Stainless steel has remained a sought-after material for many decades. It is used in different industries: household, medical, heavy industry. The question how much can you get for scrapping your car also remains popular.
Given the popularity of this metal, people often look for affordable methods of determining stainless steel at home. In this article, we will talk about them.
Features and characteristics
Before answering the question, it is advisable to understand why this metal is so popular. It’s all about its properties and features:
Resistance to the environment, including aggressive.
Good resistance to wear and tear. With active use, products last more than a dozen years.
No reaction to rapid changes in ambient temperature.
Lack of predisposition to the appearance and spread of corrosion.
Not dangerous for people, animals, plants.
Easy to maintain and visually appealing.
Types of stainless steel
There are several types of
this material. In fact, it is an alloy, with various impurities. The most common are the following variants:
Austenitic. Contains at least 20 percent chromium and 4.5 percent nickel.
Duplex. A quarter of the composition is chromium. The amount of nickel is reduced to 1.5 percent. Nitrogen impurities are also present.
Ferritic. Percentage of chromium content is up to 29.
Martensitic. The composition of chromium is only 13 and nickel 4%.
There are also multicomponent versions. They have a minimum of the basic elements present in the compositions described above, but there are other impurities. They are selected for specific purposes.
Physical properties of stainless steel
Stainless steel has a special priority among manufacturers, not only in view of its corrosion resistance properties, but also because of its very versatile physical properties. The material is formed by mixing steel with impurities of other metals.
The physical properties of the finished raw material depend directly on the impurities added to the steel. Depending on the content of this or that element, some types of stainless steel can succumb to corrosion after some time of service. However, such compositions have their advantages, so the relative shortness loses its importance.
Stainless steel has a number of physical properties that make it of high value in some industries. These include:
The key property is anti-corrosive, which the name implies. Stainless steel is not affected by alkalis, acids or other agents.
Resistance to changes in the external environment. This steel is resistant to changes in temperature and humidity, which allows it to serve for a long time.
Products made of stainless steel are highly durable – physical loads do not bring them to disrepair so quickly as analogues made of other materials. That is why they keep working for ten years and more.
Heat resistance. Stainless steel is wear-resistant even under the influence of open fire and low temperatures.
Appearance. Steel retains its external properties even after a long period of operation, brightly shiny and easy to care for.
Depending on the purpose of using stainless steel, a particular alloy is selected. Depending on it, the above properties may vary for better or for worse. For example, there are three main subspecies of stainless steel: corrosion-resistant, heat-resistant and heat-resistant.
How to identify stainless steel
How to determine food-grade stainless steel at home if there is no possibility of laboratory analysis? There are enough methods to do it:
The use of a magnet
The method is based on Foucault currents, which do not allow the stainless steel to be magnetized. It is important to note that some compositions (iron and martensitic) are magnetic. Therefore, this solution is suitable in situations where you need to determine the grade of stainless steel, its type. And the fact that it is this kind of material is already known.
Application of saline solution
At home, the saline solution is easy to make. After that, the tested material is placed in it for a day. If there is any corrosion, then we have some other alloy in front of us.
In this way, a visual comparison can be made with brass. If outwardly they may be indistinguishable, the brass cut will be yellow rather than light gray.
Using copper sulfate
If you rub the surface with sandpaper and treat it with copper sulfate, the “impostor” will give away the external changes, while the stainless steel will remain unchanged.
The clean sheet method
An effective way to distinguish stainless steel from aluminum. A clean white sheet is taken and placed tightly against the item being tested. If it is made of aluminum, traces will remain.
This is another method. It is suitable if the object under study can be placed on a fire and water can be heated in it. It is desirable to have another one, guaranteed of stainless steel of the same volume. If the first one is made of aluminum, the water in it will boil noticeably faster.
If you have the appropriate knowledge and have access to chemicals, you can check by chemical means:
Aluminum will stain if you treat it with acid or alkali.
Carbon steel will give off corrosive fumes when it comes into contact with nitric acid.
Non-ferrous metals begin to darken if a mixture of 20% sulfide and hydrogen peroxide is used on a fresh cut.
Distinguishing characteristics of food-grade stainless steel from technical stainless steel
You can tell the difference by eye, too. The food grade variant is characterized by a smooth surface with good quality processing. You can also carefully examine the object and try to determine the grade of stainless steel by the marking supplied by the manufacturer:
08X18H10. It is possible to use in the food industry, but the manufactured utensils must not be exposed to caustic soda.
08Х13. This grade is mainly used for the production of tableware.
20CR13-40CR13. It is used for tableware and sinks. Characterized by plasticity, resistance to mechanical impact, temperature changes.
12Х13. Most often used in alcohol and wine production.
08Х17. It is used for the production of frying pans.
What does the price depend on?
The cost of this metal depends on the following factors:
Type (martensitic, austenitic, duplex, and so on).
The quality of the product.
Type of rolled metal and its thickness.