Home > Special steel > Plastic Mold Steel > 420FM 1.2085 SUS420F plastic mold steel

420FM 1.2085 SUS420F plastic mold steel

1.2085 tool steel delivers outstanding corrosion resistance, superior machinability and consistent dimensional stability. It is ideal for corrosion-resistant plastic molds, food-grade & medical component molds and high-volume precision wear parts.

Standard: AISI 420FM, DIN 1.2085(X33CrS16), JIS SUS420F, GB 3Cr16NiMoVS
Technique: EAF + LF + VD, forged, multi-directional forging ratio ≥4, quenched and tempered (pre-hardened), controlled sulfur addition for excellent machinability
Shape: Round, Flat, Plates, Blocks
Heat treatment: Supplied in pre-hardened condition, typical hardness 28–32 HRC (quenched and tempered); higher hardness available on request
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 1.2085 in various custom sizes

Chemical Composition (%)

Grade	C	Si	Mn	P (≤)	S	Cr	Mo	V	Ni
1.2085 (X33CrS16)	0.28–0.38	≤1.00	≤1.00	0.030	0.05–0.10	15.00–17.00	—	—	≤1.00
420FM (420F mod)	0.26–0.40	≤1.00	≤1.25	0.040	0.08–0.15	12.00–14.00	0.20–0.50	—	≤0.60
SUS420F	0.26–0.40	≤1.00	≤1.25	0.060	≥0.15	12.00–14.00	—	—	—
3Cr16NiMoVS	0.28–0.38	0.30–0.70	0.50–1.00	0.030	0.05–0.10	15.00–17.00	0.40–0.80	0.10–0.30	0.50–1.00

Main characteristics of 1.2085 tool steel

Excellent corrosion resistance - withstands corrosive plastic materials
Superior machinability - reduces machining time and tool cost
Good polishability - delivers high-quality mold surface finish
High dimensional stability - maintains tight working tolerances

420FM | 1.2085 | SUS420F tool steel applications

1.2085 steel for Corrosion-Resistant Plastic Mold

1.2085’s 16% chromium and controlled sulfur provide excellent resistance to acidic gases and easy chip evacuation, making it the standard choice for PVC and chemically aggressive plastic molding.

1.2085 steel for Food-Grade & Medical Component Mold

Good polishability combined with reliable corrosion resistance ensures hygienic, easy-to-clean surfaces for molds used in food packaging and medical device components.

1.2085 steel for High-Volume Precision Wear Parts

The pre-hardened condition and superior machinability of 1.2085 enable efficient, high-speed production of corrosion-resistant precision components without additional heat treatment.

Our Production Technology For 1.2085 (X33CrS16 / 420FM / X35CrS16) Prehardened Corrosion-Resistant Plastic Mold Steel

Ultrasonic testing (UT) 100% as per EN 10228-3 Class 4 or SEP 1921 Class E/e (upon request)
Micro Cleanliness as per ASTM E45 or DIN 50602
Delivery condition: Quenched and tempered (prehardened), hardness 280 – 325 HB (29 – 35 HRC)
Alternative delivery: Soft annealed, hardness max. 230 – 250 HB for specialized machining

mechanical properties & heat treatment of 1.2085 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 760 – 800°C (760–780°C typical per some sources, 720–750°C per others)
Hold at temperature for sufficient time (minimum 2 minutes per mm of section thickness, or 2–5 hours depending on section thickness)
Cool slowly in the furnace to room temperature
Hardness after annealing: max. 230 – 250 HB
Annealing in a protective atmosphere is recommended to reduce decarburization and surface scaling

Hardening

1.2085 is typically used in the prehardened delivery condition and does not require additional heat treatment. Rehardening is only required when the steel has been annealed after forging and requires restoration to prehardened condition, or when specific application requirements demand a different hardness level.
Pre-heating (recommended): Preheat in two stages — first stage at 450 – 500°C, second stage at 800 – 850°C — to reduce thermal shock and minimize distortion
Austenitizing temperature: 1000 – 1050°C.
Meusburger range: 1000 – 1030°C.
JKZ range: 1000 – 1050°C.
Birlesik Metal range: 1000 – 1050°C.
OTAI range: 1000 – 1030°C.
Recommended standard range: 1000 – 1050°C for optimal hardness
Holding time: After temperature equalization, hold for at least 1 minute per mm of section thickness (minimum 30 minutes for larger sections)
Quenching media:
Oil (preferred for most sections) — provides maximum hardness with good distortion control
Polymer — also suitable, providing better distortion control for complex shapes
Hot bath — as an alternative for complex shapes requiring minimum distortion
Air — for smaller sections only, but may result in lower hardness
Hardness after quenching: approx. 51 – 55 HRC, typically 48 – 55 HRC.

Stress relieving

Perform after rough machining or heavy stock removal, especially for tools with complex shapes or unbalanced cross-sections, to reduce the risk of distortion during further processing
For quenched and tempered (prehardened) material: heat carefully to 500 – 550°C (maximum 550°C). When stress-relieving the material after processing, keep the material at temperature in a neutral atmosphere for at least 2 hours after complete heating, then slowly cool the oven at 20°C/hour to 200°C, then cool in air
For soft annealed material or general stress relief: heat carefully to 590 – 650°C (600–650°C per JKZ)
Hold at temperature for 1 – 2 hours (minimum holding time 2 minutes per mm of section thickness)
Air cool or furnace cool after holding
This operation is recommended to eliminate residual stresses induced by mechanical working and reduce distortion during further processing. To be carried out after machining to eliminate residual stresses induced by mechanical working

Tempering

Temper immediately after the workpiece cools to hand-warm temperature (approx. 50–70°C). Delayed tempering may cause cracking
Number of tempers: Minimum 2 times. Double tempering is recommended to improve toughness and ensure complete transformation of retained austenite.
Second temper must be performed at a temperature max. 30°C below the first tempering temperature
Holding time: Soak for at least 3 minutes per mm of section thickness (minimum 2 hours per cycle). Minimum time in furnace: 2 hours per 20mm part thickness
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. 48–55 HRC) with good wear resistance.
200 – 500°C (medium-temperature tempering) : For balanced hardness and toughness (approx. 46–48 HRC) — hardness remains relatively stable across this range.
550 – 610°C (high-temperature tempering) : For prehardened delivery condition (approx. 28–35 HRC / 280–325 HB)

Why Choose NSPM as Your 1.2085 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.