ISO 26910-1:2023

Overview - ISO 26910-1:2023 (Springs - Shot peening - Part 1: General procedures)

ISO 26910-1:2023 specifies general requirements and procedures for applying shot peening to springs to improve resistance to fatigue and stress corrosion cracking. The standard focuses on introducing compressive residual stresses in surface layers through controlled peening, and establishes common definitions, measurement methods and process controls to ensure repeatable, verifiable results across the spring industry.

Key topics and technical requirements

• Scope and purpose: Defines the intent of shot peening for springs - primarily to enhance fatigue life and reduce stress corrosion cracking by work hardening and compressive residual stresses.
• Terms and definitions: Standardizes vocabulary (e.g., shot peening, peening media, Almen strip, Almen arc height, saturation time, coverage, peening intensity).
• Modes of peening: Describes allowable modes including ordinary peening, multi-stage peening, stress peening, hot peening, heavy peening, and fine peening.
  • Ordinary peening: Almen arc height typically between 0.15 mm and 0.6 mm (A).
  • Heavy peening: Almen arc height > 0.6 mm (A).
  • Fine peening: Almen arc height < 0.15 mm (A).
• Process conditions to specify: Type and size of peening media, desired Almen arc height (with Almen strip class), coverage (area and location), and processing time (or multiplier of saturation time).
• Peening media: Categorizes media types (conditioned cut wire, cast steel shot, glass beads, ceramic beads) and indicates physical properties are specified (material, nominal diameter, shape, hardness).
• Machines and projection methods: Two main machine categories - centrifugal (high throughput, wider area) and air-blasting (focused, higher intensity).
• Measurement and control: Procedures for Almen arc height measurement, evaluating coverage, determining saturation time and peening intensity, and measuring residual stress (including X‑ray stress measurement).
• Protection and treatments: Requirements for protecting non‑peened surfaces, plus pre‑peening (cleaning/degreasing) and post‑peening (rust protection, coatings, wrapping) treatments.
• Reporting: Specifies the information to include in process reports to ensure traceability and communication between supplier and purchaser.

Practical applications and users

ISO 26910-1:2023 is directly applicable to:

• Spring manufacturers and designers seeking consistent fatigue and SCC performance
• Shot peening process providers and contract peening shops
• Peening machine and media suppliers
• Quality engineers, metallurgists and test labs performing Almen and residual stress measurements

Use cases include automotive leaf and coil springs, industrial suspension springs, and any mechanical spring components where controlled residual stress and fatigue life are critical.

Related standards

• ISO 80000-1 (Quantities and units) is cited as a normative reference for units and quantities.
• ISO 26910 series - Part 1 is the general procedures document and is part of a broader series on springs and peening practices.

Keywords: ISO 26910-1:2023, shot peening, springs, Almen strip, peening intensity, saturation time, coverage, residual stress, shot peening machine, peening media.