What Are the Analysis Methods of Forging Quality

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.

1. Visual Inspection

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.

2. Dimensional Inspection

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.

3. Mechanical Properties Testing

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.

4. Chemical Composition Analysis

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.

5. Microstructure Analysis

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.

6. Non-Destructive Testing (NDT)

Purpose:
To detect internal or surface defects without damaging the forging.

Common NDT methods:

a. Ultrasonic Testing (UT)

• Uses high-frequency sound waves to detect internal voids, inclusions, or cracks

• Suitable for thick components like forged blocks or flanges

b. Magnetic Particle Inspection (MPI)

• For ferromagnetic materials only

• Detects surface and near-surface cracks using magnetic fields and iron particles

c. Dye Penetrant Testing (DPT)

• Surface inspection method

• Identifies hairline cracks, porosity, or laps on smooth surfaces

d. Radiographic Testing (RT)

• 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.

7. Residual Stress Testing

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.

8. Hardness Mapping

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.

9. Forging Defect Detection

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.

10. Third-Party and Customer Witness Testing

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.

Conclusion

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.