ISO 11124-7:2025

Overview

ISO 11124-7:2025 defines specifications for high chromium white cast iron grit used as metallic blast-cleaning abrasives. The standard covers abrasives supplied in the new condition for blast-cleaning processes, specifying particle size grades, hardness and density limits, metallographic structure, chemical composition and allowable defects. It is intended to ensure consistent performance and safe, traceable supply of grit for both static and site blasting operations.

Key topics and technical requirements

• Particle size and grade designations: Screening specifications are given for grit grades (e.g., G170 to G004) with nominal particle sizes expressed as a three-digit code.
• Hardness: At least 90% of particles must fall within the standard hardness range of 500 HV to 850 HV; alternative hardness ranges can be specified (minimum ~140 HV spread).
• Apparent density: Minimum 7.0 g/cm³ (≈7 000 kg/m³).
• Defects and quality limits:
  • Shot content: max 10% for grades G060 and below; max 15% for G085 and above.
  • Cracks: max 40%.
  • Total defects: max 40%.
  • Foreign matter: mass fraction max 1%.
• Metallographic structure: High chromium white cast iron microstructure with chromium carbides in martensitic and/or austenitic matrix; no more than 15% of particles with undesirable microstructure.
• Chemical composition: Carbon 1.5–3.5%, Chromium 25–35%, Silicon ≤4%, Manganese ≤2%.
• Moisture: max 0.2% mass fraction.
• Sampling and testing: Procedures reference the ISO 11125 test-method series (particle size, hardness, density, defects, foreign matter, moisture).
• Identification & traceability: Product designation format (e.g., Abrasive ISO 11124 M/HCCI/G118/500-850 HV), batch marking and lot traceability are required on packaging.
• Scope limitation: Requirements apply only to abrasives in the new condition - not during or after use.

Applications and users

ISO 11124-7:2025 is relevant for:

• Abrasive manufacturers producing high chromium white cast iron grit.
• Surface preparation contractors and blast cleaning operators specifying abrasives for static or site blasting.
• Procurement, QA/QC engineers and inspectors who verify conformity to particle size, hardness, composition and defect limits.
• Specifiers and asset owners seeking abrasives optimized for recovery/re-use, including work on non‑ferrous substrates and components where no subsequent coating is applied.

Practical benefits include improved consistency of blast-cleaning performance, safer reuse/recovery of abrasive, and clear labelling for traceability. Note: when blasting dissimilar metals, users should consider the risk of galvanic corrosion.

Related standards

• ISO 11125 series (Parts 1–7) - test methods for metallic blast-cleaning abrasives
• ISO 11124 series - other metallic abrasive specifications
• ISO 439, ISO 629, ISO 9556, ISO 10138 - elemental analysis methods referenced by ISO 11124-7

Keywords: ISO 11124-7:2025, high chromium white cast iron grit, metallic blast-cleaning abrasives, particle size, hardness, blast-cleaning, abrasive recovery, metallographic structure, chemical composition, traceability.