Forging is a manufacturing process that shapes metal through compressive forces, producing components with exceptional strength and durability. Because forgings are often used in critical applications such as aerospace, automotive, oil and gas, and power generation, ensuring their quality is essential. An effective inspection procedure helps verify that forging products meet design specifications, mechanical property requirements, and industry standards. This article explains the detailed inspection procedure for forging products, covering every stage from raw material selection to final delivery.
Forging inspection ensures that the product performs as intended under its operating conditions. Defects in forged parts can lead to premature failures, operational downtime, or even catastrophic accidents. The inspection procedure:
Confirms dimensional accuracy
Verifies chemical and mechanical properties
Detects surface and internal defects
Ensures compliance with customer and industry standards
In industries like aerospace or nuclear energy, inspection is not just a quality control measure but also a regulatory requirement.
The process starts with verifying the quality of the raw material before forging begins. This includes:
Material Certification Review – Checking mill test certificates for chemical composition and mechanical properties.
Visual Examination – Inspecting billets, ingots, or bars for surface cracks, scaling, or corrosion.
Chemical Analysis – Using spectrographic or X-ray fluorescence (XRF) testing to confirm composition matches specifications.
A reliable supplier like sakysteel ensures that only certified raw materials are used, preventing downstream defects.
Before forging starts, preparatory checks ensure the process can run smoothly:
Dimensional Check of Blanks – Confirming billet size and weight for accurate forming.
Surface Cleaning – Removing rust, scale, or contaminants that could cause forging defects.
Heating Equipment Calibration – Ensuring uniform furnace temperature for consistent metallurgical results.
Monitoring during the forging process is essential for controlling quality:
Temperature Monitoring – Checking forging temperatures to avoid overheating or insufficient deformation.
Process Control Documentation – Recording forging loads, deformation rates, and pass sequences.
Operator Observations – Skilled forgers watch for signs of improper grain flow or cracking during forming.
After forging, the product undergoes a thorough surface examination:
Surface Defect Detection – Identifying laps, seams, or cracks.
Dimensional Measurement – Checking major dimensions with calipers, gauges, or coordinate measuring machines (CMM).
Surface Finish Assessment – Evaluating roughness to ensure it meets the required standard.
Most forgings undergo heat treatment to achieve desired mechanical properties. The inspection here includes:
Furnace Calibration Records – Ensuring heat treatment equipment meets temperature uniformity requirements.
Hardness Testing – Verifying hardness values fall within specification.
Microstructural Analysis – Checking grain size and carbide distribution using metallographic examination.
NDT is a critical stage for detecting internal and surface defects without damaging the forging:
Ultrasonic Testing (UT) – Detects internal voids, cracks, or inclusions.
Magnetic Particle Inspection (MPI) – Finds surface and near-surface cracks in ferromagnetic materials.
Dye Penetrant Inspection (DPI) – Reveals surface-breaking defects in non-ferrous and ferrous metals.
Radiographic Testing (RT) – Provides a visual record of internal discontinuities.
The type of NDT used depends on the forging’s application, size, and material.
Mechanical tests confirm that the forging meets strength, ductility, and toughness requirements:
Tensile Test – Measures yield strength, tensile strength, and elongation.
Impact Test (Charpy V-notch) – Evaluates toughness at different temperatures.
Hardness Test – Determines resistance to indentation.
Testing specimens are taken from representative locations to ensure accuracy.
Precision measurement ensures the forged part fits perfectly in its intended assembly:
CMM Inspection – High-precision 3D measurement for complex geometries.
Gauge Inspection – Using dedicated gauges for repetitive dimensional checks.
Flatness, Roundness, and Straightness Checks – Essential for rotating or sealing components.
After machining or surface treatment (such as grinding, polishing, or coating), final checks are carried out:
Final Visual Examination – Confirming the product is free from damage or defects after finishing.
Coating Thickness Measurement – Ensuring protective layers meet required specifications.
Marking and Identification – Applying traceable identification numbers or barcodes for quality tracking.
A complete set of inspection records accompanies the finished forging. This includes:
Material certificates
NDT reports
Mechanical test results
Dimensional inspection records
Heat treatment reports
Customers receive a final quality dossier to verify compliance with contractual requirements. Manufacturers such as sakysteel maintain these records for traceability and regulatory compliance.
Several industry standards define the inspection requirements for forgings:
ASTM A388 – Ultrasonic examination of steel forgings
ASTM E709 – Magnetic particle examination
ASTM E165 – Liquid penetrant examination
ASME Section VIII – Pressure vessel forging requirements
API 6A – Petroleum and natural gas industry forging standards
Compliance with these standards ensures that forgings meet global market requirements.
Defect Prevention – Early detection of defects avoids costly rework or rejection.
Improved Reliability – Ensures parts perform under extreme operating conditions.
Regulatory Compliance – Meets industry and legal requirements for safety-critical applications.
Customer Confidence – Demonstrates commitment to quality and traceability.
An effective inspection procedure for forging products is essential to ensure quality, safety, and performance. From raw material verification to final documentation, each stage plays a critical role in delivering a defect-free product. Advanced inspection methods, adherence to standards, and thorough quality control ensure that forged components can be trusted in the most demanding environments.
By implementing a robust inspection process, manufacturers can meet customer expectations and maintain a competitive edge in the global market.