Overview
ISO 8075:2025 - "Aerospace - Surface treatment of hardenable stainless steel parts" defines technical procedures and quality requirements for cleaning, finishing and passivation of martensitic, precipitation‑hardening and maraging stainless steels used in aerospace (examples: 400 series, 17‑7PH, 17‑4PH, 15‑5PH, AM350, AM355, PH15‑7Mo, PH13‑8Mo, Custom 450/455). The standard focuses on practical methods to remove organic and inorganic contaminants and to obtain suitable corrosion resistance prior to non‑destructive inspection (NDI) or subsequent coatings.
Key topics and technical requirements
- Scope and materials: Applies to martensitic, precipitation‑hardening and maraging stainless steel parts and covers surface cleaning, finishing and passivation before NDI.
- Cleaning methods: Specifies degreasing approaches such as solvent cleaning, high‑temperature steam, emulsion cleaning and alkaline degreasing (including ultrasonic aid).
- Scale and oxide removal: Defines conditioning and pickling processes with approved chemical formulations (examples in the standard include KMnO4 / NaOH / Na2CO3 and high‑alkali / NaNO2 solutions) and guidance on minimal exposure times to avoid metallurgical damage.
- Stress relief: Prescribes stress‑relief bake parameters for high‑hardness parts (e.g., parts > HRC 36: ~190 °C ± range for minimum hours) and alternative baking for carburized or specific 440‑series steels.
- Passivation & corrosion control: Requires final surface passivation unless a coating is specified; gives water and rinse quality limits (total dissolved solids ≤ 100 mg/kg, chloride ≤ 12 mg/kg, pH 5.5–8.0).
- NDI preparation: Advises treatments before magnetic particle or penetrant inspections (e.g., degreasing/descaling; pickling when penetrant inspection is used).
- Quality assurance: Covers batch acceptance (appearance, corrosion resistance), process control and qualification tests, solution control/analysis, inspection and approvals.
- Packaging and delivery: Includes requirements for packaging and delivery to preserve treated surfaces.
Applications and users
ISO 8075:2025 is intended for:
- Aerospace manufacturers and OEMs handling hardenable stainless steel components.
- Surface‑treatment shops, chemical suppliers and heat‑treatment facilities that prepare parts for NDI or coating.
- Quality and inspection engineers responsible for corrosion resistance, passivation and NDI readiness of flight‑critical hardware.
Practical benefits: improved corrosion performance, repeatable cleaning/passivation procedures, clearer NDI preparation, and documented process/solution control for aerospace acceptance.
Related standards
- ISO 9227 - Corrosion tests in artificial atmospheres (salt spray) - referenced for corrosion assessment.
Keywords: ISO 8075:2025, aerospace surface treatment, passivation, hardenable stainless steel, martensitic, precipitation hardening, maraging, pickling, degreasing, corrosion resistance, non‑destructive inspection.