Stainless steel component identification

Stainless steel is known as INOX in Vietnam.

Stainless means "not rusty".

Strictly speaking, it also includes the meaning of "resistant to rust."

Stainless steel is a rust-resistant alloy whose main component is iron (Fe) (over 50%) and chromium (Cr) over 10.5%, and its usage is rapidly increasing compared to other materials.

The increase in the amount of stainless steel used is thought to be due to the material's excellent properties, which are expanding its uses, and improvements in manufacturing and processing technology.

② Types of stainless steel

The reason why stainless steel is resistant to rust is due to the formation of a chromium-containing oxide film called a "passive film" on its surface.

In addition, even though it is simply referred to as stainless steel, it can exhibit a variety of different characteristics by changing the content ratio of ingredients and processing methods.

For example, austenitic stainless steel used for general piping such as water supply and hot water supply in houses, such as stainless steel fittings made by Benkan Vietnam, not only has excellent corrosion resistance (rust resistance), but also ductility and It is also a material suitable for plastic working due to its high toughness.

Among them, the common SUS304 contains 18% chromium (Cr) and 8% nickel (Ni).

③Importance of identifying types and components

Currently, stainless steel is used in a wide variety of fields and applications, taking advantage of its characteristics such as corrosion resistance, heat resistance, and aesthetics.

However, just because it is made of stainless steel does not mean that it can be used for any purpose. By using the right material in the right place, matching the characteristics of each stainless steel, and using it for the appropriate purpose, you will be able to maximize its capabilities.

For this reason, correct identification of the type and ingredients is required.

However, according to the results of a survey on the labeling of various stainless steel products by the Japan Stainless Steel Association. There have been a number of imported products that not only have misleading labeling, but have also been reported to be incorrectly displayed.

④ Measures to classify and check ingredients

Currently, the stainless steel used in Benkan Vietnam is SUS304 austenite type.

When receiving raw materials, we perform composition testing with a composition analyzer for each batch and compare the results with the ingredients' composition classification table.

In the past, composition testing followed traditional chemical analysis methods, the biggest problem of this method was distinguishing between analytical purposes or separation of target elements and non-target elements.

In fact, pre-treatment of precipitation, filtration, extraction, evaporation, and distillation not only prolongs analysis time but also reduces accuracy due to high skill requirements.

However, the development of mechanical component analysis methods has received great attention in recent years. Current compositional analyzers using emission spectroscopy can conduct non-destructive testing of metals of various elements in approximately 20 seconds from the time the specimen is set up.

▲Sample after composition analysis.

At Benkan Vietnam, we have applied a composition analyzer based on this emission spectroscopy method.

This method is performed by arcing and sparking between electrodes onto the metal surface. Use the properties of light emitted from the electrons of each element.

Then, by examining the characteristic line spectra of the element, the quantitative values ​​of the elements in the metal, oxide symbols, ratios of elements and other parameters can be measured.