ISO 4992-2:2020

Overview

ISO 4992-2:2020 - Steel castings - Ultrasonic testing - Part 2: Steel castings for highly stressed components specifies ultrasonic testing (UT) requirements for ferritic steel castings intended for highly stressed components. It covers the pulse‑echo technique for detecting and sizing internal discontinuities, typical pre‑treatments (e.g., grain‑refining heat treatment), test scope up to 600 mm wall thickness (greater thicknesses require special agreement), and explicitly excludes austenitic steels and joint welds. Purchasers determine whether a component is “highly stressed” based on performance or safety needs.

Key technical topics and requirements

• Scope and applicability: Ferritic steel castings for highly stressed applications; wall thicknesses ≤600 mm; special arrangements for >600 mm.
• Testing method: Pulse‑echo ultrasonic testing with specified probe, frequency and instrument considerations.
• Zones and sizing rules: Division into rim zone (one‑third of through‑wall thickness, max 30 mm) and core zone for acceptance evaluation; rules for planar and volumetric discontinuities and distance criteria between indications.
• Acceptance criteria: Purchaser-specified acceptance levels and classes; notable limits include that indications exceeding 3 mm FBH are unacceptable for class 1, and through‑wall dimensions are limited (generally ≤10% of wall thickness, with specific exceptions such as small lengths ≤10 mm).
• Non‑measurable discontinuities: Guidance for when discontinuity dimensions cannot be measured (industry practice: <3 mm taken as non‑measurable) and area calculation conventions (e.g., A = 3 × L when through‑wall width assumed 3 mm).
• Equipment and setup: Requirements for instruments, probes/transducer frequencies, coupling fluids, sensitivity and resolution checks, and calibration (references to calibration blocks).
• Procedure, reporting and personnel: Surface preparation, range/sensitivity setting, recording limits, characterization and sizing procedures, and qualification of NDT personnel.

Practical applications and who uses this standard

ISO 4992-2:2020 is used by:

• NDT engineers and inspectors performing ultrasonic testing on critical cast parts
• Castings manufacturers and quality managers specifying acceptance criteria for highly stressed components (e.g., pressure-containing parts, rotating machinery, safety-critical structures)
• Purchasers and design engineers who define test scope and acceptance levels for safety/performance
• Certification bodies and laboratories establishing UT procedures and training programs

Practical benefits include consistent defect detection and sizing, repeatable acceptance decisions, and improved safety and reliability of highly stressed steel castings.

Related standards (normative references)

Key referenced ISO standards include:

• ISO 2400, ISO 7963 (calibration blocks)
• ISO 5577 (UT vocabulary)
• ISO 9712 (NDT personnel qualification)
• ISO 16810 / ISO 16811 / ISO 16827 (UT principles, sensitivity, characterization)
• ISO 22232 series (equipment verification)

Keywords: ISO 4992-2:2020, ultrasonic testing, steel castings, pulse-echo, ferritic, highly stressed components, NDT, acceptance levels, rim zone, FBH.