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PD ISO TR 10809 — Cast Irons Materials and Welding Technical Reports (ISO/TR 10809 Series)
Cast Irons — ISO/TR 10809 Series（Part 1 Materials and Properties for Design / Part 2 Welding）
🏭 PD ISO/TR 10809 is a BSI Published Document implementing ISO/TR 10809 in the UK, developed by Technical Committee ISE/111 (Steel castings and forgings). Cast iron is one of the most widely used casting alloys, spanning grey cast iron, ductile (spheroidal graphite) iron, compacted graphite iron, malleable iron, austempered ductile iron, and special abrasion-resistant and corrosion-resistant grades. This batch covers two technical reports: Part 1 (Materials and properties for design) systematically answers “why use cast irons and how to select them”, while Part 2 (Welding) provides metallurgical and process guidance for welding cast irons. The two complement each other, forming a complete knowledge chain from material selection and design to manufacture and repair.
💡 The cast iron family has very different “personalities”: grey cast iron excels in damping and thermal conductivity but has low strength; ductile iron combines strength and toughness; compacted graphite iron balances strength and thermal conductivity. Choosing the right cast iron type is a decisive step in mechanical design.
1. Series Background and Positioning 📌
Cast irons are widely used in automotive, machine tools, piping, pumps/valves, and mechanical base parts because of excellent casting fluidity, low cost, and diverse property combinations. However, the cast iron family is large; different graphite forms and matrix structures produce very different mechanical and physical properties. In addition, the standardisation of cast irons has been continuously updated in recent years, with changes to material grade designations, which can confuse engineers during selection.
ISO/TR 10809 was developed to clarify these engineering questions: Part 1 starts from “why use cast irons”, introduces the advantages and disadvantages of each type and its application scenarios, and gives selection and design guidance; Part 2 specifically addresses the process-prone topic of welding cast irons, giving metallurgical background, suitable welding processes, and process requirements. The UK versions are published by BSI as Published Documents for citation in engineering design, procurement, and manufacturing.
⚠️ Cast iron grade systems change with standardisation updates: citing old grades or confusing the correspondence between different standards can result in materials that do not meet design requirements. Always select based on the currently valid material standards (e.g. ISO 185, ISO 1083, ISO 16112).
2. Series File List 📋
The PD ISO/TR 10809 series technical report files covered in this batch are listed below.
| Standard Number | Part Subject | Year | Core Content |
|---|---|---|---|
| PD ISO/TR 10809-1:2009 | Materials and properties for design | 2009 | Characteristics and selection rationale of each cast iron type, metallurgy, design and usage notes |
| PD ISO/TR 10809-2:2011 | Welding | 2011 | Cast iron metallurgy, suitable welding processes, preheating, and post-weld treatment requirements |
3. Materials and Properties for Design (Part 1) 🔧
Part 1 opens with “why use cast irons”, introducing the application value of each type of cast iron:
- Grey cast iron: characterised by flake graphite, excellent damping and thermal conductivity, low cost; widely used for machine tool beds, brake discs, and engine blocks.
- Ductile (spheroidal graphite) iron: characterised by nodular graphite, significantly better strength and toughness than grey iron; used for crankshafts, hubs, and pipes in load-carrying parts.
- Compacted graphite iron: vermicular graphite, strength between grey and ductile iron, combining good thermal conductivity and thermal fatigue resistance; used for engine blocks and cylinder heads.
- Malleable iron: annealed for ductility; used for thin-wall small parts and pipe fittings.
- Austempered ductile iron (ADI): austempering gives a high-strength, high-toughness combination; used for gears and transmission parts.
- Abrasion-resistant and austenitic cast irons: for wear applications and heat/corrosion-resistant service (e.g. Ni-Resist) respectively.
After introducing each type, Part 1 also gives metallurgy fundamentals, standardisation updates, and design/application cautions, helping designers map material properties to part functions.
✅ Suggested selection logic: first define the service function of the part (load, damping, heat conduction, wear, corrosion) → determine the key performance indicators → match candidate types in the cast iron family → verify mechanical properties against grade standards → consider casting process and economy before finalising the material.
4. Welding (Part 2) 🔥
Welding cast iron has special metallurgical difficulties: cast iron has high carbon content and high brittleness, so welding easily produces white iron, hard-brittle structures, and cracks — especially grey and ductile irons require careful process control. Part 2 gives systematic welding guidance:
- Cast iron metallurgy: explains how chemical composition, graphite form, and matrix structure affect weldability, and how heat input and cooling rate change the fusion-zone structure.
- Suitable welding processes: describes the suitability of oxy-acetylene gas welding (311), arc welding (1), gas-shielded metal arc welding (13/14), submerged arc welding (12), plasma arc welding (15), electron beam welding (511), and pressure welding processes (4) for cast iron.
- Preheating and interpass temperature: explains the role of preheating, slow cooling, and post-weld holding in reducing cracking tendency, giving the concept of preheat temperature ranges for common cast irons.
- Filler selection and post-weld treatment: presents selection principles for nickel-based, iron-based, and other fillers, plus notes on post-weld machining, stress-relief treatment, and defect repair welding.
Cast iron welding is mainly used for defect repair, assembly joining, and remanufacturing; mastering the correct process significantly improves repair quality and component life.
🚨 Cast iron must be adequately preheated before welding and the cooling rate controlled, otherwise white iron and cracks readily form in the fusion zone. When repairing critical load-carrying cast iron parts (e.g. crankshafts, cylinder blocks), develop and qualify a welding procedure specification (WPS) per the Part 2 guidance rather than welding by experience alone.
5. Engineering Practice Applications 🛠️
- Material selection in mechanical design: designers use Part 1 to choose the material type and grade in the cast iron family that matches the part’s function.
- Castings procurement and acceptance: procurement personnel verify grade, mechanical properties, and metallographic requirements against current material standards, avoiding confusion between old and new grades.
- Castings defect repair: foundries develop repair welding procedures per Part 2 to fix defects such as sand holes and shrinkage cavities, reducing scrap rate.
- Remanufacturing of in-service equipment: build-up welding and machining restore worn or damaged cast iron parts, extending equipment life.
A typical application path: identify part function and loads → choose cast iron type and grade per Part 1 → design the casting and set acceptance requirements → cast and inspect → if defects or repairs are needed, develop and implement a welding repair procedure per Part 2.
6. Frequently Asked Questions ❓
❓ Q: Why is grey cast iron prone to cracking during welding?
A: Grey cast iron has high carbon content and high brittleness; on rapid cooling, the fusion zone easily forms hard-brittle structures such as white iron (cementite) and martensite, and the shrinkage stress cannot be absorbed by plastic deformation, so cracking occurs. Preheating, slow cooling, and suitable fillers control this.
A: Grey cast iron has high carbon content and high brittleness; on rapid cooling, the fusion zone easily forms hard-brittle structures such as white iron (cementite) and martensite, and the shrinkage stress cannot be absorbed by plastic deformation, so cracking occurs. Preheating, slow cooling, and suitable fillers control this.
❓ Q: Is the weldability of ductile iron the same as grey cast iron?
A: Not exactly. Ductile iron, with nodular graphite and a mostly ferritic/pearlitic matrix, has different sensitivity to the weld thermal cycle and usually higher demands on post-weld properties; both need tailored procedures, but filler and preheat strategy differ.
A: Not exactly. Ductile iron, with nodular graphite and a mostly ferritic/pearlitic matrix, has different sensitivity to the weld thermal cycle and usually higher demands on post-weld properties; both need tailored procedures, but filler and preheat strategy differ.
❓ Q: Does ISO/TR 10809 prescribe mandatory mechanical property limits for cast irons?
A: No. It is a technical report providing selection and welding guidance; specific mechanical properties and acceptance requirements are set by the material product standards (ISO 185, ISO 1083, etc.) and contracts.
A: No. It is a technical report providing selection and welding guidance; specific mechanical properties and acceptance requirements are set by the material product standards (ISO 185, ISO 1083, etc.) and contracts.
🔍 Q: Why is ADI (austempered ductile iron) so strong?
A: ADI obtains an ausferritic matrix (acicular ferrite + carbon-enriched austenite) through austempering, with a dense structure and excellent combined strength and toughness; its strength can reach about twice that of ordinary ductile iron, suiting gears and other heavy-load transmission parts.
A: ADI obtains an ausferritic matrix (acicular ferrite + carbon-enriched austenite) through austempering, with a dense structure and excellent combined strength and toughness; its strength can reach about twice that of ordinary ductile iron, suiting gears and other heavy-load transmission parts.
📋 Q: What is the relationship between the UK editions and the ISO originals?
A: PD ISO/TR 10809-1:2009 and PD ISO/TR 10809-2:2011 are respectively the UK implementations of ISO/TR 10809-1:2009 and ISO/TR 10809-2:2011, technically identical in content, published by BSI for citation in the UK market.
A: PD ISO/TR 10809-1:2009 and PD ISO/TR 10809-2:2011 are respectively the UK implementations of ISO/TR 10809-1:2009 and ISO/TR 10809-2:2011, technically identical in content, published by BSI for citation in the UK market.