Type 321 stainless steel is a titanium-rich austenitic chromium-nickel alloy recommended for parts that require welding and cannot be subsequently annealed. Similar to Type 304 stainless steel, Type 321 is a stabilized austenitic stainless steel but with the addition of titanium. This titanium addition reduces or prevents carbide precipitation during welding and service at 800-1500°F (427-816°C). It also improves the high temperature properties of the alloy. Type 321 stainless steel has excellent resistance to oxidation and corrosion and has good creep strength.
321 stainless steel chemical composition
For stainless steels, chemical composition plays a vital role in determining their properties and suitability for various applications. In the case of 321 stainless steel, its composition sets it apart from other grades. The specific chemical composition is as follows:
Mechanical properties of 321 stainless steel
321 stainless steel is a high-strength, corrosion-resistant stainless steel material. The following are the mechanical properties of 321 stainless steel:
Ultimate tensile strength
Physical properties of 321 stainless steel
The physical properties of 321 stainless steel make it a popular material for a variety of applications. Let’s take a closer look at some of its key features.
Density: 0.29 lbs/in3 9.01 g/cm3
Resistivity: microhm-in (microhm-cm): 68 °F (20 °C): 28.4 (72)
Specific Heat: BTU/lb/°F (kJ/kg•K):
32 – 212°F (0 – 100°C): 0.12 (0.50)
Thermal Conductivity: BTU/hr/ft2/ft/°F (W/ m•K):
At 212°F (100°C): 9.3 (16.0)
At 932°F (500°C): 12.8 (22.0)
Average Coefficient of Thermal Expansion: in/in/°F (µm/m• K)
32 – 212 °F (0 – 100 °C): 9.2 x 10 6 (16.6) 32
– 600 °F (0 – 315 °C): 9.5 x 10 6 (17.1)
32 – 1000 °F ( 0 – 538 °C): 10.3 x 10 6 (18.5)
32 – 1200 °F (0 – 649 °C): 10.7 x 10 6 (19.3)
32 – 1500 °F (0 – 873 °C): 11.2 x 10 6 (20.2)
Elastic modulus: ksi (MPa)
28 x 103 (193 x 103) when stretched and when twisted
11.2 x 103 (78 x 103)
Magnetic Permeability: H = 200 Oersted: Annealed < 1.02 max
Melting Range: 2500 – 2550 °F (1371 – 1400 °C)
Thermal properties of 321 stainless steel
When it comes to thermal performance, 321 stainless steel excels. Its unique composition gives it excellent high temperature strength and oxidation resistance. This makes it ideal for applications that are constantly exposed to extreme heat.
A key characteristic of 321 stainless steel is its ability to resist scaling at temperatures up to 1600°F (871°C). This means that the material maintains its structural integrity and does not degrade or weaken even at elevated temperatures. This characteristic makes it ideal for use in furnace assemblies, exhaust systems, and other high temperature environments.
Another important thermal property of 321 stainless steel is its low coefficient of thermal expansion. This means that the alloy does not undergo significant dimensional changes when exposed to temperature changes. Therefore, it maintains stability and prevents warping or deformation under different thermal conditions.
In addition, the excellent thermal conductivity of 321 stainless steel allows for efficient heat transfer between materials. This property ensures uniform heating or cooling of the entire structure made from the alloy.
The thermal properties of 321 stainless steel make it an excellent choice for applications requiring high temperature resistance without compromising strength or durability. Its ability to withstand fouling and maintain dimensional stability sets it apart from other alloys in severe thermal environments.
Heat treatment and welding of 321 stainless steel
321 stainless steel can be processed by heat treatment and welding to change its performance and shape. The following is some basic information about heat treatment and welding processing of 321 stainless steel:
Solution Annealing: In the temperature range of 1050°C to 1150°C, heating for a long time, and then cooling rapidly. This process helps eliminate intergranular carbides in stainless steel, improving its corrosion resistance and restoring its tensile strength and toughness.
Stabilization Annealing: Heating at a temperature of 850°C to 950°C, followed by rapid cooling. This process helps to reduce the hardening of 321 stainless steel during welding or other high-temperature processing and maintain its good corrosion resistance.
Select the appropriate welding material: When welding 321 stainless steel, the commonly used welding material is stainless steel wire with similar or similar composition, such as AWS E347-16. This ensures that the weld area has similar properties to the base material.
Control welding temperature: During the welding process, the welding temperature should be controlled to avoid negative effects on the performance of 321 stainless steel. Excessively high welding temperatures may lead to the formation of intergranular carbides, reducing corrosion resistance.
Reasonably design the weld structure: When designing the weld, the shape and size of the weld should be reasonably selected to reduce stress concentration and deformation, and ensure that the weld area has sufficient strength and toughness.
Post-welding heat treatment: After welding, heat treatment such as solution annealing or stabilization annealing can be carried out to eliminate the residual stress generated during the welding process and improve the performance of the weld area.
It is important to note that welding and heat treatment processes should be performed by experienced professionals following proper process specifications and operating guidelines to ensure optimum weld quality and material properties.
321 stainless steel application
321 Stainless Steel is a versatile material that has applications in various industries due to its unique properties. One of the key properties of 321 stainless steel is its excellent corrosion resistance, making it suitable for use in environments that are often exposed to high temperatures and chemicals.
In the aerospace industry, 321 stainless steel is used to manufacture aircraft components such as exhaust systems and engine components. Its ability to withstand extreme temperatures makes it ideal for these applications. In addition, its resistance to oxidation and fouling ensures that these components remain durable even under harsh conditions.
Another important application of 321 stainless steel is in the automotive industry. Due to its heat resistance and low coefficient of thermal expansion, it is commonly used in the manufacture of exhaust manifolds and catalytic converters. This allows these components to effectively handle high operating temperatures without warping or deforming.
The pharmaceutical industry also benefits from the use of 321 stainless steel. Because it does not react with many of the chemicals and substances found in the pharmaceutical process, it is commonly used in equipment for the production and processing of pharmaceuticals. The grade’s corrosion-resistant properties help maintain product purity during the manufacturing process.
Additionally, Type 321 stainless steel has found applications in the food processing industry, especially in equipment that involves handling acidic foods or liquids. Its corrosion-resistant properties ensure that food products are processed without introducing contaminants, thereby ensuring compliance with safety and quality standards.
The wide variety of 321 stainless steel applications underscores its versatility as a material of choice for industries requiring strength, durability, and excellent corrosion resistance under high temperature or chemical exposure.
In conclusion, 321 stainless steel is a versatile and valuable material with a range of favorable properties. Its chemical composition, including added titanium, provides excellent resistance to corrosion and high temperatures. The physical properties of 321 stainless steel make it durable and suitable for a variety of applications across industries.
The unique combination of chemical composition, physical properties such as strength and ductility, and impressive heat resistance make Type 321 stainless steel an excellent choice for many industrial applications. Whether you need a material that can withstand extreme temperatures, or one that resists corrosion in harsh environments, 321 Stainless Steel is the answer!