ADI Casting Process
Who this helps: Design Engineers / Buyers planning ADI (austempered ductile iron) parts—gears, sprockets, arms and high-load housings—who need repeatable strength–fatigue with sane cost.
What you’ll get: a clear ADI casting process map from melt to austemper, grade–temperature logic, section-size & transfer-time rules, quality gates you can run at PPAP, copy-paste drawing notes, plus internal links for deeper dives.
Prepared by YB Metal Solution. Share your drawing via /rfq—YB Metal will return a part-specific ADI grade choice + cycle window, section review and pilot test plan.
Author: YB Metal Solution Engineering Team (hereafter YB Metal)
Table of contents
- What the ADI casting process covers
- Step-by-step flow: from melt to austemper
- Grades vs hold temperature (how properties are set)
- Section size, transfer time & chemistry nudges
- Quality gates & acceptance (PPAP-ready)
- Machining, distortion & coating notes
- What to put on the drawing
- What YB Metal delivers
- FAQs
What the ADI casting process covers
ADI = ductile iron casting + austempering heat treatment.
The casting route (green/resin/shell) sets soundness, CT grade and machining stock. The austempering cycle converts a nodular-iron matrix into ausferrite (acicular ferrite + high-carbon austenite), enabling high strength–fatigue with useful toughness.
Quick primer: Open ADI Guide
Step-by-step flow: from melt to austemper
Melt → treat → inoculate (make a sound DI base)
- Stable Mg treatment and inoculation to achieve nodularity & nodule count appropriate for the section map.
- Pick the molding process by geometry/throughput:
- Green Sand Casting
- Resin vs Green Sand
- Shell Molding for Thin-Wall
Austenitize
Typical 840–920 °C (1545–1690 °F) with soak long enough to homogenize carbon and dissolve pearlite/carbides.
Quench/transfer above Ms
Rapid transfer into the isothermal bath (salt/alkaline) above Ms; minimize delay to avoid pearlite formation—especially on heavy sections.
Isothermal hold (austemper)
- Hold ≈260–380 °C (500–715 °F) until transformation to ausferrite completes.
- Lower hold → higher strength, lower ductility.
- Higher hold → lower strength, higher ductility.
Rinse, stabilize (if specified), inspect
Clean; optional stabilization/temper per control plan. Maintain heat-treat lot traceability to the casting heat.
Process window & controls: Austempering Cycle—Quality Gates
ASTM A897 – Austempered Ductile Iron Castings (official)
EN 1564 – Ausferritic spheroidal graphite cast irons (BSI official catalogue)
Grades vs hold temperature (how properties are set)
Choose the grade by load case & section size; confirm acceptance on the drawing/PO.
| Hold band tendency | ASTM A897 grade examples | What it suits |
|---|---|---|
| Lower (≈260–320 °C / 500–610 °F) | 1200-850-04, 1400-1100-02 | Gears/chain wheels, thin high-load links |
| Mid (≈300–340 °C / 572–644 °F) | 1050-750-07 | Sprockets, housings with high strength |
| Higher (≈330–380 °C / 625–715 °F) | 900-650-09, 750-500-11 | Brackets needing more ductility/impact |
Cross-standard notes: ADI Standards: ASTM A897 vs EN 1564
Selection map: ADI Grade Selection (Strength–Ductility)
Section size, transfer time & chemistry nudges
Section (t-band) governs achievable grade; heavier sections require short transfer time and often Ni/Cu/Mo additions.
Respect minimum walls for the ductile-iron base: Minimum Wall for Ductile Iron
Engineer directional solidification (risers/chills) at T/Y/X junctions to eliminate shrinkage before heat treatment: Fix Shrinkage Porosity
Confirm coupon strategy (separately cast/attached / from casting) early; it affects reported properties.
Corrosion choices: Coatings vs Material
Quality gates & acceptance (PPAP-ready)
Metallurgy
- Nodularity % per spec; ausferrite present, no free pearlite (unless allowed).
- Hardness band per grade (informational unless used as acceptance).
Mechanical:
- Tensile (Rm/Rp0.2/A%) per A897/EN 1564 grade; impact if required.
Dimensional:
- CT per ISO 8062; keep machining stock for critical faces.
- ISO 8062 CT Grades
- Open GD&T Guide
Documentation：
- PPAP/FAI: tensile/hardness tables, metallography photos (ausferrite micrographs), CMM FAI on datum stack.
Cycle guidance & QA: ADI Process Window
Machining, distortion & coating notes
- Machinability: ADI cuts tougher than DI—use robust carbide, edge prep, and coolant strategy; see Machinability: Gray vs Ductile Iron —
/machinability-gray-vs-ductile-iron-tool-life-coolant - Distortion: fixture during heat treatment and machining; for big housings reference Heat-Treatment Distortion Control
- Corrosion: ADI ≈ DI—pick stacks per environment: Corrosion—Coatings vs Material Choices
What to put on the drawing
Material & heat treatment
Material: ASTM A897 Grade 1050-750-07 (or EN 1564 EN-GJS-1050-6, t ≤ 30 mm).
Coupons: [separately cast / attached / from casting] — state in PO.
Austempering: Hold 300–330 °C (572–626 °F) above Ms to full ausferrite; no pearlite allowed.
Hardness: 302–375 HBW (informational unless used for acceptance).
Casting & dimensional:
Casting tolerances per ISO 8062 (CT grade by size band). Maintain machining stock per control plan.
Provide riser/chill plan for heavy junctions; avoid isolated pads.
QA (pilot & series):
Provide tensile (Rm/Rp0.2/A%), HBW, metallography (nodularity %, ausferrite check), and CMM FAI on datums. Record transfer time and bath setpoint per lot.
- Machining: carbide inserts, control heat; ADI is tougher than DI—optimize speeds/feeds and tool edge prep. Reference: Machinability: Gray vs Ductile Iron
- Distortion: fixture for stability; for large housings, see Heat-Treatment Distortion Control
- Coating: ADI ≈ DI for corrosion; pick stack & DFT by environment: Coatings vs Material
- Welding: generally not recommended; if allowed, qualify and consider re-austempering.
What YB Metal delivers
YB Metal Solution quotes with an ADI casting process plan attached:
- Grade decision matched to your section map & load case (A897 ⇆ EN 1564).
- Cycle window: austenitize temperature, hold band, transfer-time limit, bath medium.
- Chemistry nudges (Ni/Cu/Mo) for heavy sections with cost/lead-time impact.
- Pilot evidence pack: tensile/hardness tables, metallography (ausferrite photos), optional impact, and CMM FAI on critical features.
Need a plan for your part? Upload your drawing at /rfq—we’ll return recommendations and a quote.
FAQs
CTA — specify with proof, not guesses
Pick ADI on purpose—with the right grade, section plan and cycle window—then prove it with a data-backed pilot. Upload your drawing to /rfq and YB Metal will send a grade plan, cycle, and quotation.