Stainless Steel 304
Stainless steel 304 is a widely used austenitic stainless steel known for its good corrosion resistance, ductility, ease of fabrication, and moderately high strength.
Chemical Composition of Stainless Steel 304
Stainless steel 304 is distinguished from other grades by its balanced composition, offering a unique blend of corrosion resistance, formability, and versatility.
Characterized by a higher chromium (18-20%) and nickel (8-12%) content, it provides exceptional resistance to a wide range of chemicals and atmospheric environments.
Its low carbon content (maximum 0.08%) enhances its corrosion resistance while maintaining its strength. This non-magnetic alloy is also notable for its excellent weldability and formability, making it ideal for various applications, from kitchen utensils to chemical equipment.
These attributes make 304 stainless steel a preferred choice in both industrial and domestic settings.
| Chemical Composition | Proportions | Role of Each Element |
|---|---|---|
| Iron (Fe) | Balance | Iron is the base metal that makes up the majority of 304 stainless steel. |
| Chromium (Cr) | 18-20% | Chromium is the most important alloying element in 304 stainless steel. It provides corrosion and oxidation resistance. |
| Nickel (Ni) | 8-10.5% | Nickel enhances corrosion resistance, improves hardness and strength at high temperatures, and improves low temperature impact toughness. |
| Manganese (Mn) | 2% max | Manganese improves hot working characteristics like machinability and ductility. |
| Silicon (Si) | Max 0.5% | An impurity that decreases ductility and fracture toughness. Kept to a minimum. |
| Silicon | 1% max | Silicon increases corrosion and oxidation resistance. |
| Carbon (C) | 0.08% max | Carbon increases the strength of the steel, but higher levels can reduce its corrosion resistance, which is why it's kept low in 304 stainless steel. |
| Nitrogen (N) | 0.1% max | Nitrogen improves yield and tensile strength. |
Note: Stainless steel 304 composition and properties vary slightly by producer; contact us for specifics.
General Characteristics of Stainless Steel 304
Stainless steel 304 is corrosion-resistant, durable, non-magnetic, easily formable, and weldable, ideal for various industrial and domestic applications.
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Physical properties
| Density | 8.0 g/cm3 |
| Corrosion resistance | Excellent in a wide range of environments |
| Melting Point | Around 1400-1450°C. |
| Magnetism | Non-magnetic |
| Coefficient of Thermal Expansion | 17.2 x 10-6/°C at 100°C |
| Thermal Conductivity | 16.2 W/m-K at 100°C |
| Electrical properties | 72 μΩ-cm at 20°C |
Mechanical properties
| Ultimate Tensile Strength (UTS) | Typically around 505-690 MPa. |
| Yield Strength (0.2% Offset) | 205-310 MPa |
| Elongation at break | 40-60% |
| Modulus of Elasticity (Elastic Modulus) | 190-210 GPa |
| Fatigue Strength | around 240 MPa |
| Brinell Hardness | >= 187HB |
| Vickers hardness | under 200HV |
Available Surface Finishing
| Polishing | Mirror-like reflective finish achieved by progressive polishing with abrasives. Different grit sizes can produce various levels of polish. |
| Bead blasted | Textured matte finish from impact of glass or ceramic beads at high pressure. Provides uniform fine roughness. |
| Electroplating | Smooth polished finish with high luster and reflectivity, done by electrochemical dissolution. |
| PVD coatings | Thin ceramic coatings like titanium nitride applied by vapor deposition methods. Provide wear resistance and color. |
Note: The properties of Stainless Steel 304 can exhibit minor variations depending on the supplier.
Types of CNC Machining Stainless Steel Process
AT-Machining employs various stainless steel machining services to produce high-quality components in diverse shapes and sizes. Our capabilities include CNC milling, turning, Swiss machining, EDM, and grinding.
By combining these techniques, our skilled engineers craft efficient manufacturing solutions tailored to each project’s specifications.
With a focus on precision and accuracy from start to finish, AT-Machining consistently meets both our own rigorous standards and our customers’ expectations.
Comparing Different Grades of Stainless Steel Simplified
|
Grade of Stainless Steel
|
Advantages
|
Disadvantages
|
Main Applications
|
Machinability
|
|---|---|---|---|---|
|
SS 304
|
Highly versatile, widely used, good strength and corrosion resistance.
|
Less resistant to chlorides
|
Kitchen equipment, architectural paneling, chemical containers
|
Excellent
|
|
SS 304L
|
More resistant to carbide precipitation during welding
|
Lower strength compared to 304.
|
Heavy welded components, chemical processing equipment.
|
Excellent
|
|
SS 316
|
Superior corrosion resistance, particularly against chlorides and acids.
|
More expensive than 304
|
Marine environments, chemical processing, pharmaceutical equipment.
|
Good
|
|
SS 316L
|
Superior weldability, resistant to pitting and crevice corrosion.
|
More costly than 316.
|
Heavy gauge welded components, chemical processing equipment.
|
Good
|
|
SS 17-4 PH
|
Excellent mechanical properties, can be heat treated for higher hardness.
|
Susceptible to stress corrosion cracking without final PH temper
|
high strength parts
|
Good
|
|
SS 416
|
High strength and hardness, low cost
|
Poor corrosion resistance, brittle
|
Gears, shafts, valves, bearings
|
Fair
|
Stainless Steel 304 & 304L
Stainless Steel 304 and 304L are similar, both part of the austenitic family of stainless steel, yet they have key differences, primarily in their carbon content. Stainless Steel 304, the most common form of stainless steel used around the world, has a maximum carbon content of 0.08%. This composition provides a good balance of strength, corrosion resistance, and weldability.
In contrast, Stainless Steel 304L (the “L” stands for “Low carbon”) contains a lower carbon content, capped at 0.03%. This reduction in carbon improves the material’s weldability and minimizes the risk of corrosion that can occur in welded areas, especially in high-corrosion environments. This makes 304L a better choice for applications requiring extensive welding or use in corrosive environments. However, the difference in carbon content slightly reduces the strength of 304L compared to 304.
Common Applications of Stainless Steel 304
The key drivers for using CNC machined 304 stainless steel are corrosion resistance, ease of cleaning, high strength, excellent formability, and the ability to achieve fine surface finishes. Industries value these attributes to ensure safety, hygiene, and long functional lifespans for stainless steel components.
Medical Devices
CNC machining of Stainless Steel 304 is crucial in medical applications due to its excellent corrosion resistance and hygienic properties. It's used for surgical instruments, implants, and equipment that require strict sanitation and durability.
Food Processing Equipment
The non-reactive nature of Stainless Steel 304 makes it ideal for food processing equipment. CNC machining ensures precise components for mixers, grinders, and conveyors, maintaining food safety standards and resisting corrosion from acids and cleaning chemicals.
Automotive Parts
In the automotive industry, CNC machined Stainless Steel 304 parts are valued for their strength and corrosion resistance. Components like exhaust systems, grilles, and trim benefit from 304’s durability and resistance to extreme temperatures and environmental conditions.
FAQS About Stainless Steel 304
The primary challenges include its tendency to work harden and the need for sharp cutting tools. SS304 can quickly harden during machining, which requires slower cutting speeds and more frequent tool changes to maintain precision and avoid tool wear.
Yes, SS304 can be used for precision parts. However, it requires careful control of machining parameters to maintain accuracy and surface finish, given its work hardening properties.
Yes, coolant is necessary when machining SS304. It reduces the cutting temperature, thereby minimizing work hardening and tool wear. Water-based coolants are commonly used, but the specific type may vary based on the machining process and workshop preferences.
Post-machining treatments for SS304 parts can include stress relieving, especially for complex or tightly toleranced components, and surface treatments like passivation to enhance corrosion resistance. Polishing or brushing can also be applied to improve surface aesthetics.
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