How to identify 304 stainless steel?

Identifying 304 stainless steel is essential for various applications, from household appliances to industrial uses. Here's a comprehensive guide for you. 304 stainless steel is known for its excellent corrosion resistance and is extensively used in various industries.

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Experimental Analysis

Generally, the components of stainless steel can be thoroughly analyzed through spectroscopy. This method is highly precise and allows for the identification of various elements present in the steel.

Industrial Identification

In the industrial sector, stainless steel can be differentiated by soaking it in chemical solutions. One commonly used solution is stainless steel pickling passivation solution. This method helps in identifying the series but not the specific grade.

SUS300 Series

The SUS300 series, including 304, changes from its natural color to a matte finish when soaked but does not change further.

SUS200 Series

The SUS200 series, such as 201, 202, will immediately turn black upon soaking. The black film can be touched and appears matte. Prolonged soaking will cause visible corrosion and smoking.

SUS400 Series

The SUS400 series, including 410, 420, 430, reacts similarly to the SUS200 series but the black film is not removable by touch. It requires special solutions to remove.

Home Screening Methods

The simplest way to identify 304 stainless steel at home is by using a magnet. SUS304 is non-magnetic and will not be attracted to a magnet. Here are some additional tips:

• SUS200 Series: Slightly magnetic, small objects may be weakly attracted.
• SUS400 Series: Strongly magnetic, similar to iron, strongly attracted to magnets.

For everyday items like a stainless steel thermos cup marked with SUS304, no attraction to a magnet confirms it is 304 stainless steel. If the magnet attracts slightly, it is likely 201, which can leach heavy metals over time and is not recommended for prolonged use. Strong magnetic attraction suggests it is stainless iron, which tends to rust quickly.

Be cautious with products like pots, pans, or cups made from 201 stainless steel, as manufacturers often use cheaper materials to cut costs. Natural color passivation and electrolytic polishing can enhance corrosion resistance but always verify the quality when purchasing.

If you are interested in enhancing the anti-corrosion and anti-rust features of your stainless steel items, feel free to contact me for free solutions.