403 vs 316 vs 304 Stainless Steel Fabrication – Which Fits Your Project?

304 Stainless Steel Fabrication is the industry standard for custom metal enclosures. Choosing the right material is the crucial first step in determining product performance, cost, and lifespan.

Drawing on 26 years of practical experience, we will provide you with clear recommendations from three dimensions: chemical composition, corrosion resistance, and processing performance, combined with real-world application scenarios. This will enable you to decide in just five minutes.

304, 316, and 403: Differences and Material Selection Suggestions

1.Material composition type and chemical composition

Bottle type	Organizational type	Cr content	Ni content	Mo content	Magnetic property
304	Austenite	~18-19%	~8-9%	No	Non-magnetic or micro-magnetic
316	Austenite	~18-19%	~10-12%	2-3%	Non-magnetic or micro-magnetic
403	Martensite	~12%	No	No	Magnetic

2. Core performance differences

Corrosion resistance: 316 > 304 > 403.

• 304 can resist atmospheric corrosion as well as moderate levels of oxidation and reduction environments. Still, it is relatively sensitive to pitting in certain situations.
• 316, due to the addition of 2-3% molybdenum, has stronger resistance to salt-containing environments, chemical media, and industrial pollutants. 316 is usually 20-30% more expensive than 304.
• 403’s corrosion resistance is sufficient for most routine applications, but it is generally inferior to the 300 series stainless steel.

Hardness and Heat Treatment:

🔹403 is a type of stainless steel that can be hardened. Its hardness is relatively high after quenching.
🔹304 and 316 belong to austenitic stainless steel. They cannot be hardened through heat treatment, but their strength can be enhanced through cold processing.

Formability and weldability:

The formability of 304 is higher than that of 316, making it easier to shape and weld. The overall weldability of the 300 series austenitic stainless steel is superior to that of the 400 series.

3. Applicable scenarios and material selection suggestions

Application scenario	Recommended Materials	Reasons
General industrial enclosures, chassis and cabinets, food-contact equipment	304	Overall performance is excellent and the cost-effectiveness is the highest.
Marine engineering, chemical processing equipment, medical devices	316	The molybdenum element offers outstanding resistance to chloride corrosion.
Low-cost structural components, heat-resistant parts	403	Low cost, capable of hardening, but with limited corrosion resistance.

Core principle of material selection:

• For most indoor and outdoor general-purpose sheet metal enclosure requirements, 304 stainless steel fabrication is the optimal solution that balances performance and cost.
• If the product will be exposed to humid, salt spray, or chemical corrosion environments for a long time, it should be upgraded to 316.
• If it is only a low-cost, low-corrosion structural component, 403 can be an alternative.

Actual Case

304 stainless steel instrument casing

Last year, a European industrial equipment manufacturer contacted us. They were developing a new type of precision analysis instrument and needed to customize a batch of 304 stainless steel casings.

The customer candidly informed us that their previous suppliers had caused them many problems – frequent delays in delivery, surface treatment flaws, inconsistent dimensions between batches, and frequent rework on the assembly line.

This time, their requirements were very clear: the quality must be excellent, and the delivery date cannot be delayed by even one day.

12% cost savings via engineer optimization

After receiving the drawings, our engineers first reviewed them. They identified three areas for optimization:

• Excessively small bending R-angles reduce production yield.
• Misalignment between welding positions and wire drawing direction eliminates one grinding process.
• Overly tight installation hole tolerances call for slight adjustments.

We invited the client to have an online meeting. The engineers demonstrated the optimization logic one by one using 3D drawings. Eventually, the client fully adopted the optimization plan, saving approximately 12% of the material costs.

Free sample verification, speaking with quality  

The customer had concerns about the quality. We offered them a free sample service. The samples were produced on a dedicated sample production line within 72 hours and sent to the customer.

After receiving the samples, the customer verified them themselves. All material components and dimensions were rechecked and met the standards. The customer then placed a random 200,000-piece order.

Batch delivery and post-sale follow-up

During the production process, the business team synchronizes the progress every week – from the warehousing of raw materials, the first-piece inspection, to the packaging of the finished products- with all information provided in pictures and text.

The quality control team conducts multiple rounds of inspection and sampling to ensure that each item is consistent with the sample. The goods are delivered on time according to the agreed delivery date.

At the beginning of this year, this client placed two additional new project orders and even actively recommended us to their partner in Germany.