NADCA #207-2025, formally titled "Special Quality Die Steel & Heat Treatment Acceptance Criteria for Die Casting Dies," now defines acceptance criteria across nine steel grades labeled A through I, a structural change from the A through G lineup carried in NADCA #207-2016 [S1][S2]. The 2025 revision adds Grade H (a modified 2367 with high vanadium) and Grade I (an H11 modified with increased carbon) to the published grade table [S1].
The document is sold by the North American Die Casting Association as a 2025 book publication and is also bundled inside the broader NADCA #229 volume, with member pricing listed at USD 75 against a non-member price of USD 150 [S1][S2]. Die casters and tool builders are told in the standard's statement of purpose to require a Certificate of Conformance with each piece of special quality die steel and with each furnace load of heat-treated steel [S1][S2].
What the standard actually tests on the steel
The material-quality section of NADCA #207 covers six test families: chemical composition, hardness range, microcleanliness levels, ultrasonic soundness, microstructure, and impact strength capability [S1][S2]. For H13 specifically, this maps to the long-standing Chromium-Molybdenum-Vanadium matrix used in hot-work tooling, with typical Chromium at 5.0%, Molybdenum at 1.5%, and Vanadium at 1.0% per current H13 procurement guidance [S5].
The heat-treatment section is equally prescriptive and locks down furnace requirements, pre-heat / austenitize / temper temperatures and times, quenching practice, post-quench microstructure, plus hardness and impact testing on every load [S1][S2]. In the 2025 revision, the definitions for "maximum controlling cross section" used to size heat-treat loads and the thermocouple placement rules have been tightened, and the Certificate of Conformance has been shortened: Sections "S" and "T" were removed because that testing is performed downstream by the end user or testing facility [S1].
Grade structure: from A-G (2016) to A-I (2025)
Grade A is the entry tier, designated as Premium H13, and is offered as Class 1 or Class 2 for applications where a lower material and heat-treatment quality is acceptable [S1][S2]. Grade B is labeled "Superior Grade H13" and opens the special-quality band, while Grades C through G cover other tool-steel chemistries in the 2016 lineup [S2].
The 2025 edition inserts Grade H (a modified 2367 with high vanadium content for improved temper resistance) and Grade I (an H11 base with elevated carbon for higher core hardness) into the published grade list, expanding the special-quality menu without removing the existing A-G tiers [S1]. Class 1 and Class 2 designation still apply across the grade table, controlling the depth of testing and certification required on each heat [S1][S2].
Why H13 is the default die material for HPDC, and where it fails
In high-pressure die casting of aluminum, magnesium, and zinc alloys, the die cavity is repeatedly filled with molten metal above 650°C (1200°F) and then water-lubricant cooled, a thermal cycle that destroys ordinary cold-work or plain carbon steels within a few hundred shots [S5]. H13's 5% Chromium gives deep hardenability in forged blocks exceeding 600 mm in thickness, 1.5% Molybdenum supplies the "red hardness" needed to resist softening at operating temperature, and 1.0% Vanadium forms stable carbides that block grain growth and resist wear [S5].
Even with the right chemistry, the dominant failure mode is heat checking, a network of microscopic surface cracks driven by alternating thermal expansion and rapid water cooling, which then propagates into gross cracking and unscheduled die changeover [S5]. Specifying H13 to NADCA #207 is the procurement-side answer to that failure mode, because the standard gates melt cleanliness, microstructural banding, and Charpy impact energy before the block ever sees molten aluminum [S1][S2].
Procurement signals from the 2025 supply chain
European steelmaker Bonomi Acciai announced on 2025-10-07 that its Thermodur® EFS Superclean family is NADCA #207 approved, listing Thermodur 2343 EFS Superclean, 2344 EFS Superclean, 2367 EFS Superclean, E38K Superclean, and E40K Superclean against the standard's grade table [S3]. The approval is positioned as a procurement short-cut: a mill that has already passed the audit ships block with the test data, microcleanliness plots, and Charpy values pre-formatted to the Certificate of Conformance, which compresses incoming inspection time at the die shop [S3].
Buyers should still verify the heat-specific data: a NADCA #207 certificate travels with each piece of steel and each furnace load, and a missing or generic mill certificate is grounds for rejection before any machining begins [S1][S2]. The 2025 edit removing Sections "S" and "T" from the Certificate of Conformance means impact and ultrasonic retest data now arrive from the end user's test house rather than the mill, so receiving inspection needs a downstream test plan to close that loop [S1].
Comparison: NADCA #207-2025 grades against selection criteria
For an engineer choosing between grades, four decision criteria dominate: required die life (shots before heat-check rework), maximum die-block thickness, alloy family, and minimum Charpy impact at the as-tempered hardness. Grade A Premium H13 is the lowest-cost option and fits short-run or prototype tooling where failure after a few thousand shots is tolerable [S1][S2]. Grade B Superior H13 is the workhorse for production aluminum HPDC dies, with the same nominal H13 chemistry but tighter microcleanliness and impact floors [S1].
Grade C through G cover alternative chemistries (H11, H21, H10, modified H13, and so on) for specific wear, toughness, or thermal-conductivity trade-offs [S2]. Grade H, the new 2025 high-vanadium 2367 variant, targets large die blocks for components such as structural castings where temper resistance matters more than raw H13 toughness, while Grade I, the carbon-enriched H11, fits inserts and cores that need higher surface hardness without sacrificing through-thickness toughness [S1][S3]. Buyers running magnesium or zinc die casting at lower melt temperatures can usually stop at Grade B and divert the cost of Grade H or I into better cooling layouts, while large-tonnage aluminum structural programs should spec Grade H for the die base and Grade I for cores subject to the highest thermal cycling [S1][S3][S5].
Scope limits and what NADCA #207 does not cover
NADCA #207 is explicitly not intended for all die casting applications; it targets high-volume production and critical-performance dies, leaving lower-tier tooling to commercial Premium H13 with lighter documentation [S1][S2]. The standard also stops at material and heat treatment: it does not specify die design, cooling layout, ejector layout, or welding-procedure qualification beyond a brief weld-repair procedure in the appendix [S1][S2].
For the broader component specification (dimensional tolerances, alloy chemistry, surface finish), specifiers still need the NADCA Product Specification Standards for Die Castings, whose 2015 ninth edition runs 272 pages and is the reference for cross-alloy tolerance and metallurgical data [S4]. For the die steel itself, NADCA #207-2025 is the controlling document, and its 2025 changes (Grade H, Grade I, tightened cross-section definitions, trimmed Certificate of Conformance) are the deltas a receiving inspector needs to know about [S1].
Selection checklist for a die shop buying H13 to NADCA #207-2025
First, write the grade letter (A, B, C, D, E, F, G, H, or I) and the class (1 or 2) into the die-steel purchase order, not just "H13 to NADCA #207," because the grade letter drives chemistry and the class drives the depth of certification [S1][S2]. Second, require the mill Certificate of Conformance on each block, with the chemistry, hardness, microcleanliness, ultrasonic, and Charpy data tied to the heat number [S1].
Third, require a separate heat-treat Certificate of Conformance on each furnace load, recording austenitizing temperature, quench medium, temper temperature and time, and post-temper hardness and Charpy, with thermocouple locations that respect the 2025 maximum-controlling-cross-section rules [S1]. Fourth, for new large-tonnage HPDC dies, run a sample coupon through a metallurgical lab to verify Charpy impact at the working hardness, since mill data may be taken at a different cross section than the actual die casting die [S1][S3]. Fifth, for shops running multi-cavity die casting machine setups where a single heat-treat batch feeds several dies, confirm the furnace load size still meets the controlling-cross-section definition or the as-tempered impact values will not transfer from coupon to production block [S1]. Buyers also need to align their die steel callout with the NADCA #207 weld-repair appendix if any EDM-damaged zones will be rebuilt by welding rather than replaced, because the appendix governs pre-heat, filler, and post-weld temper windows [S1][S2].
Two signals to watch over the next quarter: NADCA's roll-out of any redline or errata on the 2025 edition, particularly around the new Grade H and Grade I chemistry limits, and any new mill announcements of #207-2025 approval following Bonomi Acciai's 2025-10-07 disclosure, since each new approval expands the auditable supply pool for shops that have been bottlenecked on a single qualified source [S1][S3].
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