High-quality and special steel from LSW meets the highest quality standards of the sector. That's why we thoroughly test our products after production prior to confectioning. In addition to repeated anti-mixing testing with Magnatest and spectral analysis, we also conduct crack testing of the bar surface and ultrasonic testing of the core.
Several quality assurance processes are also available in our laboratories. These are divided into such test areas as raw material analysis, spectral laboratory, mechanical technological test laboratory and metallography.
In raw material analysis we proof the analytical composition of our steel, assessing alloying and trace elements. By means of a pneumatic delivery system, steel samples are delivered to our spectral laboratory for checking directly from the various stages of smelting and metallurgical treatment. In an automatic grinding and fixing unit the samples are prepared for the radioactivity test and the spectrometric analysis. The chemical composition of the steel samples is assessed by means of a spark emission spectrometer while gas chromatography is employed to determine the content of carbon, sulphur, oxygen, nitrogen and hydrogen.
Slag samples are also taken and prepared for X-ray fluorescence analysis checking.
In our mechanical laboratory another typology of tests is carried out on our broad range of high-quality steel products and rebars. Here hardness and tensile strength are controlled. Steel samples undergo suitable heat treatments and forging procedures during which our customers’ complex transformation and machining processes are simulated as closely as possible.
Specific inspections required for high-quality and engineering steel include, for example, the following:
- Tensile test with micro-train measurement
- Notched bar impact bend test and dynamic breaking load test (Brugger test)
- Hardness measurement according to Brinell, Vickers and Rockwell
- Determination of the Jominy hardenability
- Simulation of technical heat-treatments such as normalising, case hardening, quench & tempering and isothermal transformations
For rebars testing an automatic testing unit is available in our fully automated testing centre. This unit is able to determine the meter weight, to measure the ribs and to assess the tensile strength – including the automatic saw cut.
In our metallurgical laboratory the internal structure of our steel and its degree of purity are inspected. The standards, methods and tolerances to be applied are discussed and agreed upon in advance with our customers. In our metallographic department the most modern testing equipment is available.
The preparation of the cross-section specimens to make visible the structure of the steel samples can take place either manually or fully automatically in case of larger quantities.
For optical microscopic inspections we have stereo and incidental light microscopes available. For example, the microscopic purity degree can be determined according to DIN 50602 or ASTM E 45, while the primary and secondary corn sizes are usually determined according to DIN EN ISO 643.
Additionally, other micro and macro etching methods may be employed to expose the internal structure of raw steel. Sulphur prints (Baumann) to examine the structure of steel at casting stage are also commonly employed.
With a scanning electron microscope (SEM) we have the possibility to detect and assess the morphological nature and the chemical consistence of non-metallic inclusions. We also use the SEM for targeted particle analysis.
The macro degree of purity for steel bars is determined by LSW specialists with the ultrasound immersion technique method according to SEP 1927. Ultrasound testing, and in particular that for the determination macro cleanliness, has to be undertaken by trained and certified personnel according to DIN EN 9712 and the SNT-TC-1A guideline of ASNT.
Macroscopic surface controls of steel bars by means of a magnetic particle test help reveal surface discontinuities. These can also be carried out at microscopic level for completeness of inspection.