NX344 / 1.2344 ESR Forged Blocks for Plastic Mold
NX344 is a special grade which is developed by our Ningshing Special-Steel.
It is high quality level of 1.2344 ESR, a kind of hot work tool steel.
At the beginning, we develop this grade for making plastic mold for high-grade of snack box because of its better performance on thermal resistance and good toughness that could improve to get a longer lifetime of the mould.
| C | Si | Mn | P | S | Cr | Mo | V |
| 0.36 | 0.90 | 0.30 | ≤ | ≤ | 5.00 | 1.25 | 0.90 |
| 0.42 | 1.20 | 0.50 | 0.015 | 0.003 | 5.50 | 1.50 | 1.20 |
| Thickness(mm) | Width(mm) | Length(mm) | ||||||
| 100-500 | 100-910 | 3000-5800 | ||||||
EAF+LF+VD+(ESR), Forged, Spheroidizing Annealed, EFS, Hardness≤230HB, Machined surface,
UT 100% SEP1921 Class 3 E/e,
Spheroidized Microstructure as per standard NADCA207-2003 AS1-AS9
Impact test: Transverse impact test as per ASTM A370, V notch impact test (5 samples, size of 10 x 10 mm),
average value >=11 J (delete max. and min.), single value >=8 J
Heat Treatment
| Heat Temperatule | Start Forging Temperature | Finish Forging Temperature | Cooling Method | ||||||||
| 1020-1150℃ | 1100-1120℃ | 900-850℃ | Pit or Sand Cooling |
Annealing
750 to 800°C (1382 to 1472°F)
Slow controlled cooling in furnace at a rate of 10 to 20°C/hr (50 to 68°F/hr) down to approx. 600°C (1112°F), further cooling in air.
Hardness after annealing: max. 235 HB.
Stress relieving
600 to 650°C (1112 to 1202°F)
Slow cooling in furnace; intended to relieve stresses set up by extensive machining, or in complex shapes.
After through heating, hold in neutral atmosphere for 1 - 2 hours.
Hardening
1000 to 1040°C (1832 to 1904°F)
Oil, salt bath (500 - 550°C / 932-1022°F), air
Holding time after temperature equalization: 15 to 30 minutes.
Obtainable hardness:
52 - 56 HRC in oil or salt bath,
50 - 54 HRC in air.
Tempering
Slow heating to tempering temperature immediately after hardening / time in furnace 1 hour for each 20 mm of work piece thickness, but at least 2 hours / cooling in air. It is recommended to temper at least twice. A third tempering cycle for the purpose of stress relieving may be advantageous.
1st tempering approx. 30°C (86°F) above maximum secondary hardness.
2nd tempering to desired working hardness.
The tempering chart shows average tempered hardness values.
3rd for stress relieving at a temperature 30 - 50°C (86 to 122°F) be low highest tempering temperature.
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