Forging is a critical manufacturing process used to produce high-strength, durable components such as shafts, gears, flanges, rods, and rings for industries like aerospace, automotive, energy, and petrochemicals. However, the performance and reliability of forged parts heavily depend on their quality.
Ensuring the quality of forgings is not just about surface appearance; it involves detailed analysis of internal and external properties through various testing and inspection methods. By applying these techniques, manufacturers can detect defects early, reduce failure risks, and meet international standards.
In this article, we explore the main analysis methods of forging quality, covering dimensional, mechanical, metallurgical, and non-destructive testing techniques. These quality control processes are essential for achieving defect-free, high-performance forged components.
Purpose:
To identify visible surface defects or abnormalities immediately after forging and during post-processing.
What it detects:
Surface cracks
Laps and folds
Burrs and flash
Surface roughness
Scaling and discoloration
Tools used:
Naked eye under proper lighting
Hand-held magnifiers
Digital cameras for documentation
Advantages:
Quick and cost-effective
Can be performed in-line during production
Helps determine if more detailed inspection is needed
At sakysteel, visual inspection is part of the standard operating procedure after forging and machining.
Purpose:
To ensure that the forged part meets specified tolerances for size, geometry, and alignment according to engineering drawings and standards such as ASME, ASTM, or EN.
What it measures:
Outside and inside diameters
Thickness and length
Flatness and straightness
Bore alignment
Bolt hole positions (for flanges)
Tools used:
Vernier calipers and micrometers
Coordinate Measuring Machine (CMM)
Height gauges and dial indicators
Go/no-go gauges
Importance:
Dimensional accuracy affects part compatibility, sealing performance, and mechanical behavior. Deviations may lead to misfits or assembly failures.
Purpose:
To verify that the forged material meets the mechanical performance requirements specified in standards or customer contracts.
Common mechanical tests:
Tensile test: Measures yield strength, tensile strength, and elongation
Hardness test: Determines material resistance to indentation (Brinell, Rockwell, or Vickers)
Impact test (Charpy): Evaluates toughness at different temperatures
Bend test: Confirms ductility
Equipment used:
Universal testing machines
Hardness testers
Impact testers
These tests are especially important for pressure-bearing components such as valves, flanges, and pipe fittings. sakysteel provides full mechanical test certificates (MTC) for each batch.
Purpose:
To confirm the chemical makeup of the forged material, ensuring consistency with material standards like ASTM A105, A182, or DIN 1.4541.
Methods used:
Optical Emission Spectroscopy (OES)
X-ray Fluorescence (XRF)
Wet chemical analysis (for precise laboratory testing)
Why it matters:
Chemical composition directly affects corrosion resistance, heat resistance, weldability, and mechanical strength.
Company sakysteel uses certified spectrometers to test raw materials and verify product compliance before dispatch.
Purpose:
To examine the internal grain structure and identify any undesirable phases or inclusions that could weaken the part.
What it reveals:
Grain size and orientation
Carbide or oxide formation
Non-metallic inclusions
Phase distribution (austenite, ferrite, martensite)
Effects of heat treatment
Methods used:
Optical microscopy
Scanning electron microscopy (SEM)
Etching and polishing procedures
Benefits:
Understanding microstructure helps validate heat treatment effectiveness and predict long-term performance in demanding environments.
Purpose:
To detect internal or surface defects without damaging the forging.
Common NDT methods:
Uses high-frequency sound waves to detect internal voids, inclusions, or cracks
Suitable for thick components like forged blocks or flanges
For ferromagnetic materials only
Detects surface and near-surface cracks using magnetic fields and iron particles
Surface inspection method
Identifies hairline cracks, porosity, or laps on smooth surfaces
Uses X-rays or gamma rays to detect internal flaws
Mostly used for high-integrity components in nuclear or aerospace applications
Advantages of NDT:
Maintains part integrity
Ensures safety and compliance without part destruction
Widely accepted by third-party inspectors and certification bodies
At sakysteel, NDT is conducted according to ASME and ISO standards, with certified operators and detailed inspection reports.
Purpose:
To identify and control internal stresses that may remain after forging and heat treatment.
Why it’s important:
Residual stress can cause:
Warping during machining
Cracking during service
Reduced fatigue resistance
Methods used:
X-ray diffraction
Hole-drilling method
Stress-relief heat treatment (if required)
Managing residual stress is vital for precision components used in rotating machinery and pressure vessels.
Purpose:
To ensure uniform hardness distribution across the part, especially after heat treatment.
Technique:
Multiple hardness tests at different locations
Mapping results to ensure consistency
Applications:
Commonly used for large flanges, rings, shafts, and forged blocks.
Inconsistent hardness may indicate problems such as improper cooling, microstructure abnormalities, or material segregation.
Common forging defects include:
Cracks
Folds and laps
Underfilling
Inclusions
Segregation
Shrinkage cavities
Detection methods:
NDT (UT, MPI, DPT)
Microstructure analysis
Macroscopic examination of sample cuts
Early detection helps avoid rework or product rejection at the customer’s end.
For critical components or project-based orders, third-party inspection agencies or customer representatives may witness quality tests.
Common certifications involved:
EN 10204 3.1 or 3.2
ISO 9001
API, PED, NORSOK
SGS, TUV, BV inspection reports
At sakysteel, customer-specific quality control plans (QCP) are developed to ensure full transparency and compliance with project documentation.
Forging quality cannot be guaranteed by appearance alone. A combination of dimensional checks, mechanical tests, metallurgical analysis, and non-destructive evaluations is essential to ensure the integrity and reliability of forged components.
By using advanced testing and inspection methods, manufacturers can:
Detect and eliminate defects
Comply with international standards
Deliver products with consistent performance
Build long-term customer trust
sakysteel integrates these quality control methods across every stage of production, from material sourcing to final inspection. With professional facilities and a commitment to excellence, we provide customers with forged products they can trust in the most demanding applications.