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A Comprehensive Guide to 434 Stainless Steel
434 stainless steel is a kind of ferritic stainless steel that includes chromium and molybdenum. It is a low-carbon grade of stainless steel that cannot be hardened but boasts excellent corrosion resistance, toughness, and ductility. Adding molybdenum to 434 stainless steel enhances its resistance to crevice and pitting corrosion, especially in chloride-containing environments.
434 stainless steel is a type of steel that is often used in high-temperature applications such as automotive exhaust systems, mufflers, and catalytic converters. This is because it can withstand high temperatures without losing its strength. Additionally, it is commonly used in industrial and construction applications where good corrosion resistance and a pleasing appearance are essential. In this article, we will look closer at the composition and properties of 434 stainless steel to better understand its uses, advantages, and disadvantages
Definition of 434 Stainless Steel
434 stainless steel is a popular ferritic stainless steel type that cannot be hardened. It is an improved version of 430 stainless steel, known as 10Cr17Mo. This improvement is due to adding 0.75%-1.25% molybdenum to the steel, which enhances its cutting performance, pitting corrosion resistance, crevice corrosion resistance, and overall strength. Additionally, adding molybdenum makes the steel more resistant to corrosion caused by deicing chemicals and salt solutions than 430 stainless steel.
434 stainless steel offers good heat and oxidation resistance up to 1500°F (816°C) and displays favorable mechanical properties. It is a ferritic stainless steel designed for use in the fabrication of wrought products, and its properties are suitable for the annealed condition.
Producing Process of 434 Stainless Steel
The production process of 434 stainless steel starts with creating pig iron from iron ore with the help of a blast furnace or electric furnace. Pig iron is a form of iron that has had excess carbon and other impurities removed by injecting oxygen into the molten iron. Once the pig iron’s desired carbon concentration is achieved, the melt will add 434 stainless steel alloying elements like chromium, molybdenum, silicon, manganese, etc. The molten 434 stainless steel alloy is then shaped into various forms, such as ingots, billets, and bars, and allowed to cool naturally to the ambient temperature. Further processes, such as extrusion or rolling, create additional shapes like sheets, plates, and more.
Chemical Composition of 434 Stainless Steel
The chemical compositions of 434 stainless steels are tabulated below.
| Element | Percentage(%) |
| Chromium, Cr | 16-18 |
| Molybdenum, Mo | 0.75-1.25 |
| Silicon, Si | 1 |
| Manganese, Mn | 1 |
| Carbon, C | 0.12 |
| Phosphorous, P | 0.040 |
| Sulfur, S | 0.030 |
| Iron, Fe | Balance |
The Properties of 434 Stainless Steel
Physical Properties of 434 Stainless Steel
| Property | Value |
| Density | 7.80 cm³（0.282 lb/in³） |
| Magnetism | Magnetic |
Mechanical Properties of 434 Stainless Steel
| Property (Annealed) | Value |
| Tensile strength | 538 MPa（78000 psi） |
| Yield strength (@ strain 0.200%) | 441 MPa（64000 psi） |
| Elastic modulus | 200 GPa（29008 ksi） |
| Poisson’s ratio | 0.27-0.30（0.27-0.30） |
| Elongation at break (in 50 mm) | 32% |
| Reduction in Area | 78% |
| Hardness, Rockwell B (converted from Brinell hardness) | 89 |
Thermal Properties of 434 Stainless Steel
| Property | Value |
| Melting Point | 1510°C（2750°F） |
| Thermal Expansion Coefficient | 10.4 μm/m-°C (0-100°C) |
| Thermal Conductivity | 26.1 (@100°C) – 26.3 (@500°C) W/mK |
| Specific Heat | 460 J/kg-K (0-100°C) |
| Electric Resistivity | 60 μ ohm.cm at 20°C |
Some other properties of 434 stainless steel:
Machinability
434 stainless steel exhibits good machinability in standard processing methods, such as cutting, drilling, milling, and turning. It can achieve excellent cutting performance under high load, making the machining process relatively effortless.
Stability
434 stainless steel can maintain its mechanical properties and corrosion resistance under high-temperature conditions, making it suitable for high-temperature cutting and machining processes without causing changes in its properties or color.
Forming
Due to its high ductility, blanking, shearing, and deep drawing operations can be successfully performed.
Welding
Stainless steel type 434 has commendable welding properties and can be joined using conventional welding techniques like arc welding, laser welding, and TIG welding. It also has a low risk of thermal cracking, making the welding process more accessible.
Cutting
434 stainless steel is low-hardness, making it easier to cut. This means that cutting tools can remove material quickly without prematurely wearing out. Moreover, 434 stainless steel offers higher cutting speed and feed rate, which can result in improved production efficiency.
Forging
Grade 434 stainless steel can be forged at a temperature range of 1094-1149°C (2000-2100°F) after it has been soaked thoroughly.
Annealing
Grade 434 stainless steel undergoes annealing by heating to 788-872°C (1450-1600°F), followed by cooling in air.
Hardening
Grade 434 stainless steel cannot be hardened by heat treatment.
Characteristics of 434 Stainless Steel
Strength and Durability
434 stainless steel is prevalent due to its exceptional strength and durability. Its excellent tensile strength makes it perfect for high-stress resistance applications. Moreover, this type of stainless steel has outstanding creep strength, which means it can withstand higher temperatures without deforming or breaking down over time. Apart from its durability, this stainless steel also has good ductility, making it easy to form complex shapes when required.
Resistance to Corrosion
Type 434 stainless steel is known for its outstanding resistance to corrosion, which is superior to other types of stainless steel. It has been extensively tested in various environments, including humid air and saltwater, and has shown remarkable corrosion resistance even under these harsh conditions. This makes it an excellent choice for applications where corrosion is a concern, such as pipes or medical instruments that require sterility.
Heat Resistance
434 stainless steel stands out for its remarkable corrosion resistance and excellent heat resistance compared to other metals. With a melting point of approximately 2700°F (1482°C), it can withstand higher temperatures without losing shape or getting damaged over time. This makes it ideal for high-temperature applications such as nuclear reactors or exhaust systems, where effective heat management is a top priority.
Formability
It is incredibly malleable and can be easily formed through various fabrication processes, including stamping, drawing, and shaping.
Equivalent Forms of 434 Stainless Steel
| Country | Equivalent Grade |
| France | AFNOR Z 8 CD 17.01 |
| Germany | DIN 1.4113 |
| Italy | UNI X 8 CrMo 17 |
| Japan | JIS SUS 434 |
| Sweden | SS 2325 |
| United Kingdom | B.S. 434 S 19 |
| United States | AISI 434 |
Equivalent-Grade Steels from Different Countries
Common Forms of 434 Stainless Steel
AISI 434 is available in various shapes suitable for different applications, including the following common forms of 434 stainless steel:
Bar
Type 434 stainless steel bars can be manufactured by continuously casting the molten alloy, extruding or rolling, and extruding 434 ingots. The bars can take on a variety of shapes, including square, rectangular, circular, hollow tubes, and hexagonal shapes. Cold rolling can strengthen the bars by altering the material’s microstructure and forcing the steel atoms to dislocate. If necessary, annealing and hot-rolling can be used after cold-working to restore the bars to their original material properties. These bars are perfect for making machined parts.
Plate
A stainless steel plate, identified as SAE 434, is produced by hot or cold rolling the material through several rollers to attain the required thickness and dimensions. The thickness of the SAE 434 plate generally falls between 6 and 25 mm. 434 stainless steel plates are often processed into parts or assemblies using welding and plasma cutting.
Sheet
Type 434 stainless steel sheets are similar to plates but thinner. They are manufactured using either hot rolling or cold rolling methods until the desired thickness and dimensions are achieved. The thickness of 434 stainless steel sheets can vary from 0.1 to 6 mm. Sheets are highly flexible and are suitable for lighter applications that do not require high load-bearing capacity.
Hot Rolled
Hot rolling is a metal-forming process that involves heating the metal to a temperature higher than its recrystallization point and then passing it between two rollers to deform it plastically. This deformation process decreases the metal’s cross-sectional area, prompting atoms in the microstructure to move around. Hot-rolled 434 steel is available in various forms, such as plates, sheets, and rectangular and round bars.
Annealed
Annealing is a heat treatment process utilized to increase the ductility and decrease the hardness of materials. The process involves heating 434 stainless steel to a temperature above its recrystallization temperature and holding it there for some time. After heating, the metal is allowed to cool to room temperature. Annealing causes atoms in the microstructure to rearrange and reduces the number of dislocations. Recrystallization occurs as the metal cools, producing a more ductile and less hard material.
Cold Drawn
Cold drawing is a cold working process that permanently deforms a material at room temperature to form and strengthen it. This process is typically carried out after annealing and involves forcing the material through an extrusion die. The dislocation of atoms in the material’s microstructure at room temperature causes an alteration in its crystal lattice structure, resulting in increased strength and hardness.
Applications of 434 Stainless Steel
434 stainless steel is widely used in various applications due to its remarkable mechanical properties and corrosion resistance. Below are some common application areas of this type of steel:
Automotive industry
434 stainless steel is a widely used material in the automobile industry. It is commonly employed in fabricating components for exhaust systems, such as exhaust pipes, and various automotive parts, such as crankshafts, camshafts, bolts, and fasteners. Its distinguished resistance to high temperatures, corrosion, and mechanical stress makes it an excellent choice for these applications.
Chemical industry
434 stainless steel is commonly used to manufacture chemical industry equipment, including containers, storage tanks, pump bodies, heat exchangers, and pipelines. It is resistant to various chemicals and maintains a long life in harsh working environments.
Food processing
434 stainless steel is commonly used in food processing equipment due to its corrosion resistance and hygienic properties. This includes food containers, conditioning machinery, transportation equipment, and heating equipment.
Medical devices
434 stainless steel is a popular material used to produce medical devices and equipment, such as surgical tools, injection needles, implants, and clavicle plates. This material is chosen for its excellent corrosion resistance and biocompatibility, which makes it a perfect fit for the medical industry.
Ocean engineering
434 stainless steel is commonly used in ocean engineering equipment and components, such as ships’ structural parts, offshore platforms, seawater treatment equipment, and valves. Its excellent corrosion resistance to saltwater environments makes it a popular choice.
Oil and gas industry
434 stainless steel is widely used in the oil and gas industry, particularly in the extraction, processing, and storage of oil. This type of steel is commonly employed in producing oil drilling pipelines, oil pipelines, chemical equipment, and storage tanks, among other applications. Because of its outstanding resistance to corrosion and durability, it has a significantly longer lifespan in harsh and corrosive environments.
Besides the previously mentioned fields of application, 434 stainless steel can also be utilized to produce heat exchangers, electronic components, home decorations, aerospace, and electrical equipment. The use of this type of stainless steel in these areas highlights its significance and versatility in diverse industries.
Advantages & Disadvantages
Advantages:
- It has excellent corrosion resistance.
- It has minimal expansion compared to austenitic stainless steel due to its low coefficient of thermal expansion.
- It is chemically stable and does not readily react with solvents and cleaning agents, making cleaning 434 stainless steel very easy.
- It possesses high strength when compared to materials such as 1090 mild steel or A36 steel.
- In contrast to other commonly used stainless steel grades like 304 or 316, 434 stainless steel is magnetic. This property makes it ideal for applications that request magnetic properties, such as solenoids, fuel injectors, and motors.
Disadvantages:
- 434 stainless steel is more costly than carbon steel and other metals, such as aluminum, due to its alloying elements and higher production costs.
- While 434 stainless steel has higher thermal conductivity than some other stainless steels, it has lower thermal conductivity than materials like copper and aluminum. Therefore, there are better material choices for applications that require rapid heat transfer.
Comparison
434 Stainless Steel & 304 Stainless Steel
Due to their compositions and properties, there are significant differences between 434 stainless steel and 304 stainless steel. 434 stainless steel is ferritic, while 304 is austenitic type. This means 434 stainless steel has a ferritic microstructure because of its lower chromium and nickel concentrations, while 304 stainless steel is austenitic. As a result, 434 stainless steel is magnetic while 304 stainless steel is not. Moreover, 434 stainless steel has a lower concentration of chromium and nickel than 304 SS. The lower chromium concentration and higher carbon content in 434 stainless steel make it less corrosion-resistant but stronger than 304 stainless steel.
434 Stainless Steel & 316 Stainless Steel
The differences between 434 stainless steel and 304 stainless steel, as well as 434 and 316, can be attributed to their chemical compositions. Type 434 stainless steel is a ferritic stainless steel, which makes it magnetic, while 316 stainless steel, similar to 304, is an austenitic stainless steel and is not magnetic. Although 434 and 316 have similar chromium concentrations, 316 is considered more corrosion-resistant due to its higher nickel and molybdenum concentrations.
Summary
434 stainless steel is a highly versatile material that offers multiple advantages over other metal alloys. It has excellent strength, durability, corrosion resistance, and heat resistance properties. Whether you need it for an automotive component or something more aesthetically pleasing for an architectural project, 434 stainless steel should definitely be on your list of materials. With proper care and maintenance, this type of metal can provide years of reliable service, with minimal maintenance required throughout its lifetime.