1.2083 Tool Steel: Composition, Properties And Performance

When a supplier quote comes back listing “1.2083” and your project spec calls for corrosion resistant mold steel, the clock starts ticking. You need to know quickly whether this grade’s chromium content delivers the polishability and rust resistance your transparent housing or medical connector mold demands, or whether you’re looking at a mismatch dressed up in familiar numbers. Confusion deepens when someone on the sourcing side swaps in “420 stainless” or “S136” as if they are interchangeable. That assumption has ended more than a few mold programs in unplanned rework.

This breakdown gives you the standard composition range, the hardness HRC mold steel data across tempering stages, and a side-by-side comparison against 420, S136, and 8407 tool steel so you can quote with verified numbers.

2083 Steel Composition: Standard Chemical Composition Table

1.2083 covers a range rather than one rigid recipe. It is the DIN W.-Nr. designation for X42Cr13, sold as AISI 420 or 420SS plastic-mould tool steel, and the exact melt chemistry shifts across mills.

Engineers work from this baseline range:

Nickel, molybdenum, and vanadium count as residuals, so standard 1.2083 mill test certificates rarely track them.

Why the Numbers Vary by Supplier

Common suppliers formulate the steel with small variations:

• ASSAB 2083: C 0.38, Cr 13.00

• 1.2083 ESR typical: C 0.40, Cr 13.00, S as low as 0.003%

• X42Cr13 spec: C 0.36–0.42, Cr 12.50–14.50

• General datasheet range: C 0.38–0.45, Cr 12.00–13.50

Electroslag remelted (ESR) material drives sulfur far below the standard ≤0.030% limit down to ≤0.003%. That low sulfur content prevents pitting and lets you achieve a true mirror polish in the mold cavity.

What to Specify on Your PO

Lock these down before the material ships:

• Grade: DIN EN 1.2083 / X42Cr13

• Chromium: 12.50–13.50% (procurement-grade preference)

• Sulfur: ≤0.005% preferred, ≤0.003% for ESR

• Manufacturing route: ESR/ESU when polishability and low inclusion content matter

Trust the actual chemical analysis on the mill cert instead of the brand name on the catalog page.

Chromium Content in 1.2083 and Corrosion Resistance

Thirteen percent chromium separates 1.2083 tool steel from standard tool steel. That percentage forms the passive chromium-oxide surface film required for corrosion-resistant mold cavities. Still, chemistry alone tells only part of the story, because the martensitic structure requires specific heat treatment before that protection develops.

To develop full corrosion resistance, follow this sequence:

• Quench and harden the block

• Temper at low temperature

• Fine-polish the working surface

Skip any step and the passive layer never forms properly. Hardness reaches 50–54 HRC under this cycle, matching what you would expect from AISI 420 mold steel under similar treatment.

Not all of that 13% chromium remains free for passivation, because hardening locks part of it into carbides. As a result, nominal composition overstates actual corrosion performance.

Compared to D2 (1.2379) tool steel, 1.2083 polishes better and resists corrosion more effectively, while D2 provides higher wear resistance from its carbide volume. Against 420 stainless steel equivalents, melt cleanliness varies enough that ESR/ESU sourcing matters more than the spec sheet number.

Check every mill cert for actual Cr%, carbon and sulfur levels, and heat-treatment hardness instead of assuming 13% guarantees stainless-grade protection. Performance does not match 304 or 316, so evaluate 1.2083 tool steel strictly as corrosion-resistant tool steel.

2083 Steel Properties and Performance Data

Actual test numbers tell the story. Below is the mechanical and physical performance data you need before specifying this grade on a drawing.

Mechanical Properties by Condition

These 40–52 HRC figures shift with section thickness, quench medium, tempering cycle, and test direction. Confirm final numbers against your supplier’s test block results.

Physical Properties Across Temperature

Heat Treatment Parameters That Produce These Numbers

• Austenitizing: 1,000–1,050°C

• Holding time: 15–30 minutes post-temperature, scaled to section size

• Quenching: oil, compressed gas, or hot bath; controlled cooling cuts distortion and cracking risk

• Tempering: double tempering is standard practice

• Final hardness window: 53–56 HRC with proper process control

• Stress relieving: apply after rough machining and before final hardening when dimensional stability matters

Prehardened stock skips this cycle, saving you a processing step if your tolerance window permits.

2083 Heat Treatment Parameters and Hardness Curve

A full heat treatment cycle for 1.2083 tool steel runs through five stages, and cutting corners on any of them throws off your final hardness. Shops that rush the furnace schedule end up with cracked cavities or soft spots that fail mid-production.

The Complete Process Sequence

• Soft annealing: 760–800°C, hold ~2 min/mm, furnace-cool to below 240 HB / 23 HRC

• Stress relief: ~650°C with slow furnace cooling, run after heavy machining

• Preheating: two-stage ramp at ~400°C then ~650°C (some shops specify 600–850°C)

• Austenitizing: 1000–1050°C, with standard production held at 1020–1030°C

• Quenching: oil, vacuum gas, or a 500–550°C hot bath; pick the mildest medium that still hardens through

Tempering Temperature vs. Hardness Curve

The small bump at 500°C reflects secondary hardening. It drops off quickly once you push past 600°C, where hardness collapses to 39 HRC.

Three Practical Schedules

• Maximum wear resistance: double temper at 150–200°C → 58–62 HRC

• Balanced mold-tool condition: double temper at 250°C, 2h per cycle → 55–58 HRC, better corrosion resistance

• Higher toughness: double temper at 400–500°C → 50–54 HRC

Cool the steel down to ~30°C between cycles every time. Skipping that step ruins the whole sequence.

2083 vs 420, S136, and 8407 Steel

Four grades keep showing up on the same bid sheet, and three share enough traits to mask real differences in performance. 8407 tool steel stands apart from the group: a hot-work steel categorized alongside mold steels for convenience rather than chemistry.

Chemistry and Hardness Side-by-Side

8407 holds about a third of the chromium found in 2083. That chemistry makes it a fit for die casting and hot forming, while high-corrosion cavity work demands the higher chromium of the other three.

Where Each Grade Actually Wins

• 2083 — A cost-effective baseline for general plastic injection tooling that requires moderate corrosion resistance and a clean polish.

• 420 — Works when a broad AISI spec satisfies the drawing, though the grade covers a wide carbon spread. Verify the specific subtype before purchasing, because unrefined 420 bar offers looser tolerances than dedicated mold blocks.

• S136 — The top option for mirror polishing. ESR processing removes inclusions, and Stavax ESR matches conventional 1.2083 in the soft state with ~13.6% Cr and an annealed hardness near 190 HB.

• 8407 — The right call when thermal cycling, shock, or gross cracking risk outweighs rust concerns. It provides high impact toughness and thermal-fatigue resistance with minimal corrosion protection.

Substitution Reality Check

You can swap 2083 and S136 tool steel directly once mill certs verify the ESR melt route and low sulfur content. Interchanging 2083 and 420 requires matching your target hardness against specific carbon limits, since commercial 420 stock often lacks mold-grade steel cleanliness. Switching from 2083 or S136 to 8407 tool steel trades corrosion protection for hot-service toughness, making it an intentional design change rather than a direct material swap.

2083 Applications in Plastic Injection Molds

Most 1.2083 purchase orders come from three industries: medical, optical, and food packaging. All three depend on the same two properties: corrosion resistance and mirror polish.

Where 2083 Earns Its Keep

Match your project against these use cases before committing:

• PVC and aggressive plastics: Pipe fittings, window profiles, and flooring tiles. These resins release corrosive gases during molding, as do POM and flame-retardant compounds.

• Transparent and high-gloss parts: Polycarbonate lenses, acrylic covers, and light guides. ESR stock delivers a surface finish down to Ra ≤ 0.05 μm.

• Medical components: Syringe bodies, connectors, and pharmaceutical containers. Strict hygiene standards rule out lower-chromium steels.

• Optical products: Camera lenses, solar lenses, and diffusers. Polish quality directly determines part rejection rates here.

• Abrasive-filled plastics: Glass-fiber or mineral-reinforced resins, which wear down standard P20 cavities faster than 2083.

Component-Level Fit

2083 shows up most often as:

• Mold inserts and cavities

• Core pins and ejector sleeves

• Small- to medium-sized tooling blocks

Standard P20 lacks the chromium needed for PVC and POM service, and it cannot take the same polish. Choose 2083 when corrosion resistance or optical clarity outweighs initial material savings.

2083 Machining, Polishing, and EDM Recommendations

Cutting sequence determines whether your cavity reaches spec or your tooling budget blows up. Get the order wrong on 1.2083 and you’ll burn through carbide inserts before lunch.

Machining Sequence That Saves Tool Life

Rough everything in the annealed condition, where hardness sits ≤230 HB. Carbide tooling handles this stage fine, but pushing those same tools into hardened stock wear them out immediately.

Once hardened and tempered, switch to CBN grinding for final sizing. Conventional milling on hardened surfaces chews up inserts and risks thermal damage to the cavity. For the workflow, rough the annealed block, harden and temper to your target (48–52 HRC for most mold work, though some specs allow 50–54 HRC), then finish by hard milling or EDM. Leave 0.1–0.3 mm of stock for final finishing operations.

Polishing to SPI A1

ESR-quality 2083 reaches an SPI A1 mirror finish when steel cleanliness and prep work are controlled. Low inclusion content is what prevents pitting during the polish.

Strip the EDM recast layer, grinding marks, and machining scratches before diamond polishing starts. Work abrasives in sequence: #240 → #400 → #600 → #800 → #1200 → #2000, then move to diamond compounds. Supplier data shows achievable roughness down to Ra ≤0.05 μm. Stop each grit stage as soon as the previous scratches vanish, since over-polishing rounds edges and distorts cavity geometry.

EDM: Use It, Then Fix It

EDM suits hardened 2083 tool steel for deep ribs, sharp corners, and tight-tolerance features where cutting tools struggle. The catch is that hardened 2083 forms a brittle recast white layer during EDM that cracks under fatigue if left in place.

Rough with standard removal rates, then finish with low-current, high-frequency fine sparking to limit surface damage. Grind or stone away the remaining 5–10 μm white layer afterward. Once EDM is done on hardened and tempered stock, stress-relieve at 20°C below your last tempering temperature. Treat EDM as a pre-finishing step, never the final surface.

2083 Mold Steel Selection Decisions by Project Condition

Whether 1.2083 belongs on your BOM or gets replaced by a cheaper grade comes down to ten project scenarios. Check your requirements against this table before finalizing the steel.

Skip 2083 if toughness, simple weld repairs, or lower machining costs matter more to the build than corrosion resistance and polishability.

2083 Technical Parameters to Include in a Supplier RFQ

A vague RFQ invites a vague quote, and vague quotes on tool steel turn into schedule disasters three weeks before T1. Nail down these fields before you send anything to a supplier.

Material and Certification Line Items

Specify the exact grade (DIN 1.2083 / X42Cr13) tool steel, melt route (ESR vs. conventional), chromium range, sulfur cap, target hardness in HRC, and the required mill test certificate. State whether the DIN 1.2083 standard or an internal spec governs, and note which takes precedence if the drawing and spec conflict.

Process and Inspection Fields

Require the heat-treatment procedure, tempering curve data, hardness test method, sampling location, and acceptance limits. Include first-article inspection, surface finish grade (SPI reference), and pre-shipment hardness verification before you accept delivery.

Conclusion

Selecting pre-hardened mold steel comes down to matching chemistry and hardness to the part sitting in your tooling. With chromium content around 13%, a working hardness of 30-35 HRC, and corrosion resistance that outperforms generic tool steels, 1.2083 tool steel delivers 420 stainless steel equivalent performance without the premium price tag of S136 in molds requiring moisture resistance, transparency, or a mirror finish.

If your project involves medical-grade components, optical lenses, or any mold requiring consistent polishability over tens of thousands of cycles, you now have the composition tables, heat treatment curves, and comparison data to make that call with confidence.

Before you send out an RFQ, pull the technical parameters outlined above and attach them to your supplier inquiry. A five-minute spec check now saves weeks of mold rework later.