Overview - ISO 5922:2005 (Malleable cast iron)
ISO 5922:2005 specifies mechanical and testing requirements for two types of malleable cast iron used in castings: whiteheart (JMW) and blackheart (JMB) malleable cast iron. The standard covers classification by mechanical properties measured on separately cast, heat‑treated test pieces and applies only to castings produced in sand moulds or moulds of comparable thermal diffusivity.
Example designation format: ISO 5922/JMW/400-5 (type JMW, minimum tensile strength 400 N/mm² and minimum elongation 5% on a 12 mm test piece).
Key topics and technical requirements
- Types covered: whiteheart (decarburized heat treatment) and blackheart (non‑decarburizing heat treatment), with subtypes (ferritic/pearlitic) for blackheart.
- Mechanical property grades: Tables give minimum tensile strength (Rm), elongation (A%), optional 0.2% proof strength (Rp0.2) and informative Brinell hardness (HBW) ranges for each grade and test‑piece diameter.
- Designation and ordering: Formal designation rules (ISO/TR 15931 based), and purchaser-specified grade plus any special requirements at order acceptance.
- Manufacture: Chemical composition, heat treatment and production methods are at the manufacturer’s discretion provided the final product meets the specified properties. For improved impact resistance, phosphorus should not exceed 0.10%.
- Sampling and test pieces: Test pieces must be separately cast in sand moulds during the same production run and heat treated identically to the castings. Choice of test‑piece diameter should represent relevant casting wall thickness.
- Test methods:
- Tensile testing per ISO 6892 using unmachined test pieces.
- Brinell hardness per ISO 6506‑1 (on tensile piece or casting).
- Impact testing (when requested) per agreement; guidance available referencing ISO 148 (Charpy).
- Weldability guidance: Whiteheart grades can be welded with proper procedures; JMW/360‑12 recommended where post‑weld heat treatment should be avoided. For thickness > 8 mm, post‑weld heat treatment is recommended.
Applications and practical use
- Use ISO 5922 when specifying material grades for machinery components, valves, fittings, gears, and other small to medium castings requiring controlled mechanical properties of malleable iron.
- Helpful for foundries, casting designers, procurement teams, quality laboratories and testing houses to:
- Select appropriate malleable cast iron grade for strength, ductility or pressure‑tightness.
- Define sampling, testing and acceptance criteria in purchase orders and contracts.
- Guide heat treatment and post‑weld procedures to meet performance targets.
Related standards
- ISO 6892 - Tensile testing of metallic materials
- ISO 6506‑1 - Brinell hardness test
- ISO 148 - Charpy impact test (V‑notch)
- ISO/TR 15931 - Designation system for cast irons and pig irons
- ISO 945 - Graphite forms (referenced for temper carbon)
Keywords: ISO 5922, malleable cast iron, whiteheart, blackheart, tensile strength, Brinell hardness, test pieces, sand moulds, casting standards.
