Earlier we considered those types of tests that allow us to know the mechanical properties of metals. The metals also have important chemical properties. In fact, it is the chemical composition of the metal and its heat treatment that largely determines its mechanical properties. The part is necessary to determine the chemical composition of the metal. To do this, there are three common methods: spectral analysis, combustion analysis and analysis of the effects of liquid reagents.
The welding inspector rarely has to practice chemical analysis. However, the inspector may need assistance in the sampling and sampling process for analysis or in the process of examining the results of the analysis in order to establish the conformity of the metal to specific technical conditions. More detailed information on the chemical analysis of metals can be found in ASTM’s technical specifications, for example ASTM A751.
The metals analysis can be carried out in the field using the X-ray spectral analysis method. Although this method is characterized by limited possibilities of performing elementary analysis, it helps to avoid confusion in materials and sorting of alloys by type. For those cases when it is necessary to perform only sorting, the special analytical sets are provided, the application of which is based on magnetic properties and qualitative color changes under the action of reagents, which have the very high useful effect. The portable spectrographs are manufactured for more accurate analysis under production conditions.
Another group of tests, which can generally be classified as reagent tests, is designed to test corrosion resistance. These are specific tests, the purpose of which is to determine the corrosion resistance of metals or their combinations. The annual losses from corrosion of metals bring the industry the billion losses. According to one estimate, such annual losses amount to 120 billion dollars. The designers are very concerned about the behavior of metals in a certain aggressive environment. The tests conducted to determine the degree of corrosion resistance are organized in such a way that the real conditions in which the metal will be stored during operation are reproduced as accurately as possible. Among the factors that should be considered when organizing tests for corrosion resistance include chemical composition, corrosive environment, temperature, the presence of moisture, the presence of oxygen, and the presence of other metals and the magnitude of stress. If you do not take into account any of the above factors, the results of corrosion resistance tests may be unreliable.