Wrought Aluminum Testing

Wrought aluminium inspection mainly conducts scientific testing and analysis on the chemical composition analysis, mechanical property testing, metallographic structure analysis, dimension and shape deviation inspection, surface quality inspection and macrostructure examination, objectively assessing the product quality grade and issuing a detailed test report, providing a basis for manufacturers' quality control and downstream users' product acceptance.

Testing Items

Chemical composition analysis: The contents of the main elements (such as the Si, Fe, Cu, Mn, Mg, Cr, Zn and Ti) and the impurity elements in the wrought aluminium alloy are precisely determined through the methods such as the spectroscopy and mass spectrometry, ensuring that they meet the requirements of the alloy designations. This is the key for judging the basic performance and processability of the material.

Mechanical property testing: Mainly including the tensile testing and hardness testing. The tensile testing determines the tensile strength, yield strength and elongation after fracture of the material; the hardness testing (Brinell, Rockwell and Vickers) evaluates the ability of the material to resist the local plastic deformation, directly reflecting its load-bearing and wear resistance performances.

Metallographic structure analysis: An optical microscope or scanning electron microscope is used to observe the microstructure of the material, such as the grain size, morphology, second-phase distribution, inclusion types and quantities, and whether there are the defects such as the overburning and coarse grains, thereby evaluating the heat treatment state and intrinsic quality of the material.

Dimension and shape deviation inspection: The tools such as the callipers, micrometers, laser diameter measuring instruments and profilometers are used to precisely measure the sheet thickness, profile cross-section dimensions, inner and outer diameters and wall thicknesses of the tubes, and bar diameters, and check whether their straightness, flatness and twist meet the requirements of the product standards.

Surface quality inspection: Through the visual inspection or low-power magnifying inspection, it is checked whether there are the defects such as the cracks, peeling, bubbles, corrosion spots, scratches, indentations and orange peel on the product surface. For the products with the high requirements, the coating performance tests such as the anodic oxide film thickness and sealing quality also need to be carried out.

Macrostructure examination: Through the macro-etching, the macroscopic defects such as the flow lines, shrinkage cavities, porosity, inclusions and delaminations of the material are observed at the low magnification. It is commonly used to evaluate the ingot quality and the rationality of the subsequent processing process, and is an important means for predicting the performance consistency of the material.

Physical property testing: Including the determination of the density, electrical conductivity, thermal conductivity and thermal expansion coefficient. These performances are crucial for the application of the material in the specific fields such as the electronics, heat dissipation and aerospace, and are the important basis for the material selection and design.

Testing Scope

Wrought aluminium alloy plates and sheets: Widely used in the fields such as the aerospace, transportation and building decoration. The testing focuses on the mechanical properties, formability, corrosion resistance and surface quality, ensuring that they meet the requirements of the design and use.

Wrought aluminium alloy bars and rods: Used in the mechanical parts, fasteners and structural components. The testing emphasizes the tensile strength, yield strength, hardness and dimensional accuracy, ensuring the reliability of the machined parts.

Wrought aluminium alloy tubes and pipes: Applied in the heat exchange, fluid transportation and structural supports. The testing needs to focus on the wall thickness uniformity, pressure resistance, weldability and corrosion resistance.

Wrought aluminium alloy profiles: Such as the building profiles, automotive profiles and rail transit profiles. The testing focuses on the cross-section dimensional accuracy, surface treatment quality (anodizing and powder coating), and the mechanical properties in the different directions.

Wrought aluminium alloy forgings: Used for the structural parts of the aircraft, automotive and machinery. The testing needs to emphasize the macrostructure examination (such as the flow lines and shrinkage cavities), mechanical properties and the ultrasonic flaw detection, ensuring the internal quality of the forgings.

Raw materials and semi-finished products: Including the ingots, billets and the products at the various stages of the processing. The testing at the different stages ensures the process quality control from the source and throughout the whole process.

Testing Methods

Chemical analysis method: The spark direct-reading optical emission spectrometer (OES) is used for the rapid multi-element determination; the inductively coupled plasma optical emission spectrometer (ICP-OES) or inductively coupled plasma mass spectrometer (ICP-MS) is used for the precise determination of the trace elements and impurities. The results are compared with the alloy designation requirements in GB/T 3190 for the judgement.

Mechanical testing method: The tensile testing is carried out according to the standards such as GB/T 228.1 and ISO 6892-1, and the specimens are stretched at the specified rate on a universal testing machine. The hardness testing is carried out according to the standards such as GB/T 231.1, GB/T 230.1 and GB/T 4340.1, using the corresponding hardness testers and scales.

Metallographic analysis method: The specimens are prepared by the cutting, mounting, grinding, polishing and etching, and then observed under an optical microscope or scanning electron microscope. The grain size is rated according to the standards such as GB/T 6394; the overburning and coarse grain defects are judged by comparing the microstructure characteristics.

Dimension measurement method: The routine dimensions are measured with the callipers and micrometers; the high-precision and complex dimensions are measured with the coordinate measuring machines (CMM); and the laser scanners are used for the rapid full-surface measurement and comparison with the CAD models.

Surface quality inspection method: The visual inspection is carried out under the sufficient lighting conditions, and the low-power magnifying inspection is carried out when necessary. For the surface coating quality, the eddy current thickness gauges are used to measure the anodic oxide film thickness, and the dye penetration testing is used to evaluate the sealing quality.

Non-destructive testing method: The ultrasonic flaw detection is used to detect the internal defects such as the cracks and inclusions; the eddy current flaw detection is sensitive to the surface and near-surface defects; and the radiographic testing is used for the detection of the important parts or the verification of the suspected defects.

Testing Standards

Domestic Standards:

1. GB/T 3190, Wrought aluminium and aluminium alloys — Chemical composition

2. GB/T 228.1-2021, Metallic materials — Tensile testing — Part 1: Method of test at room temperature

3. GB/T 229-2020, Metallic materials — Charpy pendulum impact test method

4. GB/T 232-2010, Metallic materials — Bend test method

5. GB/T 230.1-2018, Metallic materials — Rockwell hardness test — Part 1: Test method

6. GB/T 4340.1-2009, Metallic materials — Vickers hardness test — Part 1: Test method

International Standards:

1. ISO 6892-1, Metallic materials — Tensile testing — Part 1: Method of test at room temperature

2. ISO 9227, Corrosion tests in artificial atmospheres — Salt spray tests

Note: The applicable standard can be selected according to the product use and customer trade requirements; standards agreed in the contract take precedence over general standards.

Testing Instruments and Equipment

Inductively coupled plasma optical emission spectrometer: As the core equipment of the chemical composition analysis, it is composed of a sample introduction system, ICP light source, spectroscopic system and detection system. The high-resolution spectrometer can effectively avoid the spectral interference, ensuring the accuracy of the analysis of the various elements in the complex aluminium alloy matrix.

Electronic universal material testing machine: Equipped with the high-precision load cells and extensometers, used for the mechanical property tests such as the tensile, compression and bending. The modern testing machines integrate the digital control systems and data acquisition software, realizing the automatic control of the testing process and the result calculation.

Metallographic specimen preparation system and microscope: The system includes the automatic cutting machines, mounting machines, grinding and polishing machines and etching devices. The research-grade upright or inverted metallographic microscopes are equipped with the multiple observation modes such as the bright field, dark field, polarization and differential interference, and are connected to the image analysis software for the quantitative metallographic analysis.

Ultrasonic flaw detector and probes: The instrument emits and receives the high-frequency electrical pulses, which are converted into the ultrasonic waves through the piezoelectric probes. According to the different inspection objects, the straight-beam probes, angle probes, twin-crystal probes or immersion focusing probes need to be selected, and the automated inspection can be realized with the mechanical scanning devices.

Portable spectrometer and eddy current instrument: The portable spark/arc direct-reading optical emission spectrometer is suitable for the on-site material designation identification and rapid composition analysis; the portable eddy current flaw detector is light and flexible, and is commonly used for the rapid screening and positioning of the surface defects of the aluminium materials on the in-service equipment or construction sites.

Precision dimension measuring equipment: The coordinate measuring machines measure the spatial point coordinates through the probe contact; the laser scanners rapidly obtain the massive point cloud data of the object surface in a non-contact manner; and the optical projectors and image measuring instruments are suitable for the efficient comparison measurement of the two-dimensional profiles and plane dimensions.