Material Guide & Selection
Stainless Steel Properties: Grades, Charts & How to Choose
Stainless steel properties come down to one ingredient: chromium. Any steel with at least 10.5% chromium forms a thin, self-healing oxide layer on its surface, and that invisible layer is what makes stainless steel resist rust. Everything else, from strength to magnetism to cost, depends on the grade you choose.
This guide covers the main stainless steel grades, their mechanical properties, and how to pick the right one for your application. It is written by the engineers at Baetro who machine and fabricate stainless steel every day, so it goes beyond the data sheet. You will learn not just what each grade is, but how it machines, forms, and finishes, and which one actually fits your part.
10.5% Cr
Minimum chromium content
150+ Grades
Across 5 main families
Self-healing
Oxide layer protection
Engineer-written
Machining & fabrication focus
Material Fundamentals
What Is Stainless Steel?
Stainless steel is a family of iron-based alloys defined by a minimum of 10.5% chromium. When chromium meets oxygen, it forms a passive chromium-oxide layer only a few atoms thick. That layer blocks moisture and oxygen from reaching the iron underneath, so the steel does not rust the way plain carbon steel does. If the surface gets scratched, the layer reforms on its own, as long as oxygen is present.
Grades add other elements to tune specific properties. Nickel improves toughness and corrosion resistance. Molybdenum boosts resistance to chlorides and pitting. Carbon raises hardness and strength. This is why the different types of stainless steel behave so differently, and why grade selection matters more than the "stainless" label alone.
Minimum 10.5% Chromium
The threshold that defines stainless steel
Self-Healing Oxide Layer
Reforms automatically when scratched
Alloying Elements
Nickel, molybdenum, carbon tune properties
Grade Selection Matters
Different grades behave differently in fabrication
Passive Layer Protection
The invisible chromium-oxide layer that gives stainless steel its corrosion resistance.
Fabrication guide
Machinability, Weldability and Formability
When you compare stainless steel properties on a data sheet, you learn what a grade is. You rarely learn how it behaves in the shop. This is where a manufacturer's perspective helps.
Machining
Machinability
Austenitic grades like 304 and 316 work-harden as you cut them, so they need sharp tooling, rigid setups, and proper feeds to avoid a glazed surface.
- Free-machining variants: 303 cuts more easily but sacrifices some corrosion resistance
- Martensitic grades: 410 machines harder than austenitic grades
- Key requirement: sharp tooling and rigid setups to prevent work hardening
- Best practice: proper feeds and speeds to avoid glazed surfaces
Welding
Weldability
Austenitic grades weld well, and the low-carbon L grades (304L, 316L) reduce the risk of weld decay on heavy sections.
- Austenitic: 304 and 316 weld well with proper technique
- Low-carbon L grades: 304L and 316L reduce weld decay risk on heavy sections
- Martensitic: 410 needs preheat and post-weld heat treatment to avoid cracking
- Duplex: 2205 requires careful heat input control
Forming & finishing
Formability & Finishing
Austenitic stainless bends and forms cleanly, making 304 the go-to for sheet metal enclosures and brackets. Stainless takes passivation well to restore the protective oxide layer after machining.
- Formability: 304 is the easiest to bend and form for sheet metal work
- Ferritic 430: less formable than austenitic grades
- Martensitic: forms poorly, best suited for machined parts
- Passivation: restores the oxide layer after machining
- Other finishes: electropolishing and bead blasting for clean, uniform surfaces
Procurement confidence
Why Choose Baetro for This Stainless Steel Guide
Engineers and procurement managers trust this guide because it is written by the people who machine, form, and finish stainless steel every day — not a marketer rewriting a data sheet.
Engineer-Written, Not Marketing
This guide comes from the Baetro engineering team, the same people who quote, machine, and inspect stainless steel parts. No fluff, no recycled content — just practical information you can actually use.
Data You Can Trust
All property data is sourced directly from ASTM A240 and industry-recognized references like Rolled Alloys, not from generic online tables. You get the same numbers we use for quoting and process planning.
Beyond the Data Sheet
We tell you what the data sheet does not: how each grade machines, welds, forms, and finishes. That is the layer that separates a successful part from a headache, and it is the value we add.
Grade Comparison Made Simple
We cut through the confusion by grouping grades by family and application. You learn which grades are similar, which are different, and where those differences actually matter for your part.
Fabrication-Focused Guidance
Knowing the tensile strength is useful. Knowing how the steel behaves on a press brake, a welding table, or a CNC lathe is what gets parts made correctly. We include that perspective in every section.
Free DFM Review for Your Application
Reading a guide is one thing. Applying it to your specific part is another. Upload your CAD file and our engineers will recommend the right grade, review your design, and quote the part — all in under 60 seconds.
Material library
Materials We Mill
We machine 50+ materials across metals and plastics, with full material certifications and traceability available for every project.
Metals
Aluminum Alloys: 6061-T6 general-purpose, excellent machinability, weldable; 7075-T6 high-strength aerospace-grade; 2024-T3 high fatigue resistance; 5052 corrosion-resistant and marine applications.
Learn more about aluminum CNC machining
Stainless Steel: 304 general-purpose, corrosion-resistant, food-grade; 316 marine-grade, chemical-resistant, medical applications; 17-4 PH precipitation-hardened, high strength with corrosion resistance; 303 free-machining grade for faster production.
Learn more about stainless steel CNC machining
Other Metals: Carbon steel (1018, 1045, 4140), Brass (C360), Titanium (Grade 2, 5), Copper (C110), Tool steel (O1, A2, D2).
Plastics
PEEK: High-temperature, medical-grade, chemical-resistant polymer.
Learn more about PEEK CNC machining
ABS: Impact-resistant, cost-effective prototyping material.
Nylon (PA6, PA66): Wear-resistant, low friction, suitable for bearings and bushings.
POM (Delrin/Acetal): Excellent dimensional stability for precision mechanical parts.
Polycarbonate: Transparent, high-impact strength.
Acrylic (PMMA): Optical clarity, decorative applications.
Material
Stainless Steel
304, 316, 17-4 PH, and 303 grades for corrosion resistance and high strength applications.
Material
Titanium
Grade 2 and 5 for aerospace and medical applications requiring high strength-to-weight ratios.
Material
PEEK
High-performance plastic for demanding thermal, chemical, and biocompatible applications.
Material reference
Stainless Steel Properties by Grade
Here are the stainless steel grades engineers spec most often, with what each is best for.
| Grade | Family | Key Trait | Typical Uses |
|---|---|---|---|
| 304 | Austenitic | General purpose, formable | Food equipment, enclosures, kitchen, tanks |
| 304L | Austenitic | Low carbon, better welding | Welded structures, heavy-gauge fabrication |
| 316 | Austenitic | Molybdenum for chloride resistance | Marine, chemical, medical, coastal |
| 316L | Austenitic | Low-carbon 316 | Welded medical and marine parts |
| 410 | Martensitic | Hardenable, magnetic | Blades, shafts, fasteners, wear parts |
| 430 | Ferritic | Magnetic, low cost | Appliances, trim, indoor decorative |
| 2205 | Duplex | High strength + chloride resistance | Chemical, offshore, pressure vessels |
The "L" grades simply have lower carbon, which reduces the risk of sensitization and weld decay during welding. If your part is heavily welded, the L variant is usually the safer call.
Engineering data
Mechanical Properties of Stainless Steel
Mechanical properties vary widely by grade and by whether the material is annealed or hardened. The table below gives typical annealed values for common grades, based on ASTM A240 data.
Typical Annealed Properties
| Grade | Tensile Strength | Yield Strength | Hardness (max) |
|---|---|---|---|
| 304 | ~515 MPa (75 ksi) | ~205 MPa (30 ksi) | 92 HRB |
| 316 | ~515 MPa (75 ksi) | ~205 MPa (30 ksi) | 95 HRB |
| 410 (annealed) | ~450 MPa (65 ksi) | ~205 MPa (30 ksi) | 96 HRB |
| 430 | ~450 MPa (65 ksi) | ~205 MPa (30 ksi) | 89 HRB |
| 2205 | ~620 MPa (90 ksi) | ~450 MPa (65 ksi) | 31 HRC |
Two things stand out. First, 304 and 316 have nearly identical strength, so you choose between them on corrosion, not strength. Second, martensitic and duplex grades offer much higher strength, but trade away some corrosion resistance or formability to get it.
How to Choose
- 304 / 316: choose 304 for general-purpose applications; choose 316 when chloride exposure, marine environments, or chemical contact demands molybdenum.
- 410 (martensitic): choose when you need hardness, wear resistance, and magnetic response, but accept lower corrosion resistance than austenitic grades.
- 430 (ferritic): choose for low-cost, magnetic, indoor applications where aesthetics and mild corrosion resistance are sufficient.
- 2205 (duplex): choose when you need high strength and excellent chloride resistance, but be aware it is harder to machine and form than austenitic grades.
- Cost impact: 304 is the most affordable; 316 and 2205 add cost for enhanced corrosion or strength.
Grade comparison
304 vs 316 Stainless Steel: Which Is Right?
This is the most common grade question we get, and the answer hinges on one element: molybdenum. Grade 316 adds 2 to 3% molybdenum, which sharply improves resistance to chlorides and pitting corrosion. Grade 304 has none. That single difference drives most real-world decisions.
Choose 304 for General & Indoor Use
Choose 304 when the part lives indoors or in mild environments, when budget matters, and when you need excellent formability.
- Default for food equipment, enclosures, kitchen hardware, and general fabrication
- Excellent formability for sheet metal and bending operations
- Most affordable austenitic stainless steel grade
- Produced daily through our 304 stainless steel machining service
- Ideal for indoor and mild environment applications
Choose 316 for Chlorides & Aggressive Environments
Choose 316 when the part faces chlorides, saltwater, de-icing salts, or aggressive chemicals. Marine hardware, coastal structures, chemical processing, and many medical devices justify the upgrade.
- Marine hardware, coastal structures, and offshore equipment
- Chemical processing and pharmaceutical applications
- Medical devices where chloride exposure is a concern
- Produced regularly through our 316 stainless steel machining service
- Molybdenum addition provides superior pitting resistance
The Bottom Line:
In terms of strength and machinability, the two are nearly the same, so you are really paying for corrosion insurance. If the environment is not chloride-rich, 304 is usually the smarter buy.
Applications
Applications by Grade
The range of stainless steel properties shows up wherever corrosion, hygiene, or appearance matters. Here are common uses by grade.
Grade 304
Food Processing & General Fabrication
Food processing equipment, kitchen hardware, enclosures, tanks, and general fabrication where corrosion resistance and formability are required.
Grade 316
Marine & Medical
Marine fittings, chemical tanks, coastal structures, surgical instruments, and medical devices where chloride resistance and biocompatibility are critical.
Grade 410
Cutlery & Wear Components
Cutlery, valve parts, shafts, and wear components that need hardness and wear resistance, with lower corrosion requirements than austenitic grades.
Grade 430
Appliance Panels & Automotive Trim
Appliance panels, automotive trim, and indoor decorative parts where good corrosion resistance and low cost are sufficient for interior use.
Grade 2205
Chemical Processing & Offshore
Chemical processing equipment, offshore platforms, pressure vessels, and heat exchangers where high strength and chloride resistance are both required.
Cross-industry
Food, Medical, Marine & Energy
Industries span food and beverage, medical, marine, chemical, architecture, and energy. In nearly all of them, the choice between 304 and 316 comes down to the environment — 316 for chloride exposure, 304 for general use.
Material selection
How to Choose a Stainless Steel Grade
Picking a grade gets simpler when you ask three questions in order.
What Environment Will It Face?
This is the biggest factor in grade selection.
- Indoors and mild conditions: point to 304
- Chlorides, salt, or chemicals: point to 316 or a duplex grade
- Marine exposure: 316 or 2205 for chloride resistance
- Food and medical: 304 for general use, 316 for aggressive settings
- Cost impact: 304 is the most affordable; 316 and duplex add cost for enhanced protection
What Mechanical Demands Does It Have?
Choose the grade family that matches your strength and formability needs.
- High strength or hardness: martensitic (410) or duplex (2205)
- Formability matters most: stay austenitic (304, 316)
- Wear resistance: 410 for hardness and abrasion
- High strength + corrosion: 2205 duplex for combined performance
How Will It Be Made?
Fabrication method often decides which variant of a grade to choose.
- Heavy welding: favors the L grades (304L, 316L) to avoid weld decay
- Sheet forming: favors 304 for its excellent formability
- Machined parts in harsh settings: favor 316 for corrosion resistance
- Free-machining needs: 303 cuts more easily but sacrifices some corrosion resistance
How it works
Getting Stainless Steel Parts Made
Understanding stainless steel properties is the first step. Turning the material into a finished part is the next, and that is where we come in.
Upload Your CAD File
Send your design in STEP, IGES, SolidWorks, or Parasolid format. Include your material preference or let us recommend the right grade for your application.
Engineering Review & Material Selection
Our engineers review your design and recommend the stainless steel grade that fits your environment and fabrication needs — 304, 316, 410, or another option.
Make and Fabricate
We machine or fabricate your stainless steel part under one roof, with the same quality system and full material traceability from mill to finished component.
Production Inspection
Parts are inspected at critical stages with dimensional checks to catch deviations early. Stainless steel requires attention to work hardening, so process control matters.
Passivation & Finishing
We passivate stainless steel parts in-house to restore the chromium-oxide layer after machining, ensuring full corrosion resistance. Additional finishes available on request.
Final Inspection & Shipment
Every part receives CMM inspection and final quality review. Parts ship with inspection reports, material certifications, and full traceability — all backed by our ISO 9001 and AS9100 certified quality systems.
Cost considerations
Stainless Steel Cost Factors
Understanding what drives stainless steel part costs helps you choose the right grade for your budget and performance requirements.
- Grade Selection: 304 is the most affordable austenitic grade; 316 adds 20–40% cost due to molybdenum; duplex 2205 is premium but offers higher strength.
- Part Complexity: Deep pockets, thin walls, and tight tolerances increase machining time and cost — especially on work-hardening grades.
- Machinability: 303 is free-machining but costs slightly more than 304; 316 and 410 machine slower, increasing labor cost.
- Forming & Fabrication: Austenitic grades bend and form cleanly; martensitic grades require more care and post-treatment, adding cost.
- Order Quantity: Low volumes have higher per-part cost due to setup; high volumes reduce per-part cost through process optimization.
- Lead Time: Standard 3–7 day lead times included; expedited delivery adds cost for priority scheduling and inspection.
FAQ
Frequently Asked Questions
Answers to common questions about stainless steel grades, properties, corrosion resistance, and material selection.
What are the properties of stainless steel?
Stainless steel is defined by corrosion resistance from at least 10.5% chromium, which forms a self-healing oxide layer. Beyond that, properties vary by grade. Most offer good strength, toughness, and formability, with austenitic grades like 304 and 316 prized for corrosion resistance and martensitic grades like 410 for hardness.
What is the difference between 304 and 316 stainless steel?
Grade 316 adds 2 to 3% molybdenum, which improves resistance to chlorides and pitting corrosion. Grade 304 lacks it. Strength and machinability are nearly identical, so the choice is about environment. Use 316 for marine, chemical, or coastal exposure and 304 for general and indoor use.
Is stainless steel magnetic?
It depends on the family. Austenitic grades like 304 and 316 are generally non-magnetic. Ferritic (430) and martensitic (410) grades are magnetic. Cold working can make even austenitic grades slightly magnetic, so magnetism alone is not a reliable grade test.
Does stainless steel rust?
Stainless steel resists rust far better than carbon steel, but it is not rust-proof. In chlorides, low-oxygen crevices, or when the passive layer is damaged and cannot reform, it can corrode. Choosing the right grade, such as 316 for chloride exposure, and passivating after machining keeps it protected.
Which stainless steel grade is best for food or medical use?
Grade 304 is the standard for food equipment because it is corrosion resistant, easy to clean, and formable. For medical devices and more aggressive or chloride-rich settings, 316 and 316L are preferred for their added corrosion resistance and biocompatibility.
What are the four types of stainless steel?
The four families are austenitic (304, 316), ferritic (430), martensitic (410), and duplex (2205). They differ in crystal structure, which drives differences in magnetism, hardenability, corrosion resistance, and formability.
Material selection guide
Explore Stainless Steel for Your Next Part
Now that you understand stainless steel properties and how the grades compare, the next step is putting the right one to work.
Whether you need a formed 304 enclosure or a machined 316 component, our team helps you pick the grade, optimize the design, and make the part to spec.
Material selection guidance included. No minimum order quantity. ISO 9001 & AS9100 certified.
Not ready to commit to a grade? Contact our engineers to discuss your application environment and get a recommendation for the right stainless steel grade.