The core of weld penetration detection is not "take a weld photo", but through standardized sampling, cross-section sampling, calibration and measurement, it can stably obtain data such as penetration, melting width, and heat-affected zone width. If you only zoom in one magnification, or manually estimate the size after taking a screenshot, there will often be problems that the results cannot be reproduced and the data of different detectors are inconsistent.
The sampling position should be representative of the actual welding quality. For long welds, only the section with the best appearance can be taken; for failure parts, cracks, impermeability, pores or suspected areas of insufficient penetration should be preferentially included. Record the workpiece number, welding process, sampling direction and cross-sectional position.
Overheating and mechanical deformation should be avoided during cutting. The cutting direction is as perpendicular to the weld as possible, and the cooling is sufficient to prevent the fusion line and the heat-affected zone from being damaged. Sheets, battery lugs, and small parts require the use of suitable fixtures and protective materials.
Weld seam cross-sections usually need to be inlaid to protect the edges and then polished step by step. The corrosion mode and time shall be confirmed according to the base metal, welding materials and testing standards. The fusion line is unclear when corrosion is insufficient, and excessive corrosion may mask small cracks and pores.
The sample preparation process can refer to the entire process of optical metallographic sample preparation, but the actual parameters should be adjusted in combination with materials and corporate standards.
The weld cross-section should not only look at the overall topography, but also measure the local dimensions. Stereomicroscopy is suitable for low magnification overall inspection, and metallographic microscopy is suitable for high magnification observation of fusion lines, heat-affected zones, and tissues. Uneven or multi-layered structures may require a combination of brightfield, darkfield, or oblique lighting.
The ST155R weld penetration detection microscope can be used with industrial cameras and measurement software for weld, penetration, melting width and heat affected area observation. Product page: ST155R Weld Depth Detection Microscope.
ST155R Weld Depth Detection Microscope for use with cameras and measuring software
JM435 Upright metallographic microscope can be used when higher magnification is required to observe the fusion line and tissue
The current objective, camera and software should be calibrated using a ruler or standard before measurement. After changing the objective, camera position, working distance or software settings, the validity of the calibration should be reconfirmed. Pixel sizes that are not calibrated cannot be directly used as millimeter or micron results.
Maintain the base metal surface datum line, weld boundary and measurement annotation during measurement. It is recommended to save the original diagram, the annotation diagram, the magnification, the calibration information and the inspector at the same time. When multiple sections are involved, the location and results should be recorded separately, not just one final screenshot.
The report may include sample number, material and welding method, cross-sectional position, sample preparation method, microscope and camera configuration, magnification, measurement items, results, images, and basis for determination. If the customer has a specified standard, it shall be carried out in accordance with the parts and statistical methods specified in the standard.
The same batch of samples is recommended to fix the sampling direction, sample preparation process, corrosion conditions, objective magnification, lighting method and surveyor training requirements. After replacing the sandpaper, corrosion time or camera position, it should be confirmed whether the boundary has changed significantly.
The heat input of laser welding and electron beam welding is concentrated, the melting width may be narrow, and excessive cutting and corrosion should be avoided to change the boundary; the weld size of arc welding and submerged arc welding is large, and it is necessary to take into account the center of the weld, the fusion line and the heat affected zone; resistance spot welding usually requires sampling through the center of the solder joint and recording the size of the nucleus; friction stir welding should pay attention to the shape of the nucleus zone and the heat affected zone.
The sampling quantity, cross-sectional direction and determination position shall be specified by the product drawings, process documents or customer standards. Measuring only one position represents the entire weld, which is often insufficient to account for quality fluctuations.
The cross-sectional method requires sampling and cutting, but the fusion line and internal defects can be directly observed. Non-destructive methods are suitable for screening or special scenarios, but they cannot simply replace all cross-sectional measurement requirements, and should be selected according to product standards.
Stereoscopic microscopy is suitable for low magnification overall topography and operational positioning, and metallographic microscopy is suitable for high magnification observation of tissue and fusion lines. Many inspection scenarios will be used in combination, or select configurations that can override the desired magnification and measurement functions.
Direct measurements with unlabeled phone photos are not recommended. For formal dimensional measurements, calibrated microscope cameras and measuring software should be used for reference purposes only.
Please provide the welding method, base metal and welding material, thickness, sample size, items to be measured and report format. Instrument Card Ink Optics can assist in configuring microscopes, cameras, light sources and measurement software, and confirm the overall program with the sample preparation process.
Submit weld sample information for penetration testing configuration recommendations
Tell us the material, the feature you need to see and the magnification range. We will recommend a configuration and quote it.
