-carbon chromium bearing steel processed with hot rolled forged round, steel wire, cold rolled. Continuous casting steel is not recommended to be the material of balls.
DIN 1.7243 steel is one of popular alloy steel used for engineering purpose, like fasteners, high pressure pipe and more advanced carburized parts, such as gear, shaft, etc. which work in the noncorrosive medium and temperature below 250 ℃, working with nitrogen hydrogen mixture in the medium.
Chemical Composition:
| C | Si | Mn | P | S | Cr | Mo |
|---|---|---|---|---|---|---|
| 0.15 - 0.21 | max 0.4 | 0.6 - 0.9 | max 0.025 | max 0.035 | 0.9 - 1.2 | 0.15 - 0.25 |
Mechanical properties - DIN 1.7243:
| Mechanical and physical properties | ||
|---|---|---|
| Tensile strength | Rm | > 1080 MPa |
| Yield point | Re | > 880 MPa |
| Contraction | Z | > 50% |
| Elongation | A | > 10% |
| Notch toughness | KU2 | > 72 J |
| Hardness in softened state | HB | < 217 HB |
| Density | ρ | 7,85 kg/dm3 |
Mechanical properties for individual dimensions:
| Mechanical properties after hardening | ||||
|---|---|---|---|---|
| Properties | Dimensions | |||
| 11mm | 30mm | 63mm | ||
| Tensile strength | Rm | 920 - 1270 MPa | 820 - 1170 MPa | 710 - 1060 MPa |
| Yield point | Re | > 600 MPa | > 540 MPa | > 480 MPa |
| Notch toughness | KU | > 25 J | > 25 J | > 25 J |
| Elongation | A | > 9 % | > 10 % | > 11 % |
Heat treatment of DIN 1.7243 steel:
| Process | Cooling | Temperatures |
|---|---|---|
| Normalizing annealing | in air | 870 - 900℃ |
Softening annealing | 650 - 700℃ | |
| Carburizing in powder |
| 880 - 950℃ |
| Carburization in salt baths | 900 - 950℃ | |
| Gas carburization | 880 - 900℃ | |
| Hardening (I) |
| 860 - 900℃ |
| Hardening (II) |
| 800 - 840℃ |
Tempering | 170 - 200℃ | |