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420 1.2083 SUS420J2 plastic mold steel

1.2083 tool steel boasts excellent polishability, strong corrosion resistance, high hardness and dimensional precision. It is widely used for optical molds, corrosion-resistant plastic molds and precision thread rolling dies.

Standard: AISI 420, DIN 1.2083, JIS SUS420J2, GB 40Cr13, ASSAB S136
Technique: EAF + LF + VD or ESR, forged, multi-directional forging ratio ≥4, quenched and tempered (pre-hardened)
Shape: Round, Flat, Plates, Blocks
Heat treatment: Supplied in pre-hardened condition, hardness 28–32 HRC (quenched and tempered). Higher hardness (up to 48–52 HRC) available on request for enhanced wear resistance
Surface Treatment: Turned, milled / ground, sawn ends. Black (hot-rolled / forged surface) available for large sections
Tolerance: flat bars & plates thickness: +0.5/-0.0 mm (turned); forged blocks: ±0.2 mm
MOQ: 1 Ton

We supply DIN 1.2083 in various custom sizes

Chemical Composition (%)

Grade	C	Si	Mn	P (≤)	S (≤)	Cr	Mo	V
420 (AISI)	0.15–0.40	≤1.00	≤1.00	0.040	0.030	12.00–14.00	—	—
1.2083 (X40Cr14)	0.36–0.42	≤1.00	≤1.00	0.030	0.030	12.50–14.50	—	—
SUS420J2	0.26–0.40	≤1.00	≤1.00	0.040	0.030	12.00–14.00	—	—
40Cr13 (4Cr13)	0.36–0.45	≤0.60	≤0.80	0.040	0.030	12.00–14.00	—	—
S136	0.38–0.42	0.30–0.50	0.50–0.80	0.030	0.030	13.50–14.50	0.40–0.60	0.10–0.30

Main characteristics of 1.2083 tool steel

420 | 1.2083 | SUS420J2 tool steel applications

1.2083 steel for Optical Mold

Superb polishability and high cleanliness enable 1.2083 to achieve flawless mirror finishes, meeting the extreme surface requirements of precision lenses and optical components.

1.2083 steel for Corrosion-Resistant Plastic Mold

High chromium content provides excellent resistance to corrosive gases released during processing of PVC, POM, and flame-retardant plastics, significantly extending mold life.

1.2083 steel for Precision Thread Rolling Die

Good wear resistance combined with reliable corrosion protection makes 1.2083 suitable for thread rolling dies operating in damp or mildly corrosive environments, ensuring thread precision.

Our Production Technology For 1.2083 (X40Cr14 / 420 / S136 / 4Cr13) Martensitic Stainless Plastic Mold Steel

Ultrasonic testing (UT) 100% as per EN 10228-3 Class 4, SEP 1921 Class E/e, or ASTM A388 (upon request)
Micro Cleanliness as per ASTM E45 or DIN 50602 (ESR grade offers significantly reduced non-metallic inclusions)
Spheroidized microstructure as per relevant tool steel standards
Delivery condition: Soft annealed, hardness max. 230 – 241 HB (approx. 23 HRC)
Pre-hardened delivery available: 28 – 34 HRC upon request, tempered at 580–620°C

mechanical properties & heat treatment of 1.2083 steel

Heat temperature	Start forging temperature	Finish forging temperature	Cooling method
1050 – 1150 °C	1050 – 1100 °C	≥ 850 °C	Pit, sand, or furnace cooling

Annealing

Heat slowly and uniformly to 750 – 830°C (soft annealing). Widely accepted range: 750–800°C to 830°C
Hold at temperature for sufficient time to ensure uniform heating (approximately 2–5 hours depending on section thickness; minimum holding time 2 minutes per mm of section thickness)
Cool slowly in the furnace at a controlled rate of 10 – 20°C/h down to approximately 650°C
Then air cool to room temperature
Hardness after annealing: max. 230 – 241 HB (approx. 23 HRC)
Annealing in a protective atmosphere is recommended to reduce decarburization and surface scaling

Hardening

1.2083 is a martensitic stainless plastic mold steel that can be hardened in oil, compressed gas, air, or hot bath. The steel exhibits excellent hardenability and obtains its best corrosion resistance when hardened and the surface is ground or polished. Protect the part against decarburization and oxidation during hardening using a protective atmosphere or vacuum. The material is not corrosion-resistant until after hardening — protection against rust must be considered during processing. Temper immediately after quenching.
Pre-heating (recommended): Preheat in two stages — first stage at 400 – 500°C, second stage at 800 – 850°C — and soak thoroughly before austenitizing to reduce thermal shock and minimize distortion.
Alternative preheat range: 600 – 850°C per some sources
Austenitizing temperature: 1000 – 1050°C.
Recommended standard range: 980 – 1020°C (or 1000–1020°C).
Alternative range: 970 – 990°C per some sources; 1020 – 1040°C per others.
For maximum hardness: 1000 – 1020°C is recommended.
For balanced properties: 980 – 1000°C is suitable
Holding time: After temperature equalization, hold for 15 – 30 minutes for smaller sections. General guidelines:
Minimum 1 minute per mm of section thickness at hardening temperature.
For 1020°C: 30 minutes soaking time; for 1050°C: 30 minutes soaking time
Quenching media:
Oil (preferred for most sections) — provides maximum hardness with good distortion control
Compressed gas (high-pressure N₂) — for minimizing distortion, particularly suitable for vacuum furnace applications
Air — for smaller sections and less critical applications, but may result in slightly lower hardness
Hot bath at 500 – 550°C — as an alternative for complex shapes requiring minimum distortion
Hardness after quenching: approx. 53 – 56 HRC.
FUSHUN range: 50 – 54 HRC.
After oil quenching from 1020–1040°C: 48 – 52 HRC.
Oil quenching from 1000–1050°C yields higher hardness (up to 56 HRC)

Stress relieving

Perform after rough machining or heavy stock removal, especially for tools with complex shapes or unbalanced crosssections, to reduce the risk of distortion during final hardening
For quenched and tempered material: heat carefully to 30°C below the tempering temperature used for the prehardened condition
For soft annealed material: heat carefully to 600 – 650°C (approx. 650°C per multiple sources)
Hold at temperature for 1 – 2 hours (minimum holding time 2 minutes per mm of section thickness)
Cool slowly in the furnace, or after holding, cool in air
This operation is recommended to eliminate residual stresses induced by mechanical working and reduce distortion during further processing

Tempering

Temper immediately after the workpiece cools to handwarm temperature (approx. 50–70°C). Delayed tempering may cause cracking
Number of tempers: Minimum 2 times. Double tempering is strongly recommended for all hardening operations to improve toughness, ensure complete transformation of retained austenite, and maximize corrosion resistance.
Second temper must be performed at a temperature 30°C lower than the first tempering temperature
Holding time: Soak for at least 1 hour per 20mm of section thickness (minimum 2 hours per cycle for larger sections, or minimum 1 hour per cycle per some standards).
Minimum holding time: 3 minutes per mm of section thickness per NLMK specifications.
Temper twice after hardening (approx. 2 hours per cycle)
Cooling method: Air cool after each tempering cycle (must cool to room temperature before the next tempering)
Tempering temperature ranges:
150 – 200°C (low-temperature tempering) — For maximum hardness (approx. 52–54 HRC) with excellent wear resistance and good corrosion resistance.
200 – 350°C (medium-temperature tempering) — For balanced hardness and toughness (approx. 48–52 HRC).
380 – 480°C range — Must be avoided due to temper embrittlement risk, which significantly reduces impact toughness and corrosion resistance.
500 – 600°C (high-temperature tempering) — For prehardened delivery condition (28–34 HRC) where maximum toughness and dimensional stability are required.
580 – 620°C — Standard tempering range for pre-hardened condition (28–34 HRC)

Why Choose NSPM as Your 1.2083 Tool Steel Supplier

Source Direct

Direct mill cooperation ensures stable supply, competitive pricing, and consistent quality. Global resource integration and strong supply chain management guarantee reliable material sourcing and long-term availability.

Stock Ready

50,000+ tons inventory across 11 warehouses enables fast delivery. Flexible cutting, short lead times, and ready stock support urgent demands and improve customers’ production efficiency.

Expert Team

600+ professionals, including R&D specialists and technical engineers, provide application-driven support. Fast response and deep tooling knowledge ensure accurate solutions for diverse industrial needs.

Fully Inspected

Strict quality control system with full traceability, UT testing, and heat treatment records. Certified standards (ISO, CE) ensure every material meets high-performance and reliability requirements.

Full-Chain Machining

From steel supply to precision machining, heat treatment, and equipment manufacturing, NSPM offers integrated solutions that enhance accuracy, efficiency, and overall tooling performance.