21MnCr5, steel number 1.2162 under DIN EN 10084:2008, is a manganese-chromium alloy engineered for a precise and demanding purpose: components that must be simultaneously hard at the surface and tough at the core. It is the highest-carbon grade in the Mn-Cr surface hardening family, and after carburizing it routinely achieves 60–62 HRC surface hardness — a benchmark that many competing grades cannot reliably reach.
This guide covers the complete technical picture of 21MnCr5 steel: what it is, how it differs from similar grades, how to heat-treat it, where it is used across industries, how to read its international equivalents, and how to source certified forged parts with full documentation. Written by Jiangsu Liangyi's senior metallurgical team with 25+ years of direct manufacturing experience in this grade.
21MnCr5 and 1.2162: Two Names for One Steel
21MnCr5 is the symbolic material name — derived from composition: approximately 0.21% carbon (C), with manganese (Mn) and chromium (Cr) as primary alloying elements, and "5" representing the scaled Mn content (~1.25% Mn × 4). 1.2162 is the Werkstoffnummer — the unique numeric identifier assigned under the DIN EN system.
Both designations refer to exactly the same material defined in DIN EN 10084:2008, the European standard for case hardening steels. When ordering or specifying forged parts, either designation is valid, but both should appear on the Mill Test Certificate to ensure full material traceability from heat to finished part.
21MnCr5 and 1.2162 are two naming conventions for one identical steel grade under DIN EN 10084:2008. 21MnCr5 is also referenced in ISO 4957 as a tool steel. Always request both designations appear on your EN 10204 3.1 mill test certificate.
Chemical Composition of 21MnCr5 (1.2162)
The chemical composition is defined with tight tolerances in DIN EN 10084. The balance of carbon, manganese, and chromium gives this grade its distinctive combination of hardenability and toughness. Below is the complete specification:
| Element | Symbol | Range (wt %) | Role in Steel Performance |
|---|---|---|---|
| Carbon | C | 0.18 – 0.24 % | Primary hardener; highest among Mn-Cr grades |
| Manganese | Mn | 1.1 – 1.4 % | Hardenability and tensile strength |
| Silicon | Si | 0.15 – 0.35 % | Deoxidizer; minor strength contributor |
| Chromium | Cr | 1.0 – 1.3 % | Wear resistance, hardenability, carbide formation |
| Phosphorus | P | max 0.030 % | Controlled; excess P reduces toughness |
| Sulfur | S | max 0.030 % | Controlled; excess S causes hot shortness |
Why Carbon Content is the Key Differentiator
The carbon range of 0.18–0.24% is the defining characteristic that separates 21MnCr5 from its nearest alternative, 20MnCr5 (1.7147), which tops out at 0.22% C. This additional carbon produces a steeper carbon gradient from surface to core after carburizing, delivering:
- More reliable and consistent 60+ HRC surface hardness after carburizing and quenching
- A harder, deeper effective case — typically 0.5–1.5 mm depending on process parameters and section thickness
- Improved resistance to case crushing under high contact stress in cold forming applications
- Better hardenability for thicker cross-sections, ensuring uniform case depth through the part
- Marginally reduced machinability before heat treatment — a worthwhile trade-off for high-performance tooling
Complete Heat Treatment Process for 21MnCr5
21MnCr5 supports several distinct heat treatment routes. The steps below describe the complete sequence from open die forging through to the final hardened component, as executed in Jiangsu Liangyi's ISO 9001:2015 certified production workflow:
Forging
Open die forging or ring rolling while the steel is at forging temperature. Proper start and finish temperature control ensures a fine, uniform grain structure — the prerequisite for all subsequent heat treatments. Minimum reduction ratio of 3:1 is required; 5:1 or above is recommended for critical components.
Temperature: 1150 °C → 850 °C · Slow furnace or pit coolingSoft Annealing (pre-machining)
Reduces hardness to a machinable level before the component is machined to near-net shape. Heating and holding at temperature allows carbide redistribution, followed by slow controlled furnace cooling.
680–720 °C · Controlled furnace cooling · Result: ≤ 217 HBNormalizing (optional)
Refines grain structure and relieves residual forging stresses. Recommended for heavy-section parts or components subject to dynamic or cyclic loading in service.
880–920 °C · Air cooling · Result: ≤ 240 HBCarburizing (case enrichment)
The machined part is exposed to a carbon-rich atmosphere at elevated temperature. Carbon diffuses into the surface layer, creating a high-carbon case (typically 0.8–1.0% C at surface) over a lower-carbon, tougher core. This is the critical step that defines 21MnCr5's exceptional wear performance. Gas carburizing, pack carburizing, and vacuum carburizing are all applicable.
880–930 °C · Gas / pack / vacuum carburizing · Case depth: 0.5–1.5 mmQuenching (hardening)
After carburizing, the part is quenched rapidly to transform the austenitic case into hard martensite. Oil quenching is standard and minimizes distortion; water quenching achieves slightly higher hardness but increases dimensional change risk for complex geometries.
810–830 °C · Oil or water quenching · Surface: up to 62 HRCLow-Temperature Tempering
A mandatory final step to relieve quench stresses and stabilize the martensitic case against brittle fracture in service. The exact tempering temperature is chosen to deliver the required final hardness specification — see the chart below for precise values.
150–220 °C · Air cooling · Final surface: 58–62 HRCTempering Temperature vs. Final Surface Hardness
The chart below shows the direct relationship between tempering temperature and resulting surface hardness for 21MnCr5, post-carburizing and post-quenching. This is the most critical data for engineers specifying the final hardness range:
For cold forming dies and mold bases where maximum wear life is the priority, specify 180–200 °C tempering to maintain ≥ 60 HRC. For parts requiring a balance of hardness and impact toughness under cyclic loading (e.g. automotive powertrain shafts), 250–300 °C tempering (57–58.5 HRC) is typically the optimal range.
Mechanical Properties of 21MnCr5 (1.2162)
In addition to its surface hardness performance, 21MnCr5 provides reliable core mechanical properties after forging and heat treatment. The following values represent the normalized condition and form the basis for structural design calculations:
| Property | Symbol | Typical Value | Test Standard |
|---|---|---|---|
| Tensile strength | Rm | 700 – 900 MPa | ISO 6892-1 |
| Yield strength | Re | ≥ 450 MPa | ISO 6892-1 |
| Elongation | A5 | ≥ 18 % | ISO 6892-1 |
| Reduction of area | Z | ≥ 50 % | ISO 6892-1 |
| Impact toughness (Charpy V) | KV | ≥ 50 J at 20 °C | ISO 148-1 |
| Surface hardness (post-carburizing) | HRC | 60 – 62 HRC | ISO 6508-1 |
| Core hardness (post-carburizing) | HB | 300 – 420 HB | ISO 6506-1 |
The defining engineering advantage of 21MnCr5 is this simultaneous achievement: a martensitic surface at 60+ HRC capable of resisting abrasive and adhesive wear, while the bainitic/martensitic core retains sufficient ductility (≥50 J Charpy toughness) to absorb impact energy without brittle fracture. This combination — not achievable with through-hardened tool steels alone — makes it irreplaceable for high-load, high-wear applications.
Industrial Applications of 21MnCr5 Forged Parts
The combination of extreme surface hardness and resilient core toughness makes 21MnCr5 the preferred material specification across a broad range of precision engineering sectors. The following represent the principal applications where custom 21MnCr5 forged parts are routinely specified by engineers worldwide:
Cold Forming Tools & Dies
Punch tools, stamping dies, cold heading tools, burnishing dies, and die blocks. The 60+ HRC case resists progressive wear over high-volume production runs in fastener, gear, and precision parts manufacturing.
Plastic Injection Mold Bases
Mold bases, cavity blocks, and core inserts for thermoplastic and thermosetting processes. Excellent polishability, dimensional stability under repeated thermal cycling, and good machinability in the annealed condition.
Automotive Powertrain Components
Transmission shafts, gear blanks, pinion shafts, camshaft blanks, piston pins, and shift fork blanks for passenger vehicles, commercial trucks, and new energy vehicles (NEV). Essential for high-cycle fatigue resistance.
Hydraulic & Pneumatic Systems
Piston rods, valve spools, sleeve bushings, and cylinder liners for high-pressure systems. Hard carburized surface withstands high-frequency sliding contact; tough core absorbs hydraulic shock loads.
Mining & Construction Machinery
Bucket pins, track bushings, pivot shafts, and wear plates for excavators, bulldozers, and drilling equipment operating in high-impact, abrasive environments.
General Engineering Wear Parts
Guide columns, jig bushings, indexing pins, bearing housings, and structural components requiring a hard wearing mating surface combined with a tough, ductile cross-section.
21MnCr5 vs Similar Case Hardening Steel Grades
Selecting the right case hardening grade requires understanding how 21MnCr5 compares against the alternatives. The comparison below covers the grades most commonly evaluated against 21MnCr5 in engineering specifications:
| Grade | WNr | C % | Mn % | Cr % | Surface HRC | Best Application |
|---|---|---|---|---|---|---|
| 21MnCr5 | 1.2162 | 0.18–0.24 | 1.1–1.4 | 1.0–1.3 | 60–62 | Cold dies, mold bases, high-wear parts |
| 20MnCr5 | 1.7147 | 0.17–0.22 | 1.1–1.4 | 1.0–1.3 | 58–62 | Automotive gears & transmission shafts |
| 16MnCr5 | 1.7131 | 0.14–0.19 | 1.0–1.3 | 0.8–1.1 | 56–60 | Small gears, pins, general engineering |
| 18CrMo4 | 1.7243 | 0.15–0.21 | 0.5–0.8 | 0.9–1.2 | 58–62 | Heavy-duty gears, large-section crankshafts |
| 17CrNiMo6 | 1.6587 | 0.14–0.20 | 0.5–0.9 | 1.5–1.8 | 58–62 | Aerospace, large wind turbine gears |
Choose 21MnCr5 when ≥60 HRC surface hardness is mandatory: cold forming dies, punch tooling, mold bases. Choose 20MnCr5 for high-volume automotive gears and shafts where machinability and slightly lower hardness requirements are acceptable. Choose 17CrNiMo6 when Ni-enhanced core toughness is required for very large, heavily shock-loaded components such as wind turbine main shafts.
International Equivalent Grades for 21MnCr5 / 1.2162
Engineers and buyers working across international standards need to identify the closest regional equivalent. The table below provides the official cross-reference for the principal global standard systems:
| Standard System | Designation | Country / Region | Similarity Note |
|---|---|---|---|
| DIN EN 10084 | 21MnCr5 / 1.2162 | Europe (EU / Germany) | Reference standard — exact |
| AISI / SAE | 5120 | United States | Closest equivalent; slightly lower Cr |
| BS (British Standard) | 805M20 | United Kingdom | Closest equivalent |
| NF (French Standard) | 20MC5 | France | Near equivalent |
| JIS G4053 | SCr420 | Japan | Closest equivalent |
| GB (Chinese Standard) | 20CrMn | China (PRC) | Closest equivalent |
| UNI (Italian Standard) | 20MnCrS5 | Italy | Near equivalent |
| ГОСТ (Russian Standard) | 20ХН | Russia | Closest equivalent |
Grade equivalence is based on similar chemical composition and mechanical property targets. For safety-critical applications, always verify the specific composition limits and mechanical property requirements against your design specification. Do not rely solely on grade name matching across standards.
Forging 21MnCr5: Process Parameters & Available Shapes
Open die forging is the preferred manufacturing route for large, custom-geometry 21MnCr5 components. Forging not only shapes the material but actively refines the as-cast grain structure of the steel ingot — closing porosity, breaking up chemical segregation, and aligning grain flow along the part's principal stress axis. This produces mechanical properties consistently superior to bar stock or cast alternatives for the same composition.
Key Forging Process Parameters for 21MnCr5
- Start temperature: 1050–1150 °C — ingot must be fully and uniformly soaked before forging begins
- Finish temperature: Not below 850 °C — finishing below this risks cold working and surface cracking
- Reduction ratio: Minimum 3:1 overall; ≥ 5:1 recommended for critical applications to fully close original ingot porosity
- Post-forge cooling: Slow furnace cooling or controlled pit cooling to prevent thermal gradients, surface cracking, and internal stress buildup
- Annealing timing: Transfer to annealing furnace while temperature remains above 500 °C, or fully reheat before annealing cycle begins
Available Product Forms for 21MnCr5 / 1.2162 Forgings
Jiangsu Liangyi produces 21MnCr5 / 1.2162 in all standard open die forging shapes including bars, shafts, seamless rolled rings, hollow sleeves, die blocks, and discs — with individual piece weights from 30 kg to 30,000 kg. All products are manufactured to customer drawings and technical specifications. For the complete dimensional range, full shape catalog, surface treatment options, and product-level certification requirements, refer to the dedicated 21MnCr5 forged parts product page.
Quality Assurance & Documentation for 21MnCr5 Forged Parts
When sourcing 21MnCr5 forgings, the quality documentation package is as important as the physical parts. A properly certified batch of 1.2162 forging specifications and certifications from Jiangsu Liangyi includes the following complete set of traceable documents:
- EN 10204 3.1 Mill Test Certificate (MTC) — Full chemical analysis from the actual production heat, complete mechanical test results, and heat treatment records with traceable heat number. This is our standard document supplied with every order.
- Heat treatment certificate — Actual temperature-time curves, furnace identification number, cooling method, and hardness test results at multiple locations
- Ultrasonic Testing (UT) report — Per EN 10228-3 or customer acceptance criteria; confirms absence of internal flaws, cracks, and inclusions
- Magnetic Particle Testing (MT) report — Surface integrity verification per EN 10228-1
- Dimensional inspection report — With 3D CMM measurement records for complex geometries; all critical dimensions verified against drawing
- Metallographic examination report — Grain size rating, microstructure assessment, and inclusion rating per ISO standards
- Full traceability chain — Heat number linking every finished part back to the steel ingot melt, raw material analysis, and all intermediate process records
Always specify EN 10204 3.1 MTC as a minimum in your purchase order — this is our standard deliverable for every order. For aerospace, pressure vessel, or offshore applications requiring independent verification, EN 10204 3.2 certification by a third-party inspector (Bureau Veritas, SGS, TÜV Rheinland, or your nominated body) can be arranged at your cost and coordination. We fully cooperate with all customer-nominated inspectors. When reviewing heat treatment documentation, always request the actual temperature-time chart — it is more reliable than the certificate alone.
Why Trust This Information
Frequently Asked Questions About 21MnCr5 (1.2162) Steel
21MnCr5 (1.2162) is used for components requiring high surface wear resistance and tough core impact resistance simultaneously. Primary applications include: cold forming dies and punch tools; plastic injection mold bases and cavity blocks; automotive transmission shafts, gear blanks, and piston pins; hydraulic piston rods, valve spools, and sleeve bushings; mining machinery pins and bushings; and general engineering guide columns and indexing components. It is widely specified across Europe, North America, Japan, and China wherever DIN EN 10084 case hardening steels are used.
Yes. 21MnCr5 is the symbolic material name and 1.2162 is the Werkstoffnummer (material number) for exactly the same steel grade under DIN EN 10084:2008. Both designations appear on the same material standard and refer to the same chemical composition, mechanical properties, and heat treatment specifications. Always request that both designations appear on your Mill Test Certificate for full traceability.
After standard carburizing (880–930 °C) and quenching (810–830 °C), 21MnCr5 achieves 60–62 HRC surface hardness. Low-temperature tempering adjusts the final value: 180 °C tempering maintains ≥60 HRC; 250 °C gives 58.5 HRC; 300 °C gives 57 HRC; 400 °C gives 53.5 HRC; 500 °C gives 50.5 HRC. The core hardness is typically 300–420 HB with ≥50 J Charpy impact toughness, ensuring the part can withstand dynamic shock loads without brittle failure.
The closest AISI/SAE equivalent to 21MnCr5 (1.2162) is AISI 5120. Both have similar carbon (0.18–0.23%) and chromium content, though AISI 5120 has slightly lower Cr (0.70–0.90% vs 1.0–1.3% for 21MnCr5). Other international equivalents: JIS SCr420 (Japan), BS 805M20 (UK), NF 20MC5 (France), GB 20CrMn (China), UNI 20MnCrS5 (Italy). For US buyers sourcing from Jiangsu Liangyi, test reports can be issued against both DIN EN 10084 and the closest AISI equivalent standard simultaneously.
Both are DIN EN 10084 manganese-chromium case hardening steels with nearly identical manganese and chromium content. The key difference is carbon: 21MnCr5 (1.2162) has 0.18–0.24% C; 20MnCr5 (1.7147) has 0.17–0.22% C. This means 21MnCr5 achieves more reliably ≥60 HRC surface hardness and has marginally better hardenability for thicker-section parts. 20MnCr5 is the dominant automotive transmission grade prioritizing machinability in high-volume production; 21MnCr5 is preferred for cold forming dies, mold blocks, and any application where maximum surface hardness is the design requirement.
Our standard certification is EN 10204 3.1 Mill Test Certificate (MTC), supplied with every order. It covers: full chemical analysis from the actual production heat, complete mechanical test results, and heat treatment records with traceable heat number. For safety-critical applications (aerospace, pressure vessels, offshore), EN 10204 3.2 certification can be arranged by the customer through their nominated independent third-party inspector (Bureau Veritas, SGS, TÜV Rheinland, or others). We fully cooperate with all third-party inspectors. Additionally request: UT report (EN 10228-3), MT report (EN 10228-1), dimensional inspection report, and actual heat treatment temperature-time charts.
Reference pricing from ISO-certified manufacturer Jiangsu Liangyi starts from approximately USD 2.00 per kg for standard shapes (round bars, simple shafts, rings). Final pricing depends on part geometry and complexity, heat treatment requirements (annealing, Q+T, carburizing), dimensional tolerances, machining allowance, order quantity, and certification level required. Third-party (EN 10204 3.2) inspection arranged by customer may affect lead time. Contact sales@jnmtforgedparts.com with drawings for a precise quotation — detailed responses provided within 24 hours.
21MnCr5 has limited weldability due to its carbon equivalent. Welding without pre-heat and post-weld heat treatment (PWHT) risks hydrogen cracking and hard heat-affected zones. Pre-heat to 150–200 °C is the minimum requirement before any welding. PWHT at 600–650 °C should follow to temper the heat-affected zone. In most forging applications, welding is not part of the manufacturing process as components are machined to net shape. If welding is essential, consult a certified welding engineer for the procedure specification.
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