1730 is an unalloyed steel used for general moulding applications and frames or accessories
1730
- is produced by a process that ensures a good level of cleanliness and homogeneity.
- is a non alloyed steel with a carbon percentage near 0.45%
- can be surface hardened by induction or laser with a hardness up to 57 HRC. The hardened layer will be 2 mm deep in case of induction hardening and 1mm in case of laser hardening.
- is delivered at a hardness of 200 HB and can be machined without further heat treatment.
Applications
1730 can be used for moulding cavities without severe polishing or texturing requirements.
1730 can be used for all the secondary parts in molding applications and also frames for plastic moulds.
1730 can also be used for mechanical applications requiring a hardness around 200 HB, as hydraulic parts.
Main properties
- Unalloyed steel at 200 HB ready to be machined without any further heat treatment
- Suitable for easy moulding cavities.
- Excellent thermal conductivity, better than alloyed steels
- Good machinability
- Suitable for surface treatments
Chemical composition (typical)
| C | Mn | Si | P | S | Cr, Ni | Mo | Cr+Ni+Mo |
|---|---|---|---|---|---|---|---|
| 0.42 | 0.60 | 0.15 | Max | 0.020 | maxi | maxi | Max |
| 0.50 | 0.80 | 0.40 | 0.025 | 0.035 | 0.40 | 0.10 | 0.63 |
Designation
| EN – ISO | Werkstoff | USA | UK | Japan JIS | Other |
|---|---|---|---|---|---|
| C45E C45R C45U |
1.1191 1.1201 1.1730 |
1045 | 080 M46 | S45 | XC48 (NF), Ck45 (DIN) |
Hardness at the time of delivery
Annealed for 250 HB max.
Typical mechanical properties on normalized steel measured at ¼ thickness (max 80mm) (results from internal tests not indicated on the certificates)
| Thickness mm |
Tensile strength MPa |
Yield strength 0.2% MPa |
KV impact test +20°C J |
|---|---|---|---|
| ≤100 | Min 580 | Min 305 | NA |
| 100<tr≤250 | Min 560 | Min 275 | Min 18Long/10transverse |
| ≥250tr | Min 540 | Min 240 | Min 15Long/10tranverse |
Physical properties
| Temperature | 20°C | 100°C | 200°C | 300°C |
|---|---|---|---|---|
| Volumic mass kg/m³ | 7850 | 7810 | 7780 | 7760 |
| Young Modulus N/mm² | 205 000 | 202 000 | 195 000 | 190 000 |
| Thermal conductivity W/m.K | 45 | 42 | 39 | 37 |
| Coefficient of linear expansion 10-6/K | 11.5 | 11.8 | 13 | 13.2 |
Heat treatment
The 1730 is delivered for max 250HB and there is no need for further heat treatment. In the case of mechanical applications it is recommended to use normalized 1730.
In case of need (e.g. if other mechanical properties are required) the following parameters can be used.
Soft annealing
Temperature: 680 – 710°C, duration 1h + 1h for 25mm thickness. slow cooling in the oven (10 to 20°C/h). The atmosphere in the furnace must be reducing to avoid decarburization of the steel.
Stress relieving
after machining, it is recommended to perform stress relieving at 550°C maximum for a minimum of 2 hours, followed by slow cooling in the oven to 450°C.
Normalization
In order to avoid any risk of cracking it is recommended to preheat in 2 steps.
- 1st preheating step: temperature: 450°C time: 30 s/mm of thickness
- 2nd preheating step: temperature: 650°C time: 30 s/mm of thickness
Recommended normalizing temperature: 840 – 860° C. The holding time should not be too long to avoid a risk of grain coarsening and a loss of toughness. It is recommended to keep the part at the austenitizing temperature 20 minutes per inch of thickness as soon as the temperature of the surface reach the normalization temperature.
Then cool the block in air at room temperature out side of the furnace for parts with a small thickness (less than 200mm) and in water mist for bigger parts.
Austenitization
In order to avoid any risk of cracking it is recommended to preheat in 1 step.
- 1st preheating step: temperature: 450°C time: 30 s/mm of thickness
- 2nd preheating step: temperature: 650°C time: 30 s/mm of thickness
Recommended austenitizing temperature: 800 – 830°C. The holding time should not be too long to avoid a risk of grain coarsening and a loss of toughness. It is recommended to keep the part at the austenitizing temperature 30 minutes per inch of thickness as soon as the temperature of the surface reach the austenitization temperature.
Quenching medium
Oil at 80°C, vacuum (pressure > 6 bars), salt bath 500 – 550°C.
To ensure good toughness, treatment with oil or salt bath is preferable.
Tempering
To ensure a minimum residual austenite rate as well as greater tool stability, it is essential to perform a double tempering. Each tempering is followed by a cooling under 100°C.
Each tempering time must be at least equal to 1h + 1h for 25 mm of thickness of the treated part (equivalent thermal thickness).
Surface treatment
PVD, CVD
1730 is suitable for all kinds of PVD and CVD treatment as soon as the treatment temperature is 30°C lower than the last tempering temperature.
Polishing
1730 is perfectly suitable for polishing in the treated state and can be used for applications requiring a sufficient level of polish for parts with a good aspect (Rt ≤ 100μm, CNOMO level 3, Rugotest N10).
Optimal polishing is achieved by performing consecutive steps with similar roughness and stopping each step as soon as the last scratch from the previous step disappears.
Induction or laser hardening
1730 can be surface hardened up to 57 HRC by induction or laser. Please consult us for more details. A stress relieving at 150°C for minimum 2h is mandatory after surface hardening.
Machining
The machining parameters below are given for information only and must be adapted according to the equipment and usual machining conditions.
Turning
| Carbide tool | ||
|---|---|---|
| Rough machining | Finishing | |
| Cutting speed m/min | 200 – 250 | 250 – 300 |
| Feed mm/r | 0.25 – 0.55 | 0.2 – 0.3 |
| Depth of cut mm | 2 – 5 | 1.5 – 2.5 |
Milling: surfacing
| Milling with carbide tools Rough machining |
Solid tool Finishing |
|
|---|---|---|
| Cutting speed m/min | 200 -150 | 250 – 300 |
| Feed mm/r | 0.15 – 0.35 | 0.1 – 0.2 |
| Depth of cut mm | 2 – 5 | 2 |
Drilling: HSS twist drill
| Drill diameter mm | Cutting speed m/min | Feed mm/t |
|---|---|---|
| < 5 | 20 – 22 | 0.05 -0.15 |
| 5 – 10 | 20 – 22 | 0.15 – 0.25 |
| 10 – 15 | 20 – 22 | 0.25 – 0.35 |
| 15 – 20 | 20 – 22 | 0.35 – 0.42 |
Drilling: carbide drill
| Carbide type | |||
|---|---|---|---|
| Indexable insert | Solid carbide | Carbide tip | |
| Cutting speed m/min | 150 – 170 | 90 – 120 | 50 – 70 |
| Feed mm/t | 0.05 – 0.10 | 0.10 – 0.25 | 0.15 – 0.25 |
Electro-discharge machining
1730 is also suitable for EDM machining (wire or electrode). Preferably, the machining will be carried out with a low current density and a high frequency in order to limit the thickness of the white layer as much as possible.
Then it is necessary to carry out a stress relieving at 25°C below the last tempering in order to reduce the level of residual stresses (which could lead to a risk of cracking) and to carry out a polishing to completely remove the white layer formed during the discharge machining process.
Welding
1730 could be welded in the heat treated condition.
- Method: TIG
- Feeder wire: 25CrMo4
- Preheating: 300°C. Hold at 200°C during the welding operation with a maximum interpass temperature at 350°C. Slow cooling (max 20°C/h) after welding.
- Post treatment: At 550°C, duration 1h + 1h for 25mm of thickness. slow cooling in the oven (10 to 20°C/h). Hardness of the welded area: ≈250HB.
Please consult us for more details.
Download the 1730 datasheet (PDF)
More grades: Plastic Mold Steels. Where to buy: Service Network.
