Stainless steel is one of the most popular types of metal products. Pipes, sheet metal, hexagons, and circles - all stainless steel product options are in high demand in the modern economy. But alas! - it is a high demand that creates a situation in which not too conscientious manufacturers begin to trick, reduce the cost of production - and ultimately supply consumers with products whose quality, to put it mildly, does not match the declared. Accordingly, the question of how to check the quality of carbon steel pipe is also becoming relevant.
Accordingly, the consumer can check the parameters indicated in the documents: the diameters and wall thickness of the alloy steel pipe are checked, the shape of the squares and hexagons of the stainless steel are accurate, the deflection and the wave of the rolled stainless sheet are checked.
There remains the need to verify the chemical composition of stainless steel tubes since most production flaws will be associated with a violation of such a composition.
Method of Archimedes
It is because the density of stainless steel is quite strongly related to its composition - a metal with a high nickel content will be slightly less dense than just carbon steel. Therefore, if the alloying additions in the a106 grade b stainless steel are less than necessary, then this will affect the specific gravity of the metal product.
Copper sulfate on guard of quality
The second rather simple way is to check the chemical composition of astm a53 stainless steel using copper sulfate CuSO4 (also known as copper sulfate).
If you attach cotton wool or a cloth dampened with a 20% copper sulfate solution to a sand-peeled surface of a stainless steel product, then in a day, you can judge the quality of the stainless steel by the color of its surface.
Iron, being a more chemically active metal, will displace copper from its compounds strictly according to the formula known to us from the school course of inorganic chemistry:
Fe + CuSO4 = FeSO4 + Cu
Correspondingly, the iron displaced by the copper will fall onto the surface of the steel production in the form of a dark-red coating visible with the naked eye.
How to test stainless steel for corrosion?
It must be remembered that the corrosion resistance of a333 grade 6 stainless steel is, in principle, not absolute - and stainless steel, depending on the conditions, will nevertheless be exposed. The only question is - how fast? According to this indicator, high-quality stainless steel will also differ from that which is not very.
The susceptibility of stainless steel to surface (linear) corrosion is assessed by placing the sample in an airtight container with high (not less than 70-75%) humidity and temperature (from 30 to 300 ° C).
At the same time, during 10-hour tests, a corrosive medium (acid solutions or copper sulfate) is periodically added to the tank. After a 10 or 15 hour respite, the test is repeated.
The part is subjected to boiling in an aqueous solution that contains 10% sulfuric acid and 10% copper sulfate during the day to assess the resistance of stainless steel to intergranular corrosion,
Such tests can be carried out in any workshop where suitable tanks can be built - and then compare the results obtained with those for the given varieties of api 5l grade b stainless steel.