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What are the methods for judging the material of stainless steel wire
- 2021-03-09-

Stainless steel wires are all over our lives, such as ballpoint pen springs, cart baskets, chains on popular ladies' bags, protective covers for electric fans, pull-back wires for umbrellas, hangers, barbecue racks, barbecue forks, etc. It is made of stainless steel wire with different specifications, so here we will explain to us the different methods of stainless steel wire raw materials, so that you can better choose the stainless steel wire that suits you.

1. Magnetic test method

The magnetic test method is a more common simple method to distinguish austenitic stainless steel from ferritic stainless steel. Austenitic stainless steel is a non-magnetic steel, but it will have mild magnetic properties after cold working under high pressure; while plain chromium steel and Low alloy steels are all strong magnetic steels.

2. Nitric acid spot test method

A distinctive feature of stainless steel wire is its inherent corrosion resistance to concentrated nitric acid and dilute nitric acid. This performance makes it easy to distinguish it from most other metals or alloys. However, high-carbon 420 and 440 steels are slightly corroded during nitric acid spot test. Non-ferrous metals are corroded immediately when they encounter concentrated nitric acid, while dilute nitric acid is highly corrosive to carbon steel.

3. Copper sulfate spot test method

The copper sulfate spot test is a simple way to quickly distinguish between general carbon steel and all types of stainless steel wires. The concentration of the copper sulfate solution used is 5%-10%. Before the spot test, the test area should be thoroughly cleaned of oil or For other impurities, use a grinder or soft abrasive cloth to polish a small area, and then drop the test liquid to the polished place. Generally, carbon steel or iron will form a layer of surface metal copper within a few seconds, and try the appearance of stainless steel. Then there will be no copper precipitation or the appearance of copper color.

4. Sulfuric acid test method

Sulfuric acid immersion stainless steel can distinguish 302 and 304 from 316 and 317. The cut edge of the sample must be finely ground, and then cleaned and passivated in sulfuric acid with a volume concentration of 20%-30% and a temperature of 60-66°C for half an hour. The volume concentration of the sulfuric acid solution is 10% and heated to 71°C. When 302 and 304 are immersed in the solution, the steel is quickly corroded and many bubbles occur, and the sample turns black within a few minutes; while the 316 and 317 steel samples are not corroded or corroded very slowly (no bubbles). The test does not change color within 10-15 minutes.