Вступ
Нержавіюча сталь is a widely used material known for its exceptional properties such as durability, міцність, and resistance to corrosion.
It is utilized across various industries, from construction and automotive to medical devices and kitchen appliances.
Selecting the appropriate type of stainless steel ensures optimal performance and longevity in different applications. This guide provides an in-depth overview of the different kinds of stainless steel, their characteristics, and suitable applications.
1. Що таке нержавіюча сталь?
Stainless steel is an alloy made primarily of iron and at least 10.5% хром, giving it distinctive corrosion resistance. The addition of chromium allows for the formation of a thin, protective oxide layer on the steel surface, preventing rust and oxidation.
Other elements like nickel, молібден, and manganese may also be added to enhance specific properties such as strength, пластичність, and resistance to heat and chemicals.
Common Properties of Stainless Steel:
- Корозійна стійкість: The chromium element in stainless steel reacts with oxygen to form a dense sodium chromate layer, which effectively reduces the probability of corrosion and makes stainless steel have good corrosion resistance.
- Heat resistance: Stainless steel can maintain excellent physical and mechanical properties at high temperatures, has good heat resistance, and can maintain good physical and chemical properties in different temperature environments.
- висока сила: Stainless steel has high strength and can withstand greater pressure and tension.
- Safety and hygiene: Stainless steel does not contain radioactive substances and will not cause any harm to the human body. It is suitable for food production equipment or production lines and other devices.
- Beautiful surface: The surface of stainless steel is bright, Легко очистити, and has low maintenance costs1.
- Good machinability: Stainless steel can be formed and processed in a variety of ways, such as welding, cold processing, precision processing, тощо.
- Recyclability: Stainless steel materials can be recycled and have little impact on the environment.
- Good elasticity and plasticity: Stainless steel materials have good elasticity and plasticity and are not prone to breakage.
These characteristics make stainless steel widely used in various fields, such as machinery, aviation, military industry, хімічна промисловість, тощо.
2. Види нержавіючої сталі
Stainless steel is divided into five main families, each with unique microstructures and chemical compositions that impart distinct properties. Understanding these classifications is crucial for selecting the right material for various applications, from kitchen appliances to aerospace components. Here’s an in-depth look at each type:
1. Аустенітна нержавіюча сталь
Structure:
Austenitic stainless steel has a face-centered cubic (FCC) кристалічна структура, which is stable at room temperature. This structure makes it non-magnetic and highly ductile.
Склад:
These steels typically contain 16-26% хром і 6-22% нікель, with some grades also containing molybdenum or nitrogen to enhance corrosion resistance. Low carbon content (usually less than 0.1%) prevents carbide precipitation, which can cause intergranular corrosion.
Властивості:
Austenitic stainless steels are known for their excellent corrosion resistance, especially in acidic and chloride-rich environments. They offer good formability and weldability, making them suitable for complex shapes and large structures. Однак, they cannot be hardened by heat treatment; замість цього, they are often cold-worked to increase strength.
Загальні оцінки:
- 304: Also known as 18/8 нержавіюча сталь, this is the most widely used grade due to its versatility and excellent corrosion resistance.
- 316: Contains molybdenum, which provides superior resistance to pitting and crevice corrosion in marine and chemical environments.
- 310: High temperature-resistant steel used in furnace parts and heat exchangers.
Заявки:
Austenitic stainless steels are found in a wide range of products, including kitchen sinks, харчове обладнання, chemical tanks, and architectural facades.
2. Ферритна нержавіюча сталь
Structure:
Ferritic stainless steel has a body-centered cubic (BCC) структура, similar to that of carbon steel, which makes it magnetic and less ductile than austenitic grades.
Склад:
Typically containing 10.5-30% chromium and very low carbon (менше 0.1%), these steels have little to no nickel, making them more cost-effective than austenitic varieties.
Властивості:
Ferritic stainless steels provide good corrosion resistance and are resistant to stress corrosion cracking. They have better thermal conductivity than austenitic grades but are less suitable for welding and forming.
Загальні оцінки:
- 430: Commonly used in automotive trims and appliance panels due to its good corrosion resistance and formability.
- 409: Contains lower chromium content, offering moderate corrosion resistance, often used in automotive exhaust systems.
Заявки:
Ferritic stainless steels are often used in automotive applications, промислове обладнання, і декоративне оздоблення.
3. Мартенситна нержавіюча сталь
Structure:
Martensitic stainless steel has a body-centered tetragonal (BCT) структура. It is magnetic and can be heat-treated to achieve high strength and hardness.
Склад:
These steels contain 12-18% хром, 0.1-1.2% вуглець, and little to no nickel. The high carbon content allows them to be hardened and tempered.
Властивості:
Martensitic stainless steels are characterized by high strength, твердість, and moderate corrosion resistance. They can be heat-treated to achieve a wide range of mechanical properties but are more brittle and less corrosion-resistant than other stainless steel families.
Загальні оцінки:
- 410: General-purpose grade offering good corrosion resistance and high mechanical strength.
- 420: Often used for cutlery due to its ability to be polished to a high shine and maintained sharp edges.
- 440C: High carbon content makes it suitable for high-wear applications.
Заявки:
Martensitic stainless steels are used in knife blades, хірургічні інструменти, вали, і клапани.
4. Дуплексна нержавіюча сталь
Structure:
Duplex stainless steel has a mixed microstructure of austenite and ferrite, typically in a 50:50 ratio. This dual-phase structure gives it unique properties.
Склад:
Duplex steels typically contain 18-28% хром, 4.5-8% нікель, і до 5% молібден, з низьким вмістом вуглецю. The balanced composition reduces susceptibility to stress corrosion cracking and increases mechanical strength.
Властивості:
These steels combine the best attributes of austenitic and ferritic grades, offering high strength, Відмінна резистентність до корозії, і хороша зварюваність. They perform well in harsh environments, such as those exposed to chloride and sulfuric acid.
Загальні оцінки:
- 2205: The most widely used duplex grade, known for high strength and resistance to stress corrosion cracking.
- 2507: Super duplex grade offering even higher strength and corrosion resistance.
Заявки:
Duplex stainless steels are used in chemical processing, oil and gas industries, Морські програми, і теплообмінники.
5. Преципітаційне зміцнення (РН) Нержавіюча сталь
Structure:
PH stainless steels have a unique microstructure that allows them to be heat-treated to achieve high strength and toughness. They start as austenitic or martensitic and undergo precipitation hardening to form fine particles that increase strength.
Склад:
These steels are alloyed with elements like aluminum, мідь, і титан, which form intermetallic compounds that precipitate during heat treatment.
Властивості:
PH stainless steels offer a combination of high strength, Хороша резистентність до корозії, і відмінні механічні властивості. They can be heat-treated to various strength levels, making them versatile for many demanding applications.
Загальні оцінки:
- 17-4 РН: The most widely used PH grade, combining high strength and moderate corrosion resistance.
- 15-5 РН: Offers improved toughness over 17-4 PH and is often used in aerospace applications.
Заявки:
PH stainless steels are used in aerospace components, high-performance valves, шестерні, and other precision engineering parts.
Висновок
Understanding the various types of stainless steel is crucial for making informed decisions in material selection.
Each type offers unique properties tailored to specific applications, whether it’s the corrosion resistance of austenitic stainless steel or the high strength of martensitic grades.
Choosing the right types of stainless steel can enhance product performance, довговічність, і економічна ефективність, making it an invaluable material across industries.
Поширені запитання
Q: What are the most commonly used types of stainless steel?
A: The most commonly used type is 304 нержавіюча сталь, known for its versatility and excellent corrosion resistance
Q: Нержавіюча сталь може іржавіти?
A: Stainless steel can rust under extreme conditions such as prolonged exposure to chlorides or lack of maintenance. Однак, it is generally highly resistant to rust compared to regular steel.
Q: What is the difference between 304 і 316 нержавіюча сталь?
A: 304 stainless steel is the most widely used grade, в той час 316 has added molybdenum, providing greater resistance to corrosion, particularly in marine and chemical environments.
