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718H pre-hardened plastic mold steel FT62
As a pre-hardened die steel, the 718 H has the following excellent properties: no heat treatment risk, no heat treatment cost, shorter production time (no heat treatment), lower die making cost (no correction of deformation), easy die modification processing, can be followed by nitridation or local flame quenching, improve surface strength and wear resistance, and reduce surface failure.Chemical composition %
| C | Si | Mn | Cr | Ni | Mo | P | S | FactoryStatus |
| 0.32/0.40 | 0.20/0.40 | 1.10/1.50 | 1.70/2.0 | 0.85/1.15 | 0.25/0.40 | ≤0.030 | ≤0.030 |
Prehard 30~38HRC |
Tempering curve
The tempering curve sample size is 15x15x40 mm austenitizing temperature is 850℃, holding 30 minutes, and then air cooling. Then temper it for 2+2 hours.
Nitriding and nitriding
Nitriding can increase surface hardness, increase resistance to wear and erosion, nitriding surface can also improve the ability to resist erosion
Process: finishing →550℃ stress-removing tempering → grinding machine processing → nitriding treatment
Electrosparking
If the mold is in the supply state to do EDM, after the processing needs to be about 550℃ of tempering treatment, if the steel has been re-hardened treatment, EDM should choose 25℃ lower than the last tempering temperature for tempering.
Welding
Proper preheating and groove preparation before welding, selecting the correct welding material and welding process can obtain satisfactory welding effect.
Polished
Supply 718H has excellent polishing performance. After grinding, aluminum oxide or drilling gypsum for polishing
Typical Process
1. Reserve a margin of 0.05mm after grinding.
2.Using 45 # drill gypsum polishing to achieve uniform surface.
3. Use 15# diamond paste to polish.
4. Use 3# diamond paste to polish, the mold with high surface is polished with 1# diamond paste.
Hard chrome plating
after hard chrome plating, the mold must be tempered at 180℃ in time for 4 hours to avoid hydrogen embrittlement.
Flame or induction quenching
718H can be quenched to hardness about 50 by induction or flame HRC, according to the mold design, flame quenching may lead to different degrees of deformation, flame hardening is best done after roughing the mold surface, and then surface finishing.
