MAKENEXA304 general fabrication route
Consider 304 for many sheet, plate, tube and machined applications when its corrosion context, strength, fabrication, finish and evidence match the service. Exact variant and condition remain important.
Engineering design resource
304 vs 316 stainless steel: which grade fits your custom parts?
If you are choosing 304 vs 316 stainless, decide from the service environment—not a “316 is always better” rule. 304 is often the balanced fabrication and machining grade; 316 is worth the step up when more demanding corrosion context (including some chloride-related service) justifies the chemistry and evidence. Name the exposure, grade variant and product form, then upload CAD so MakeNexa can review supplier routing.
- CAD nowSTEP or native model under one revision
- DrawingCritical dimensions, finish and notes
- QuantityFirst order and any repeat context
- MaterialGrade, condition or open alternatives
- TimingTarget date or priority window
Ready to quote this part?Upload CAD for a reviewed quote across MakeNexa’s supplier network.
Get a QuoteUse this guide
Start from media and joints, then lock the full grade callout before RFQ
If your question is 304 vs 316 stainless for CNC or fabricated parts, ask which requirement decides: general stainless balance, or a more demanding corrosion and cleaning context. 304 commonly wins for broad sheet, plate, tube and machined use when the environment and finish fit. 316 is shortlisted when the specified media, temperature, crevices or cleaning chemistry justify it—and when welding, surface and records can support that choice. These are selection directions, not service-life certificates.
Write the RFQ so a reviewer cannot accept a blind upgrade or downgrade. Define media, concentration, temperature, stress, cleaning, crevices, mechanical loads, product form, forming, welding, machining, finish, cleanliness and evidence. State exact grade variant and specification, including low-carbon suffixes where required. A 304-to-316 swap can change stock, price, lead time, fabrication behavior and validation without changing the drawing title block alone.
Design priorities
Use 304 or 316 when environment and process fit the exact grade
Compare the released material and final surface in the condition in which the component will actually operate.
316 environment-led route
Consider 316 where the specified environment justifies its chemistry and supporting evidence. Validate media, temperature, stress, cleaning, joints and surface for the complete assembly.
Welded assemblies
Both families can enter welded constructions through suitable routes. Define grade variant, joint, heat input, distortion, cleanup, passivation, final inspection and any procedure or welder evidence.
Machined and finished interfaces
Bores, threads, sealing surfaces and cosmetic faces require grade-specific stock, tools, burr control, roughness, cleaning and surface treatment. Finish does not replace material verification.
Common review gaps
Avoid choosing from stainless family names alone
The environment and final fabrication state can matter more than a simplified grade ranking.
Chloride risk reduced to one word
316 may offer an advantage in some chloride-related environments, but concentration, temperature, wet-dry cycles, stress, crevices and cleaning still require application-specific review.
Grade suffix omitted
Low-carbon and other grade variants may matter for welding, corrosion or specification compliance. Use the full governing callout and required material records.
Passivation treated as repair
Cleaning and passivation cannot correct an unsuitable grade, poor joint, embedded contamination, rough crevice or flawed design. Define the complete material and surface route.
Regulated suitability inferred
Food, medical, marine, pressure or other regulated use depends on project standards, validation, supplier qualifications, surface, cleaning and authorization. A 304 or 316 label does not establish approval.
Practical choices
Choose 304, 316 or a different material route
The decision should state the environment and manufacturing constraints that make one route appropriate.
Select 304
Use exact 304 variant, condition and form when its general corrosion context, fabrication, machining, finish and supply fit. Define evidence and final surface.
Select 316
Use exact 316 variant, condition and form when the service environment and evidence justify it. Control joints, crevices, cleaning, passivation and inspection.
Select another alloy or design
Duplex, precipitation-hardening stainless, nickel alloy, titanium, coated steel, polymer or a redesigned assembly may better fit strength, temperature, corrosion or cost. Revalidate the complete system.
Design decision table
304 and 316 compared on published properties
Typical published values for the annealed condition. Actual values vary with product form, cold work and the supplier's material certification, and the project requirement is confirmed on the reviewed quote rather than from this table.
| Property or decision factor | 304 | 316 |
|---|---|---|
| Tensile yield strength (typical) | 215 MPa / 31 ksi | 205 MPa / 30 ksi |
| Ultimate tensile strength (typical) | 505 MPa / 73 ksi | 515 MPa / 75 ksi |
| Modulus of elasticity | 193 GPa / 28 Msi | 193 GPa / 28 Msi |
| Density | 8.00 g/cm³ | 8.00 g/cm³ |
| Hardness (typical) | About 70 HRB annealed | About 79 HRB annealed |
| Elongation at break (typical) | About 40% | About 40% |
| Principal alloying difference | Roughly 18% chromium and 8% nickel, no molybdenum | Roughly 16 to 18% chromium, 10 to 14% nickel and 2 to 3% molybdenum |
| Pitting resistance number | About 18 to 20 | About 24 to 26 |
| Chloride behaviour | Pits in coastal air, de-icing salt and saline process fluid | Commonly held below about 200 ppm chloride at ambient temperature; resistance still falls as temperature rises |
| Machining behaviour | Work-hardens quickly; needs sharp tooling and a positive feed | Harder at about 79 HRB and the tougher of the two to machine — expect longer cycle and shorter tool life |
| Thermal expansion | About 17.3 µm per metre per °C | About 16.0 µm per metre per °C |
| Low-carbon variant | 304L at 0.03% maximum carbon, about 170 MPa / 25 ksi yield | 316L at 0.03% maximum carbon, about 170 MPa / 25 ksi yield |
| Relative stock cost | Baseline for common bar, sheet and plate | Commonly 1.2 to 1.5 times 304 for equivalent product form |
| Common specifications | ASTM A276 for bar, ASTM A240 for sheet and plate | ASTM A276 for bar, ASTM A240 for sheet and plate |
Turn the guide into an RFQ
304 vs 316 stainless RFQ checklist
Show the exposure and evidence that govern the grade instead of requesting a generic stainless upgrade.
Complete packages move faster: revision-matched CAD, critical dimensions, quantity and material notes are enough to open engineering review across the network.
Get a Quote- 01
Submit the controlled model, drawing, revision and service environment
- 02
State preferred grade variant, condition, product form, specification and alternatives
- 03
Define media, concentration, temperature, stress, cleaning, crevice and maintenance context
- 04
Mark bends, welds, threads, sealing surfaces, contact zones and critical finishes
- 05
Specify roughness, cleanup, passivation, masking, contamination and packaging
- 06
List quantities, material records, supplier qualifications, inspection, tests and validation
Questions before routing
Questions when applying this guide
These answers prepare the request; the reviewed quote controls project-specific commitments.
What is the difference between 304 and 316 stainless steel?
Molybdenum, and almost nothing else that matters. 316 carries 2 to 3% of it; 304 carries none. Mechanically they are near-identical — 215 MPa / 31 ksi yield for 304 against 205 MPa / 30 ksi for 316, the same 193 GPa modulus, the same 8.00 g/cm³ density, about 40% elongation each. What the molybdenum buys is chloride resistance: a pitting resistance number of roughly 24 to 26 against 18 to 20. That is the whole decision.
Is 316 always more corrosion resistant than 304?
In chlorides, yes, and by a margin that matters. In other environments the gap narrows to the point of irrelevance — in dry indoor air or fresh water, both perform well and 304 is the cheaper purchase at commonly 1.2 to 1.5 times less. And 316 is not immune: above about 200 ppm chloride at ambient temperature, and at lower concentrations as temperature rises, it pits too. Crevices under gaskets and fasteners fail first in both grades because the trapped fluid concentrates.
Should I use 304L or 316L for welded parts?
Use the L grade matching the corrosion requirement — 304L for non-chloride service, 316L where chlorides are present. The L designation addresses a different problem from the molybdenum: it caps carbon at 0.03% instead of 0.08% so chromium carbides do not precipitate at grain boundaries when the heat-affected zone dwells between roughly 425 and 815 °C. The cost is about 45 MPa of yield, down to roughly 170 MPa / 25 ksi. Dual-certified 304/304L and 316/316L stock meets both the carbon cap and the higher mechanical minimums, and is often the cheapest route.
Which is better for CNC machining, 304 or 316?
304, moderately. Both work-harden quickly and both punish a dull tool, but 316 is harder at about 79 HRB against 70 HRB and tougher on tooling, so expect a longer cycle and shorter tool life. Neither is a free-machining grade — 304 rates around 45% on that scale against roughly 78% for 303. If machining cost dominates and the part is not exposed to chlorides, 303 is worth comparing; if chlorides are present, pay the 316 machining penalty.
Does passivation make 304 perform like 316?
No. Passivation to ASTM A967 removes free iron embedded by tooling and lets the existing chromium oxide film reform evenly — it restores 304 to its own best behaviour, it does not add molybdenum. The pitting resistance number stays around 18 to 20. If the service is chloride-bearing, passivating 304 does not close the gap to 316 at 24 to 26.
Can I replace 304 with 316 without changing the drawing?
Not by assumption, even though it is the safer direction on corrosion. Yield drops slightly from 215 to 205 MPa, machining cost rises, stock cost rises commonly 1.2 to 1.5 times, and any welded assembly may need the L grade instead. Review strength, cost, availability, weld procedure and finish, then release the chosen grade through controlled change before RFQ routing.
Next step
Send the package and get a reviewed quote
Apply the guide to a real drawing and RFQ package. MakeNexa routes capable suppliers from a global network covering competitor-class process categories, then returns a prepared quote or focused clarification for your revision.