In precision welding processes such as laser welding, arc welding, resistance spot welding, and friction stir welding, penetration is the core gold standard for determining welding strength, tightness, and service life.
Many products have a perfect welding appearance, but fail in tensile, vibration, and pressure resistance tests. The core reasons are: insufficient internal penetration, poor fusion, hidden pores, and impervious defects.
Welding penetration microscope metallographic inspection is currently recognized as the most accurate, most versatile and authoritative non-destructive/lossy metallographic inspection program in the industry. It is widely used in new energy vehicles, power batteries, rail transit, pressure vessels, aviation precision hardware and other fields.
Today, we will comb through the standardized process from sampling to reporting, and understand the complete logic of regular weld penetration detection!
01 Why is penetration microscopy necessary?
The welding appearance can only see the surface molding, and it is impossible to judge the true welding quality inside:
• Flawless surface ≠ No pores inside, slagging, cracking, not fused
• Manual visual inspection cannot quantify penetration, heat-affected zone, weld foot size
Through cross-sectional metallographic analysis, weld penetration microscopy visually presents the internal structure of the weld, accurately quantifies the core parameters, and is an indispensable testing means for product quality inspection, process rectification, incoming material audit, and third-party inspection.
Core detection parameters: effective penetration, root penetration, melting width, weld height, weld height, heat affected zone width, internal defect inspection
02 Industry standard 9-step inspection whole process (full version)
There is no shortcut for normal penetration detection, and the measurement accuracy is directly determined at each step. The standardized operations throughout the whole process are as follows:
Avoid unstable areas such as arcing and closing of the weld, select the effective forming section of the weld, and use the vertical weld section of the metallographic cutting machine to cut and sample. Ensure that the cut surface is flat, free of squeezing and burns, avoid damaging the original structure of the weld, and lay the foundation for subsequent inspection.
Step 2: Cold/hot inlay fixed ZXQ-2 (with water cooling)
For small, special-shaped, thin-walled solder joint specimens, the specimen is fixed by cold inlay or hot inlay process. On the one hand, the specimen shape is regularized, which is convenient for grinding and polishing; on the other hand, it protects the weld edge from falling off and chipping, eliminates detection errors, and is suitable for all kinds of precision solder joints and tiny weld detection.
Step 3: Rough grinding and leveling YMP-2B or automatic grinding and polishing machine YMPZ-1
Use coarse sandpaper to roughly grind the cutting section, remove the residual cut marks, oxide layer, and burrs, and grind the height drop, so that the overall weld section is smooth and uniform, and the surface defects of subsequent fine grinding and polishing are eliminated.
Gradually replace fine-grained sandpaper with fine-grained sandpaper, gradually eliminate rough grinding scratches, and refine the cross-sectional flatness, so that the transition area between the weld and the base metal is clear and flat, laying the groundwork for mirror polishing, and ensuring that subsequent microscopic imaging is free of impurities.
Polished with diamond polishing agent and abrasive polisher, the specimen cross-section is polished to the mirror without scratches. At this time, the naked eye observation section is bright and flat, without any abrasion marks or numb spots, which is the key prerequisite for subsequent chemical corrosion and clear imaging.
According to the material of the base material, the special corrosion solution is matched: nitric acid alcohol solution is used for carbon steel, mixed acid solution is used for stainless steel, and special Keller reagent is used for aluminum alloy. Through precise corrosion, the weld melting zone, fusion line, heat-affected zone, and base metal form a clear color difference demarcation, and the original invisible weld structure is fully displayed.
Step 7: ST155R Weld Depth Microscopy Observation
Place the prepared qualified specimen on the ST155R welding penetration microscope stage, adjust the up and down led ring light sources, and focus and zoom. The equipment can achieve 7-45 times continuous zooming, adapt to all kinds of specimens over a long working distance, clearly capture the entire cross-section of the weld, and have no defects such as tiny pores, micro-cracks, and unfused defects.
After the measurement is completed, the system can batch statistics the test data, automatically organize the graphic and text data, and export the Word/PDF standardized test report with one click. The report contains sample information, equipment parameters, measured data, morphology pictures, and qualification results, and can be directly used for workshop quality inspection, customer review, process archiving, and third-party acceptance.
Compared with traditional manual caliper measurement and ultrasonic coarse measurement, the advantages of the entire microscope inspection system are outstanding:
• Higher accuracy: micron-level measurement, eliminating manual reading errors, accurate data traceability
• Intuitive imaging: visualization of the internal structure of the weld, defects at a glance
• Wide adaptability: compatible with all processes such as laser welding, MIG/TIG arc welding, spot welding, friction welding, etc.
• Universal materials: carbon steel, stainless steel, aluminum, copper, titanium and all other metal welding specimens can be detected
• Reporting specifications: standardized graphic and text reports to meet the needs of enterprise quality inspection, customer inspection, and industry certification
Through the entire inspection process, various welding quality problems can be accurately determined:
• Insufficient penetration and lack of penetration (substandard welding strength, easy to break)
• Weld pores, slagging, cracks (sealability, stability failure)
• Uneven melting width and large heat-affected zone (abnormal welding process parameters)
• Asymmetric welding feet, excessive surplus height (appearance and structure are not up to standard)
The core of welding quality is inside, not on the surface. Standardized penetration metallography testing is a key means to control the welding process, eliminate batch defects, and improve product reliability.
A complete welding penetration microscope system empowers the entire process from sample preparation to data reporting, upgrading welding quality inspection from "empirical judgment" to data, visualization, and standardized accurate testing, helping enterprises strictly control welding quality and optimize production processes!
If you need equipment parameters, actual shooting renderings, test cases, and quotation plans, you can consult and obtain them at any time!
Tell us the material, the feature you need to see and the magnification range. We will recommend a configuration and quote it.
