1.Why is spectral detection considered accurate?
Reliable Principle: The physical basis of spectroscopic analysis (commonly such as spark direct-reading spectroscopy and handheld X-ray fluorescence spectroscopy) is atomic energy level transitions. Each element has its unique characteristic spectral lines, like a "fingerprint." By measuring the intensity of these spectral lines, the elemental content can be accurately calculated. This is a mature, physics-based detection method.
Fast and Non-Destructive: The content of all major elements (C, Si, Mn, P, S, Cr, Ni, etc.) can be obtained in a few seconds to one or two minutes without damaging the material.
Suitable for Incoming Material Inspection: It is the most effective means of verifying whether steel grades (such as SPCC, DC01, 08Al, etc.) meet standards and preventing mixing of materials.
2.What role does it play in identifying materials and classifying grades?
This is the core advantage of spectral detection. It can clearly distinguish between ordinary low-carbon steel (such as SPCC), aluminum-killed steel (DC04), high-strength steel (such as Q345), and stainless steel (such as 304). The spectrometer can easily identify the differences in elemental content between different grades with extremely high accuracy. For incoming material verification and prevention of mixing, its accuracy fully meets industrial requirements.
3.What impact does this have on absolutely precise quantitative analysis?
Accuracy Level: Modern spectrometers are highly accurate, but have an error range (e.g., carbon (C) content may have an error of ±0.01%-0.02%). This is more than sufficient for determining material and grade.
Reliance on Standards and Calibration: The accuracy of the instrument is extremely dependent on calibration using standard samples that are matched to the material being tested. An instrument calibrated with a stainless steel standard will produce inaccurate results when measuring ordinary steel. Therefore, standardized laboratory procedures are crucial for ensuring accuracy.
Arbitration Role: In cases of significant dispute over spectral results (such as returns or claims), the results of more traditional, destructive chemical analysis methods (such as carbon-sulfur analyzers and inductively coupled plasma optical emission spectrometry (ICP-OES)) are usually used as the final arbitration basis. Laboratory spectroscopy itself is also frequently used as an arbitration tool.
4.What are the influencing factors in on-site testing?
Surface condition: This is the primary factor affecting the accuracy of on-site testing of cold-rolled coils! Rust-preventive oil, oil film, dust, oxide layer, and passivation film on the surface of cold-rolled coils can severely interfere with the results.
* Best practice: Before testing, the metal surface at the test point must be sanded to a bright, clean, and flat finish using sandpaper or an angle grinder.
* Matrix effect and inhomogeneity: The microstructure and segregation of the steel can affect local measurement values. Multiple measurements at different locations are usually required, and the average value taken.
* Instrument condition and operation: Handheld XRF spectrometers have lower accuracy for detecting light elements (such as C, P, and S) than laboratory spark direct-reading spectrometers. Operators must be trained to ensure tight, perpendicular coupling between the probe and the sample surface.
5.What are the specific recommended procedures for cold-rolled coils?
Surface Pretreatment: Thoroughly remove oil and coatings from the area to be tested (usually near the edge of the roll material), and polish to a bright metallic surface with a diameter of approximately 30mm.
Instrument Selection and Calibration:
Rapid On-Site Screening: Use a handheld XRF spectrometer pre-calibrated with the corresponding steel grade standard.
Precise Laboratory Analysis: Use a spark direct-reading spectrometer, ensuring its calibration curve covers the compositional range of the material being tested.
Multi-Point Measurement: Take 2-3 measurements at different locations on the clean surface and observe the consistency of the data.
Result Comparison: Compare the measured content of major elements with the compositional requirements of the target steel grade according to national/international standards (such as GB, JIS, ASTM, EN) or the procurement technical agreement.
Dispute Resolution: If there is a significant deviation between the spectral test results and the standard, samples should be sent to a third-party authoritative laboratory for arbitration testing using chemical analysis methods.