Applicable standards and approvals
AMS 5513
ASTM A 240
ASTM A 666
Classification
corrosion-resistant, heat-resistant steel
Application
- Household items
- Sinks
- Frames for metal structures in the construction industry
- Kitchen utensils and catering equipment
- Dairy equipment, brewing
- Welded structures
- Tanks on ships and land tankers for food, beverages and some chemicals
Typically, steel manufacturers divide the grade into three main classes (grades) according to their drawing ability:
- AISI 304- Main variety
- AISI 304 DDQ(Normal and deep drawing) - Deep drawing variety
- AISI 304 DDS(Extra deep drawing) - Extra deep drawing variety
Main characteristics
- good overall corrosion resistance
- good ductility
- excellent weldability
Chemical composition (% by weight)
Mechanical properties at high temperatures
All these values apply only AISI 304.
Physical properties
| Physical properties | Legend | Unit | Temperature | Meaning |
|---|---|---|---|---|
| Density | d | - | 4°C | 7.93 |
| Melting temperature | °C | 1450 | ||
| Specific heat | c | J/kg.K | 20°C | 500 |
| Thermal expansion | k | W/m.K | 20°C | 15 |
| Average coefficient of thermal expansion | α | 10 -6 .K -1 | 0-100°C 0-200°C |
17.5 18 |
| Electrical resistivity | ρ | Ωmm 2 /m | 20°C | 0.80 |
| Magnetic permeability | μ | at 0.80 kA/m DC or military unit AC |
20°C μ μ discharge air |
1.02 |
| Elastic modulus | E | MPa x 10 3 | 20°C | 200 |
Corrosion resistance
304th steels have good resistance to general corrosive environments, but are not recommended where there is a risk of intergranular corrosion. They are well suited for use in fresh water and urban and rural environments. In all cases, regular cleaning is necessary external surfaces to maintain their original condition.
304th steels have good resistance various acids:
- phosphoric acid in all concentrations at temperature environment,
- nitric acid up to 65% at a temperature of 20°C - 50°C,
- formic and lactic acid with room temperature,
- acetic acid at a temperature of 20°C - 50°C.
Acidic environments
| Temperature, °C | 20 | 80 | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Concentration, % by weight | 10 | 20 | 40 | 60 | 80 | 100 | 10 | 20 | 40 | 60 | 80 | 100 |
| Sulfuric acid | 2 | 2 | 2 | 2 | 1 | 0 | 2 | 2 | 2 | 2 | 2 | 2 |
| Nitric acid | 0 | 0 | 0 | 0 | 2 | 0 | 0 | 0 | 0 | 0 | 1 | 2 |
| Phosphoric acid | 0 | 0 | 0 | 0 | 0 | 2 | 0 | 0 | 0 | 0 | 1 | 2 |
| Formic acid | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 2 | 2 | 1 | 0 |
Code: 0 = high degree protection - Corrosion rate less than 100 µm/year
1 = partial protection - Corrosion rate from 100 to 1000 µm/year
2 = no protection - Corrosion rate more than 1000 µm/year
Atmospheric influences
Comparison 304th grades with other metals in various environments (Corrosion rate calculated for 10-year exposure).
Resistant to corrosion in boiling chemicals
| Boiling medium | Metal condition | Corrosion rate (mm/year) |
|---|---|---|
| 20% acetic acid | Regular metal Welded |
<0.01 0.03 |
| 45% formic acid | Regular metal Welded |
1.4 1.3 |
| 10% sulfamic acid | Regular metal Welded |
3.7 3.7 |
| 1% hydrochloric acid | Regular metal Welded |
2.5 2.8 |
| 20% phosphoric acid | Regular metal Welded |
<0.03 <0.03 |
| 65% nitric acid | Regular metal Welded |
0.2 0.2 |
| 10% sulfuric acid | Regular metal Welded |
11.3 12.5 |
| 50% sodium hydroxide | Regular metal Welded |
3.0 3.3 |
The reason for the vulnerability of austenitic stainless steels in the temperature range 425°C - 820°C is the precipitation of chromium carbides at the grain boundaries. Such steels become “sensitized” and become susceptible to intergranular corrosion in aggressive environments. The carbon content in AISI 304 grade can cause sensitization from thermal conditions in welds and their heat-affected zones.
Test for ICC (Intercrystalline corrosion)
Welding
- The steel is easy to weld.
- No heat treatment is required after welding.
- Welds must be mechanically or chemically descaled and then passivated.
Molding
Steel grade AISI 304, being extremely durable, elastic and plastic, easily finds many applications. Typical operations include bending, contouring, drawing, rotary drawing, etc. The forming process can use the same machines and, most often, the same tools as carbon steel, but requires 50-100% more force. This is due to the high degree of hardening during forming of austenitic steel, which in some cases is a negative factor.
Additional varieties are produced AISI 304 DDQ And AISI 304 DDS for deep and extra deep drawing.
About stretch molding
In the stretch forming process, the workpiece is subjected to “braking” during stretching. The walls become thinner, and to avoid tearing, it has become desirable to provide increased strength properties during molding.
The degree of elongation is determined by the Erickson stretch test (deformation is carried out before the walls begin to thin).
Deep Drawing Tests
In clean deep drawing on a press, the workpiece is not subjected to “braking”, and the material is allowed to flow freely in the tools. In practice this happens very rarely. For example, when drawing household utensils, there is always also an element of stretch forming.
The characteristics of sheet material during deep drawing are described by the limiting drawing ratio - LDR (the ratio of the largest possible diameter of the sample before the moment of rupture to the diameter of the press) and the scalloping limit (in the forming test - the relative size of the formed tongues).
Eriksen extrusion test
*Limiting drawing ratio - limiting drawing ratio
Scalloping assessment
Bending
Approximate bending limits:
- s< 3мм → мин r = 0
- 3mm< s < 6мм → мин r = ½ s, угол 180°
- 6mm< s < 12мм → мин r = ½ s, угол 90°
The reverse straightening is greater than that of carbon steel, which is why “the bending should be correspondingly greater.” When bending a regular right angle by 90º, we get the following straightening indicators:
- r = s reverse straightening about 2°
- r = 6s reverse straightening about 4°
- r = 20s reverse straightening approx. 15°
For austenitic stainless steel (incl. AISI 304) the minimum recommended bending radius is r = 2s, where s is the sheet thickness.
Treatment
Annealing
The annealing temperature range is 1050°C ± 25°C followed by rapid cooling in air or water. The best corrosion resistance is achieved by annealing at 1070 °C and rapid cooling. After annealing, etching and passivation are necessary.
Vacation
For AISI 304L- 450-600 °C for one hour with a slight risk of sensitization. For AISI 304 A lower tempering temperature should be used - a maximum of 400 °C.
Any hot processing must be accompanied by annealing.
Particular attention should be paid to the following fact: for stainless steel, uniform heating requires a time that is 2 times longer than the time for the same thickness of carbon steel.
Etching (surface cleaning)
- Mixture of nitric acid and hydrofluoric acid (10% HNO3 + 2% HF) at room temperature or 60°C
- Sulfur-nitric acid mixture (10% H 2 SO 4 + 0.5% HNO 3) at 60°C
- Paste for descaling in the welding zone
Passivation
- 20-25% HNO 3 solution at 20°C
- Passivation pastes for the welding zone
At the beginning of the last century, specialists in the metallurgical industry were able to notice that the interaction of chromium and oxygen is better than with iron. It was at that time that in order for the air to have the least effect on iron, metallurgists began to mix it with chromium. This is how stainless steel appeared, which today is an indispensable material for modern industry.
Important: It should be noted that it is practically impossible to completely rid iron of corrosion. Sooner or later, even stainless steel also becomes covered with rust. True, this requires more time.
Stainless steel is an attractive material for use in modern industry. It consists of iron and chromium impurities.
Attention: In order to ensure the longest possible protection of iron from corrosion, it is necessary to add at least ten percent chromium to it during the production of stainless steel.
Also, other elements are added to the mixture for the production of stainless steel, which are presented:
- nickel,
- niobium,
- molybdenum,
- titanium.
They are necessary for the material to acquire its physical and chemical qualities and become more durable.
Thanks to the mixture of iron and other elements, a material is created that can resist corrosion. Depending on the proportionality of the added elements, the stainless material becomes durable and can withstand even high temperatures. Due to its ductility, stainless steel is used in a wide variety of industries.
Iron itself becomes rusty quite quickly. If you mix it with chromium and other elements, an invisible film is formed on its surface, which prevents the flow of oxygen to it. As a result, no oxidation occurs. This layer is quite durable. Which makes the material more resistant to the formation of cracks, dents and many other defects. Steel can repair itself over time.
Stainless steel grades and their characteristics
In the modern world there are more than two hundred and fifty types of stainless steel. They differ in their series or brands and in their properties. The most popular grades of stainless steel currently are those types that belong to the 300 and 400 series. They have a high level of resistance to corrosion. In addition, their layer of protective film is quite durable due to the optimally selected proportionality of the elements used in production. Stainless steel of these series has high strength and ductility. It is actively used for the production of various items in modern industry. Soon, these series may be competed by the 200 series of steel, which, according to consumers, has the optimal combination of cost and quality.
Characteristics of AISI stainless steels
In the modern market, stainless steel of the 300 series is in great demand. It is divided into several types depending on the chemical composition:
- austenitic,
- austenitic-ferritic,
- austenitic-martensitic.
These types of steel contain different amounts of nickel and chromium. carbon. 
AISI 304 stainless steel
aisi 304 (08Х18Н10) is widely used in the food industry. It is excellent for welding and to resist rust. 
AISI 316 stainless steel
aisi 316 (10Х17Н13М2) is formed if an element such as molybdenum is added to aisi 304 (08Х18Н10) steel. This grade of stainless steel is widely used in the shipbuilding, oil and gas and chemical industries. It is resistant to aggressive environments.
AISI 316T stainless steel
aisi 316T (10Х17Н13М2Т) о has a high level of strength due to the fact that it contains more titanium than previous brands. It has found wide application in the creation of equipment for the chemical and food industries.
AISI 321 stainless steel
aisi 321 (12-08Х18Н10Т) with the largest amount of titanium among all brands of the three hundredth series. Able to withstand heating temperatures up to 800 degrees Celsius.
AISI 430 stainless steel
Among the brands of the four hundredth series, the most widely used brand is aisi 430 (12X17). In general, the entire series is characterized by the fact that it includes stainless steel grades that are created with a high chromium content. The characteristic feature of the aisi 430 brand is that the material bends well and is subject to welding. This steel can be used for places with high temperature changes. Most often it is used for decoration of buildings and in the oil and gas industry.
Stainless steel AISI 201
The 200 series of stainless steel also has worthy brands that you should pay attention to. Among them, the most prominent steel is AISI 201 (12X15G9ND). It differs from more expensive brands from other series in that it uses a mixture of elements such as nitrogen and manganese instead of nickel. Due to its chemical and physical properties, it is widely used in the food and medical industries. It is also suitable for the production of various types of fences and pipes.
| Stainless steel standards | Content of alloying elements, % | |||||||||
| * | DIN | AISI | GOST | C | Mn | Si | Cr | Ni | Mo | Ti |
| C1 | 1.4021 | |||||||||
| F1 | 1.4016 | |||||||||
| A2 | 1.4301 | |||||||||
| 1.4948 | ||||||||||
| 1.4306 | ||||||||||
| A3 | 1.4541 | |||||||||
| A4 | 1.4401 | |||||||||
| 1.4435 | ||||||||||
| 1.4404 | ||||||||||
| A5 | 1.4571 | |||||||||
| 1.4845 | ||||||||||
Stainless steel standards
There are state standards for different types of stainless steel in our country. They determine the quality of products made from this material. Stainless steel has different GOST standards. Certain quality standards are developed for thin sheets, for wire, for thick sheets and for stainless steel pipes.
Stainless steel has different characteristics. Thanks to its chemical and physical parameters, it easily resists the formation of corrosion plaque. This material was developed for use in places where there are different environmental conditions. Due to its heat resistance and strength, steel does not react with substances in the environment.
Modern industry cannot do without the use of stainless steel. It is not only a high-strength material, but also has an attractive appearance. It was because of its beauty that steel began to be used for the decoration of buildings and their individual elements. In particular, fencing and railings for staircases are made from stainless steel.
In the food industry, rolled steel is very popular. Cooking equipment and utensils are made from steel materials. They are able to withstand high heating temperatures and are not susceptible to rust.
The use of stainless steel in the chemical industry began in the middle of the last century. The most durable types of steel material are used here so that equipment or devices do not fail under the influence of various reagents.
Articles on the topic
Of course, there is no real gold or silver in modern metallic printing inks. But they very successfully imitate noble metals, since one third consists of metallic pigments of silver or golden color.
Today, many people are faced with the formation of rust on metal surfaces. It is formed under the influence of the environment. The process of formation of rusty plaque can have different durations.
In the modern world, stainless steel is an indispensable material in the production of different types of products. It is used in the food, medical, metallurgical and military industries.
APEX METAL offers customers a variety of types of stainless steel products made from the best grades of stainless steel that meet strict international standards and have excellent technological and performance characteristics. High corrosion resistance of stainless steel is the main characteristic of products made from these materials for long-term operation in aggressive corrosive environments, over wide temperature ranges.
The chemical composition of rolled products made of corrosion-resistant stainless steel AISI 304 of the austenitic class meets the requirements of the AISI standard - American Iron and Steell Institute (American Institute of Steel and Alloys). In accompanying documents, the designation of AISI stainless steel grades and its analogues is made in accordance with national or international standards:
| National standard | Stainless steel grade | |||
|---|---|---|---|---|
| AISI USA | steel AISI 304 | steel AISI 321 | steel AISI 316 | steel AISI 430 |
| RF standard | 08Х18Н10 | 12Х18Н10Т | 08Х17Н13М2 | 12Х17 |
| EN Europe | 1.4301 | 1.4541 | 1.4436 | 1.4016 |
| UNS USA | S30400 | S32100 | S31600 | S43000 |
| SIS Sweden | 2332/33 | 2337 | 2343 | 2320 |
| BS UK | 304S31 | 321S31 | 316S33 | 430S17 |
| JIS Japan | SUS304 | SUS321 | SUS316 | SUS430 |
| DIN Germany | X5CrNi18-10 | X10CrNiTi18-10 | X3CrNiMo18-3-4 | X6Cr17 |
What information can be found by the designation of stainless steel grades
The stainless properties of steel are due to the presence of alloying elements in its composition, the main of which are chromium and nickel. To impart special properties (greater strength, cold resistance, etc.) and improve technological characteristics, other alloying elements (for example, titanium, molybdenum, manganese), and nanoadditives of rare earth metals are added to steel.
Thanks to titanium alloying, stainless steel 12x18n10t acquires increased cold resistance and is used for the manufacture of welded products for cryogenic equipment operating at temperatures down to -269˚C. In addition, by the symbol of steel grades you can determine:
- The chemical composition of steel, for example, chromium stainless steel X6Cr17 - aisi 430 contains up to 0.08% mass fraction of carbon (the number 6 after the letter X indicates the average carbon content in steel, multiplied by 100) and 16 - 18% chromium
- Steel class, for example, the number 3 in the designation of AISI 316 stainless steel indicates that it belongs to the austenitic class. Accordingly, the number 4 in the designation of steel 430 indicates that the steel belongs to the ferritic class, the next two digits determine the serial number of the steel in the group
- The European standard indicates that stainless steel belongs to a certain type; by the serial numbers of steels 1.4301, 1.4436, 1.4016, it can be determined that the grades in question belong to the group of stainless steels (this group includes steels numbered 1.40ХХ-1.45ХХ)
- The letter S in the designation of steel according to the UNS standard indicates that the material belongs to the group of heat-resistant and corrosion-resistant (stainless) steels (this group includes steels designated S00001...S99999)
- In the designation of steel according to the Swedish standard, the numbers 23ХХ indicate the chromium content in the steel (all grades discussed in the table belong to the group of steels with a chromium content ≥10%)
- In the standards in force in the Russian Federation, By The symbol of steel can be used to judge its elemental composition; regulatory documents for stainless steel (GOST 5632 and others) provide information on the classification of steel, chemical composition, properties, purpose and areas of application
- In the designation of steel according to the Swedish standard, the numbers 23XX indicate chromium ≥10%)
- In the standards in force on the territory of the Russian Federation, by the symbol of steel one can judge its elemental
One of the most popular steel grades is AISI 304. Steel of this grade belongs to the austenitic group. The austenitic group is characterized by high density and ductility, as well as resistance to corrosion and temperature changes. The carbon content in this grade of stainless steel does not exceed 0.08%, while the chromium and nickel content ratio ranges from 18-20% and 8-10.5%.
The AISI marking system was developed by the American Iron and Steel Institute and is one of the most common in the world. It is used for labeling products and raw materials imported into the countries of Asia and Eastern Europe, along with national systems. In our country, AISI 304 corresponds to brand 08Х18Н10.
AISI 304 steel type is characterized by the presence of a thin layer of chromium oxide on the surface. This layer reliably protects the product from corrosion even under the influence of aggressive chemicals, food essences, water, soil, sudden temperature changes, etc. Unlike other types of steel, AISI 304 stainless steel can be welded without any restrictions.
AISI 304 is a stainless steel with a low percentage of carbon. Due to the versatility of its physical characteristics, this steel grade is one of the most popular not only in Russia, but also in other countries near and far abroad. AISI 304 steel grade is used to make equipment that is used in catering, food and chemical industries.
In addition, equipment for storing and transporting chemicals, wine, beer, and milk is made from this stainless steel. In addition, cutlery and kitchen utensils, architectural parts and pipes are made from AISI steel. Due to the fact that this steel does not accept hardening, it is not suitable for knife production.
Steel composition:
C 0.08%- carbon content in the alloy is 0.08%. Carbon is the most important element in steel; it increases its strength and gives the metal good hardness.
Сr 18.0 - 20.0%- chromium content in the alloy is 18.0 - 20.0%. Chrome is a greyish-white, shiny hard metal. Chromium affects the ability of steel to harden, gives the alloy anti-corrosion properties and increases its wear resistance. Contained in stainless steel of any grade.
Mn 2.0%- the manganese content in the alloy is 2.0%. Manganese is used at the steelmaking stage. Capable of increasing the hardness of steel. Various durable things are made from steels with a significant manganese content - rails, safes, and so on.
NI 8.0 - 10.5%- nickel content in the alloy - 8.0 - 10.5%. Nickel increases the corrosion resistance of steel and can slightly increase strength.
Si 1.00%- silicon content in the alloy - 1.00%. Silicon increases the strength and wear resistance of steel. Like manganese, it makes steel more stable and reliable.
P 0.045%- phosphorus content in the alloy - 0.045%. Phosphorus is one of the harmful technological impurities in steels and alloys. Increasing its content even by a fraction of a percent, while increasing strength, simultaneously increases fragility. The harmful effects of phosphorus are especially pronounced at high carbon levels. The limits for phosphorus content as a technological impurity are 0.025...0.045%.
S 0.03%- sulfur content in the alloy - 0.03%. Sulfur, like phosphorus, is a harmful technological impurity in steels and alloys. An increase in sulfur content significantly reduces the mechanical and physicochemical properties of steels, in particular, ductility, impact strength, abrasion resistance and corrosion resistance. The limits for sulfur content as a technological impurity are 0.035...0.06%.
1 product with this characteristic was found in the catalog.
Loading...