1.2767 vs 1.2083 – Composition, Heat Treatment, Properties, and Applications
แบ่งปัน
Table Of Content
Table Of Content
Introduction
Choosing between EN 1.2767 and EN 1.2083 is a common engineering decision when designing tooling, dies, or high-precision parts. Engineers, procurement managers, and manufacturing planners must balance competing priorities such as resistance to mechanical shock and fatigue versus surface finish and polishability. In practical terms, the primary contrast is that one grade is formulated to deliver higher bulk toughness and resistance to thermal/mechanical shock, while the other is optimized for high surface quality, fine carbide distribution, and superior polishability in finished tools.
These two EN Werkstoff numbers are frequently compared because they occupy adjacent roles in the tool-steel spectrum: one as a tougher, more ductile tool-steel family used where fracture resistance is critical; the other as a harder, high-chromium grade used where wear resistance and surface finish dominate the specification.
1. Standards and Designations
- EN: 1.2767, 1.2083 (Werkstoff numbers under the EN system).
- General classification: both are tool steels under EN tool-steel families (cold-work or hot-work / shock resistant categories depending on the sub-grade and heat-treatment condition).
- ASTM/ASME/JIS/GB: There is not always a single direct cross-reference to AISI/ASTM names for every EN number. Users should verify cross-reference tables from mill certificates or standards bodies for exact equivalences.
- Category:
- 1.2767 — typically associated with an alloy/tool steel designed for high toughness and shock resistance (used in tools subject to impact, presswork, or thermal cycling).
- 1.2083 — typically associated with a high-chromium cold-work tool steel variant optimized for wear resistance and polishability.
2. Chemical Composition and Alloying Strategy
| Element | 1.2767 (qualitative) | 1.2083 (qualitative) |
|---|---|---|
| C (Carbon) | Medium — supports hardenability but balanced to preserve toughness | Medium–High — contributes to hard carbides and high wear resistance |
| Mn (Manganese) | Low–Medium — deoxidation and slight strength control | Low–Medium — similar role, limited to avoid excessive hardenability |
| Si (Silicon) | Low — deoxidizer and strength stability | Low — deoxidizer; low content helps polishability |
| P (Phosphorus) | Trace/controlled | Trace/controlled |
| S (Sulfur) | Trace/controlled | Very low — low S improves surface finish |
| Cr (Chromium) | Medium — contributes to hardenability and tempering resistance | High — forms fine chromium carbides for wear resistance and polishability |
| Ni (Nickel) | Low–Medium — can be present to improve toughness | Low — not generally a key alloying element in highly polishable grades |
| Mo (Molybdenum) | Medium — improves hardenability and temper resistance | Low–Medium — refines carbides and improves temper stability |
| V (Vanadium) | Low–Medium — promotes fine carbide dispersion and toughness | Low — may be present in controlled amounts to refine carbides |
| Nb/Ti/B | Trace/used for microalloying if present | Trace/used to control grain size and improve carbide distribution |
| N (Nitrogen) | Trace | Trace |
Notes: - The table expresses typical alloying strategy qualitatively rather than exact percentages because specific chemistry varies by producer and sub-grade condition. The key alloying strategy difference is that 1.2767 emphasizes alloy content and heat-treatment response that preserve toughness and reduce sensitivity to crack initiation, while 1.2083 emphasizes chromium and carbide-forming elements that yield a fine, evenly distributed carbide population conducive to wear resistance and mirror polishing. - Control of impurities (P, S) is tighter in grades intended for high-surface-finish applications (better polishability demands lower S and non-metallic inclusions).
3. Microstructure and Heat Treatment Response
- 1.2767:
- Typical microstructure after appropriate heat treatment: tempered martensite or bainitic/tempered martensitic matrix with controlled carbide distribution. Alloying and heat-treatment recipes are optimized to retain toughness; tempered martensite with nanoscale alloy-carbides is a common goal.
- Heat-treatment response: responds well to preheating, quenching, and tempering cycles designed to balance hardness and toughness. Normalizing or subcritical annealing may be used prior to machining. Quench-and-temper gives a ductile, impact-resistant structure.
- 1.2083:
- Typical microstructure: martensitic matrix with a higher volume fraction of chromium-rich carbides (often relatively small and evenly distributed if processed correctly). The microstructure favors wear resistance and low-friction surfaces.
- Heat-treatment response: takes a high-hardness condition on quenching and tempering; nitriding or cryogenic treatment may be used to stabilize fine carbides and improve surface hardness. Overheating or coarse carbide growth reduces polishability, so tight control of thermal cycles is critical.
Manufacturing routes: - Normalizing refines grain size and is beneficial for both grades as a pre-treatment. - Quenching & tempering: gives final hardness and strength. In 1.2767, tempering is used to maximize toughness without sacrificing necessary strength; in 1.2083, tempering is controlled to produce high hardness for wear resistance while retaining enough ductility for service.
4. Mechanical Properties
| Property | 1.2767 (typical performance) | 1.2083 (typical performance) |
|---|---|---|
| Tensile Strength | Moderate–High in quenched & tempered condition; designed to resist fracture under load | High when fully hardened—focused on wear resistance |
| Yield Strength | Moderate — engineered to permit some plasticity before failure | High — less plastic deformation before yielding in hardened condition |
| Elongation | Relatively higher — better ductility | Lower — higher hardness reduces elongation |
| Impact Toughness | High — designed for shock resistance and resistance to crack propagation | Lower — carbide-rich microstructure reduces impact energy absorption |
| Hardness | Moderate to high depending on tempering (balanced for toughness) | Higher — optimized to achieve and retain high surface hardness |
Explanation: - 1.2767 will be chosen when impact toughness and resistance to sudden loading, chipping, or thermal cycling matter more than maximum achievable hardness. Its alloy mix and heat-treatment approach prioritize a tougher matrix. - 1.2083 will show higher hardness and wear resistance in service, offering better preservation of surface geometry and better mirror finish retention, but at the expense of bulk toughness.
5. Weldability
Weldability of tool steels depends strongly on carbon equivalent, hardenability, and microalloying. Two commonly used predictive formulas are:
$$CE_{IIW} = C + \frac{Mn}{6} + \frac{Cr+Mo+V}{5} + \frac{Ni+Cu}{15}$$
and
$$P_{cm} = C + \frac{Si}{30} + \frac{Mn+Cu}{20} + \frac{Cr+Mo+V}{10} + \frac{Ni}{40} + \frac{Nb}{50} + \frac{Ti}{30} + \frac{B}{1000}$$
Qualitative interpretation: - Higher chromium, molybdenum, and vanadium contents raise $CE_{IIW}$ and $P_{cm}$, indicating greater risk of hardenability-related cracking in weld heat-affected zones. - 1.2767, designed for toughness, often has alloy choices that moderate hardenability; preheat and controlled post-weld heat treatment (PWHT) are commonly required. - 1.2083, with higher chromium and carbide formers, tends to be less weldable without preheating, interpass temperature control, and post-weld tempering. In many cases, welding is avoided; machining or brazing/fusion welding specialist processes are used if joining is required. - For both grades, if welding is required, follow strict procedures: controlled preheat, low heat-input filler choices, controlled interpass temperature, and PWHT to reduce residual stresses and avoid HAZ cracking.
6. Corrosion and Surface Protection
- Neither grade is a stainless austenitic alloy; both are tool steels and will corrode in ambient and aggressive environments without protection.
- Common protections: painting, oiling, phosphating, or galvanizing for general corrosion protection; for tooling, corrosion-inhibiting coatings (PVD, nitride, or hard chrome plating) and maintenance oils are widely used.
- PREN formula is not typically applicable because neither grade is a stainless alloy where pitting resistance is a primary design metric:
$$\text{PREN} = \text{Cr} + 3.3 \times \text{Mo} + 16 \times \text{N}$$
- Use PREN only for stainless grades; for tool steels, evaluate environmental exposure and choose coatings or corrosion-resistant tool steels if needed.
7. Fabrication, Machinability, and Formability
- Machinability:
- 1.2767: generally more forgiving in machining and grinding because tempering to moderate hardness levels is common; better toughness reduces chipping during cutting.
- 1.2083: harder and more abrasive (carbide rich); machining in the fully hardened state is difficult—rough machining in annealed condition followed by final hardening and finish grinding/polishing is typical.
- Formability and bending:
- Both grades are not sheet-forming steels; they are shaped by machining, EDM, and grinding. If bending is involved, annealed conditions and stress-relief steps are used.
- Surface finishing:
- 1.2083 is easier to achieve and retain a mirror or high-luster surface due to fine carbide distribution and low inclusion content when processed correctly.
- 1.2767 requires more attention to grinding and polishing practice to avoid micro-chipping because the objective is to preserve bulk toughness.
8. Typical Applications
| 1.2767 — Typical Uses | 1.2083 — Typical Uses |
|---|---|
| Heavy-duty dies subjected to impact and thermal cycling (press tools, hot stamping) | Precision dies and molds that require high polish, such as optical molds, mirror finish tooling, and fine blanking dies |
| Punches and shear blades where shock resistance is critical | High-wear cutting edges and forming tools where surface finish and dimensional retention are essential |
| Components where fracture resistance and fatigue life are prioritized | Progressive-die inserts and parts that need long wear life plus superior surface finish |
| Structural tooling exposed to thermal gradients | Tools for decorative or visible components requiring blemish-free surfaces |
Selection rationale: - Choose 1.2767 when the tool is likely to see sudden loads, press-impact, or high thermal/ mechanical cycling where toughness and resistance to crack propagation override the need for a superlative surface polish. - Choose 1.2083 when the finished surface quality, dimensional stability under wearing contact, and resistance to abrasive wear are the primary drivers.
9. Cost and Availability
- Cost drivers: alloying elements (Cr, Mo, V), processing (tight impurity control, vacuum melting, powder metallurgy), and post-processing (hardening, cryogenic treatment, nitriding).
- Availability:
- Both grades are generally available from specialist tool-steel mills and distributors, but specific product forms (bars, pre-hardened plates, powder-metallurgy variants) vary by supplier.
- 1.2083 variants optimized for mirror finish may be a premium product due to tighter inclusion control and finishing; 1.2767 variants optimized for toughness may be more widely stocked in larger cross-sections for press-tool applications.
- From a procurement perspective, consider total cost of ownership: material cost + heat treatment + finish processing + expected life under operating conditions.
10. Summary and Recommendation
| Criterion | 1.2767 | 1.2083 |
|---|---|---|
| Weldability | Better (relatively), but still requires care | More challenging — higher risk of HAZ cracking |
| Strength–Toughness balance | Optimized for toughness and resistance to impact | Optimized for high hardness and wear resistance |
| Cost (typical) | Moderate — processing to preserve toughness | Moderate–High — may require finer processing for polishability |
Conclusion and selection guidance: - Choose 1.2767 if: the tooling or component must resist mechanical shock, chipping, or thermal cycling; if higher impact toughness and resistance to crack initiation are primary concerns; or when the application tolerates a good but not mirror-grade surface finish. - Choose 1.2083 if: surface finish, polishability, and wear resistance are the dominant requirements; when maintaining tight surface geometry under abrasive contact is critical; or when the final part demands a mirror or optical-quality finish and service conditions do not subject it to frequent impact loading.
Final note: exact performance depends strongly on the precise sub-grade chemistry, melting route, and heat-treatment cycle. For critical selections, request mill certificates, hardness and microstructure verification from suppliers, and perform application-level testing (fatigue, impact, polishing trials) before finalizing procurement.