As a professional custom stainless steel investment casting foundry, Pingheng Machinery has been dedicated to the field of 304 and 316 stainless steel casting for many years. With extensive experience, we can offer perfect solutions for your stainless steel casting project.
304 and 316 stainless steel, as the two most common stainless steel materials, are difficult to distinguish visually. However, as industrial casting materials, their differing chemical compositions result in significant distinctions. Selecting the appropriate material based on your product’s intended application can result in substantial cost savings throughout the service life of your castings. Whether you’re seeking the right casting material for your product or just want to have a deeper understanding of 304 and 316 stainless steel, this article is perfectly suited for you.
What Type of Alloy is Stainless Steel
In general, stainless steel is an iron-based alloy. The chromium element can form an oxidized layer on the surface, which can isolate the material from a corrosive medium, making the material “stainless”. This layer is self-repairing, regenerating spontaneously in the presence of oxygen when damaged. Generally speaking, the higher the content of chromium, the better the self-repairing properties of the steel. Both 304 stainless steel and 316 stainless steel belong to the austenitic stainless steel. Austenitic stainless steel is considered the most widely used type of stainless steel globally.
304 Stainless Steel
304 stainless steel is the most commonly used stainless steel in the world, which is also called 18/8 stainless steel, as its main composition is 18% chromium and 8% nickel. It maintains an excellent balance between its properties and production costs, offering exceptional value for money.
316 Stainless Steel
316 stainless steel has a higher content of chromium and nickel enhances its performance in harsh environments, making it widely used in industrial environments with strong corrosive conditions.
304 vs 316 Stainless Steel Composition
| 304 | 316 | |
| Carbon | ≤0.08 | ≤0.08 |
| Manganese | ≤2.00 | ≤2.00 |
| Phosphorus | ≤0.045 | ≤0.045 |
| Sulfur | ≤0.030 | ≤0.030 |
| Silicon | ≤1.00 | ≤1.00 |
| Chromium | 18.00 – 20.00 | 16.00 – 18.00 |
| Nickel | 8.00 – 10.5 | 10.00 – 14.00 |
| Nitrogen | 0.10 | 0.10 |
| Molybdenum | – | 2.00 – 3.00 |
| Iron | Bal. | Bal |
Pros and Cons of 304 and 316 Stainless Steel
304 Stainless Steel
Pros
- Corrosion resistance: 304 stainless steel has relatively good corrosion resistance.
- Versatility: Although none of its features are outstanding, the 304 stainless steel composition can be allocated, given its versatility, enabling its application in most industries.
- Durability: Good chemical and mechanical properties make 304 stainless steel with long service time.
- Heat resistance: 304 stainless steel can retain good resistance to high temperatures.
- Weldability: 304 stainless steel is highly weldable within a certain temperature range and is one of the easiest-to-weld stainless steels.
- Formability: 304 stainless steel’s exceptional ductility and uniform deformation characteristics ensure consistent formability.
- Cost-effective: Compared to 316 stainless steel, while its performance is slightly inferior in various aspects, it remains sufficient for routine applications, as well as the lower price.
- Hardness: 304 stainless steel has decent hardness. While it doesn’t match 316 stainless steel, it’s still sufficient for most applications.
Cons
- Unable to withstand strong acid
- Weld sensitization at high temperature
- Weakened strength at high temperatures(925℃ Max)
316 Stainless Steel
Pros
- Superior corrosion resistance: 316 stainless steel offers superior resistance to pitting and crevice corrosion compared to other stainless steels.
- Excellent Durability: Excellent chemical and mechanical properties elevate the durability of 316 stainless steel
- Weldability: Although 316 stainless steel has good weldability, 316L is more suitable for large-scale welding.
- Outstanding heat resistance: The creep resistance of 316 stainless steel enables its casting’s stable performance under high temperatures.
- Non-reactive quality: 316 stainless steel is a non-reactive alloy. Its stable passivation film protects it from reacting with chemicals and pharmaceuticals.
- Hardness: The yield strength and tensile strength of 316 are both superior to those of 304.
Cons
- Higher price
- Less malleable with the addition of molybdenum
- Weld sensitization at higher temperatures
Comparison
| Property | 304 Stainless Steel | 316 Stainless Steel |
| Corrosive resistance | Adequate | Outstanding |
| Hardness | Good | Excellent |
| Durability | Excellent | Good |
| Weldability | Adequate | Adequate |
| Formability | Excellent | Good |
| Machinability | Fair | Inferior |
| Heat resistance | Good | Excellent |
| Price | Cost-effective | Expensive |
304 vs 316 Stainless Steel Properties
Physical Properties
| 304 Stainless Steel | 316 Stainless Steel | |
| Appearance | Metallic Silver | Metallic Silver |
| Density | 7.93 – 7.94 g/cm³ | 7.99 – 8.00 g/cm³ |
| Magnetic | Non-magnetic | Non-magnetic |
| Thermal Conductivity | 16.2 – 16.3 W/m.K | 15 – 16 W/m·K |
| Electrical Resistivity | 0.73 μΩ·m (20°C) | 0.74 μΩ·m (20°C) |
| Melting Point | 1399 – 1420 °C | 1375 – 1400 °C |
Chemical Properties
| 304 Stainless Steel | 316 Stainless Steel | |
| Corrosion Resistance | Adequate | Outstanding |
| Hygiene and Cleanability | Excellent | Excellent |
| Durability | Excellent | Good |
| Oxidation Resistance | Good | Outstanding |
Mechanical Properties
| 304 Stainless Steel | 316 Stainless Steel | |
| Hardness (Brinell HB) | 201 Max | 217 Max |
| Yield Strength | 205 MPa | 205 MPa (annealed), up to 310 MPa (cold finished) |
| Tensile Strength | 515 MPa | 515 MPa (annealed), up to 620 MPa (cold finished) |
| Elongation (% in 50mm) | 70% | 50% |
| Modulus of Elasticity | 193-200 GPa | 193 GPa |
Processing Properties
| 304 Stainless Steel | 316 Stainless Steel | |
| Weldability | Adequate | Adequate |
| Formability | Excellent | Good |
| Machinability (annealed) | Fair | Inferior |
304 vs 316 Stainless Steel Application
After the basic understanding of 304 and 316 stainless steel’s properties, it’s time to have an insight into the application of the two most widely used stainless steels, which could help you choose the proper material for your casting project.
The application of 304 stainless steel is in every corner of our lives. It’s mainly applied to appliances (refrigerators and washing machines), heat changers, stainless steel panels, automotive trim and accessories (door handles, windshield wipers, etc.), chemical pipelines, kitchen hardware, and non-critical aerospace components.
The application of 316 stainless steel is rather industrial in contrast. From marine applications to chemical processing, medical and pharmaceutical manufacturing to aerospace, food industry to automotive production, 316 stainless steel is utilized in medical device fabrication, nuclear power plant systems, aerospace engines, marine components (steel cables, ship ladders, etc.), pharmaceutical equipment, food processing machinery, and chemical and petroleum production/processing equipment and accessories (valves, pump housings, etc.).
How to Identify Stainless Steel Grades
There are many ways for stainless steel identification. If you cooperate with us, the test report could be directly given to you. However, if there are some personal needs, the best way to identify 304 and 316 stainless steel is a chemical spot test. There is no molybdenum in 304 stainless steel. Therefore, when a specific chemical reagent (typically acidic) is applied to the stainless steel surface, 304 stainless steel will not react (there is no molybdenum in it), and 316 stainless steel will react with the reagent (there is molybdenum in it) inversely. Commonly, there are red or pink spots on the surface, which can be identified as 304 and 316 stainless steel.
The Price of 304 Stainless Steel and 316 Stainless Steel
304 stainless steel is cheaper than 316 stainless steel. The chemical elements of chromium and nickel are the key points affecting the price between 304 and 316. Since the lower chemical composition of chromium and nickel, its price of 304 is lower than that of 316 as well.
Is It Worth the Extra Cost?
It largely depends on the application of your castings. When working in environments with high chemical exposure, 316 stainless steel is worth the extra investment. Although the initial cost is higher, it offers a longer service life.
Choosing the Right Stainless Steel for Your Application
After browsing all this information about 304 and 316 stainless steel, here comes the most important question: How to choose the right one for your casting project? To be honest, there are many factors you should take into consideration, including the cost, properties of the material, and other aspects. If your castings are intended for use in mildly corrosive chemical environments, such as kitchenware or everyday household items, cost-effective 304 stainless steel will fully meet your requirements. However, in harsher environments, 316 stainless steel is still your best choice. All in all, 304 stainless steel is a good answer if there are no extra requirements. However, when it comes to long-term operation in a demanding environment, it is time to turn to 316 stainless steel.
Future Trends in Stainless Steel Use in Manufacturing
In recent years, China’s stainless steel production has been steadily increasing, maintaining a leading position in the global supply market. Stainless steel grade 300 series accounts for more than fifty percent of the total, with its applications expanding from construction, automotive, and home appliances to aerospace, medical, and other fields.
Stainless steel is a recyclable material with distinctive strengths in environmental protection and sustainable development. With the rise of global awareness of environmental protection, stainless steel is replacing the traditional materials used in construction, automotive, appliances, and other fields. In the future, stainless steel will transition toward sustainable manufacturing and advance into new high-end sectors.
In a word, the application of stainless steel manufacturing is evolving toward high-end, green, and intelligent directions. Its application and connotation are continuously deepening and expanding.
Conclusion
After learning the above information, there must be a general answer to choose for your stainless steel casting project. If you still have doubts about the material choice, don’t worry, Pingheng Machinery is here for you.
Pingheng Machinery has been dedicated to investment casting for over 20 years, specializing in casting stainless steel components. With extensive casting experience, a professional technology team, and a stringent quality control system, you can trust our casting quality wholeheartedly.
With a 9,000-square-meter factory and an annual casting capacity of 2,400 tons, Pingheng Machinery can handle orders of any volume. Our custom casting service provides you with a one-stop solution for your stainless steel casting project.
Besides, Pingheng Machinery specializes particularly in casting components with airtightness requirements. Welcome to contact us for your next stainless steel casting project anytime.
