Introduction
When it comes to stainless steel, two of the most common grades you’ll encounter are 304 and 430. Both offer good corrosion resistance and durability, but there are some key differences you should know about before choosing one over the other.
In this blog post, we’ll cover five things most people haven’t been told when comparing 304 stainless steel vs 430. We’ll look at differences in composition, corrosion resistance, strength, cost, welding, magnetism, and more. We’ll also overview some basics about each grade.
By the end, you’ll know how to select the best grade for your application. Let’s get started!
Composition Comparison
The first thing to know is that 304 and 430 have different compositions, which account for some of their varying characteristics:
| Alloy | % Cr | % Ni | % C | Other |
|---|---|---|---|---|
| 304 | 18-20 | 8-10.5 | ≤0.08 | Mn: 2.0 Max |
| 430 | 16-18 | – | ≤0.12 | S: ≤0.030 |
As you can see, 304 contains nickel as well as more chromium than 430 stainless steel. 430 lacks nickel and instead includes sulfur.
The higher chromium and nickel content of 304 makes it more resistant to corrosion than 430. Nickel also makes 304 technically an austenitic stainless steel, although 430 can also be austenitic depending on heat treatment.
Corrosion Resistance
When looking at 304 stainless steel vs 430, corrosion resistance is one of the biggest differences. As covered, 304 contains more chromium and nickel, making it more corrosion resistant than 430:
- 304: Highly resistant to a wide range of environments and chemicals. Generally only attacked by acidic solutions containing chlorides or halides. Suitable for applications where corrosion resistance is important but high strength is less critical.
- 430: Has fair corrosion resistance but can rust in harsh environments, especially those containing chlorides. Best used for milder application conditions where high strength is needed but corrosion resistance is secondary.
Essentially, 304 can handle a wider variety of environments, acids, chemicals, salt exposure, etc without rusting or deteriorating. 430 may rust under some exposure conditions due to its lower chromium and nickel content, but offers higher strength.
Strength and Hardness
When looking at strength and hardness, 430 stainless steel generally wins out over 304:
- 430: Higher carbon content increases hardness and provides tensile strengths up to 1825 Mpa after hardening and tempering heat treatments. Used when good corrosion resistance plus high mechanical properties are needed.
- 304: Considered moderately hard, with average Brinell hardness around 200 HB. Tensile strength ranges from 515 to 860 MPa. Selected when corrosion resistance is more important than high strength.
So while 304 is tougher than plain carbon steel, 430 can reach up to double the tensile strength through optimized heat treatment. This allows it to be used in applications like cutlery, hand tools, fasteners, gears, valves and appliances.
Cost Comparison
Another difference is 304 vs 430 stainless steel cost:
- 304: Typically higher cost than 430 since it contains nickel. Market price tends to fluctuate more than 430 as well because it’s price is impacted by nickel pricing.
- 430: More affordable than 304 since it does not contain nickel. Prices tend to be more stable.
Of course, total cost also depends on factors like form purchased and quantity ordered. But in general, 430 will be the less expensive choice, sometimes significantly so.
Welding Behavior
The alloys also vary when it comes to welding:
- 304: Readily weldable using common stainless steel welding methods. Possesses good ductility to withstand thermal stresses from welding without compromising corrosion resistance or joint quality.
- 430: Considered unweldable by conventional fusion welding. Can lose corrosion resistance and become brittle around heat-affected zones when welded. Special welding filler material needed. Brazing is a better option.
304’s welded characteristics lend well to applications where hygiene is important or future modifications may be required. This includes systems piping and tanks in food processing plants, chemical works, degreasing equipment, etc.
Magnetic Permeability
The alloys also have notably different magnetic properties:
| Alloy | Mag Permeability | Magnetism |
|---|---|---|
| 304 | Very low | Non-magnetic |
| 430 | Low | Ferromagnetic |
304 is non-magnetic in all conditions and temperatures, allowing it to be used where no additive magnetic fields are desired.
430 is considered ferromagnetic, meaning it’s magnetic properties can be controlled through mechanical and thermal treatments. Applications include magnetic assemblies and transformer cores.
So 430 can find uses based on its magnetism, while 304 is ideal for non-mag applications.
Conclusion：304 Stainless Steel vs 430
While 304 and 430 stainless steel have some similarities, they have very different characteristics that make each suited to particular applications where their strengths play best according to the intended service conditions and cost considerations.
Knowing specifics like corrosion resistance, mechanical properties, weldability, and magnetism allows your to select the best grade to fit performance requirements and budget for your project. Speaking to manufacturers can also help determine which is tailored better to your particular needs.
With the basics covered in this post, you hopefully now have the knowledge to choose the right stainless steel next time you’re comparing 304 vs 430!
FAQ
Still have some lingering questions on differences between 430 and 304 stainless steel? Here are answers to some common queries:
Does 304 or 430 stainless steel rust?
- 304 has high corrosion resistance and does not rust easily except under extended acidic exposure. 430 can rust under harsh conditions or chlorides/acids unless passivated.
Can 430 be welded?
- While possible for light welds, 430 is generally considered unweldable compared to 304. It requires special precautions and loses corrosion resistance when welded.
Is 430 magnetic?
- Yes, 430 stainless steel is ferromagnetic and can be magnetized/demagnetized through mechanical and heat treatments. 304 is non-magnetic under all conditions.
Which is stronger – 304 or 430 SS?
- 430 has higher hardness and tensile strength, especially when heat treated. 304 is moderately hard but valued more for corrosion resistance.
Which stainless is cheaper, 304 or 430?
- 430 stainless almost always carries lower market pricing than 304 since it contains no nickel. Actual prices vary based on form, distributors, etc.