300 Series Stainless Steel Basics

In the stainless steel family, the 300 series stainless steel stands as workhorse and cornerstone. Predominantly austenitic in structure, these alloys offer an excellent corrosion resistance, formability and weldability, toughness, and non-magnetic properties in the annealed condition. Grades like 304 and 316 have been widely used in various industries, from architecture and food processing to chemical plants, pharmaceuticals, energy generation, and marine environments.

Understanding the 300 series stainless steel basic is critical for engineers, specialists, and fabricators seeking reliable, long-lasting performance. This guide talks the composition, properties, common grades, product forms, and key differentiators that define this essential material family.

What Is 300 Series Stainless Steel?

300 series stainless steels are classified as austenitic chromium-nickel alloys.

The "300" name originates from the American Iron and Steel Institute system, which grouped alloys primarily with Cr and Ni as the major alloying elements into the 3xx range. This naming remains universally recognized.

300 Series Core Chemical Composition

Chromium: Minimum 16%, typically ranging from 16% to 30%. Chromium is the essential element that forms the passive, self-healing chromium oxide layer on the surface, providing the fundamental corrosion resistance.

Nickel: Minimum 7%, typically ranging from 6% to 22%. Nickel is crucial for stabilizing the austenitic crystal structure at room temperature. This structure is responsible for the alloy's excellent ductility, toughness, formability, weldability, and non-magnetic nature when annealed.

Carbon: Generally kept low (<0.08% max, often <0.03% for "L" grades) to minimize sensitization during welding or high-temperature exposure, which can impair corrosion resistance.

300 Series Stainless Steel Properties

300 series austenitic structure imparted by the Cr-Ni balance:

1. Corrosion Resistance: The passive chromium oxide film provides robust resistance to a wide range of environments, including atmospheric exposure, freshwater, many organic acids, foodstuffs, sterilizing solutions, and mild inorganic acids. Mo grades significantly extend resistance to chlorides and reducing acids.

2. Formability: High ductility and work hardening rate allow for deep drawing, spinning, stretching, bending, and other severe forming operations. This is the 300 series stainless steel as a major advantage over ferritic or martensitic grades.

3. Weldability: Most grades are readily weldable by all common fusion and resistance methods. Low-carbon "L" grades or stabilized grades like 321, 347 are used when welding thick sections or where service involves exposure to sensitization temperatures post-weld.

4. Toughness: Retains high impact toughness down to very low temperatures. This is critical for LNG, aerospace, and cryogenic processing applications.

5. Non-Magnetic: Austenitic structure is inherently non-magnetic in the fully annealed condition. Note: Cold working can induce a degree of magnetism near the worked areas.

6. High-Temperature Strength and Oxidation Resistance: Grades like 309/S, 310/S, 316H, 321H, 347H are specifically formulated for service at elevated temperatures, resisting scaling and creep better than standard grades. Stabilized grades prevent sensitization during high-temp service.

7. Hygienic Properties: Smooth, non-porous surface, ease of cleaning, and corrosion resistance make 304L and 316L the standards for food, beverage, pharmaceutical, and medical applications.

300 Series Grades, Properties and Applications

300 series grades composition

Grade	C max	Mn max	Si max	P max	S max	Cr	Ni	Mo	Other
304	0.07	2.00	0.75	0.045	0.030	17.5-19.5	8.0-10.5	-	N 0.10 max
304L	0.030	2.00	0.75	0.045	0.030	18.0-20.0	8.0-12.0	-	N 0.10 max
316	0.07	2.00	0.75	0.045	0.030	16.5-18.5	10.0-13.0	2.00-2.50	N 0.10 max
316L	0.030	2.00	0.75	0.045	0.030	16.5-18.5	10.0-13.0	2.00-2.50	N 0.10 max
316Ti	0.08	2.00	0.75	0.045	0.030	16.5-18.5	10.5-13.5	2.00-2.50	Ti 5xC min/0.70 max
317L	0.030	2.00	0.75	0.045	0.030	18.0-20.0	11.0-15.0	3.0-4.0	N 0.10 max
321	0.08	2.00	0.75	0.045	0.030	17.0-19.0	9.0-12.0	-	Ti 5xC min/0.70 max
347	0.08	2.00	0.75	0.045	0.030	17.0-19.0	9.0-13.0	-	Nb 10xC min/1.10 max
310S	0.08	2.00	1.50	0.045	0.030	24.0-26.0	19.0-22.0	-	-

300 series grades equivalents and applications

Common Grade	Typical Applications	Common Equivalents (ASTM UNS / EN / DIN)
304	Tanks, piping, architectural trim, kitchen equipment, chemical containers.	S30400 / 1.4301 / X5CrNi18-10
304L	Welded assemblies, chemical processing, food/beverage/pharma equipment.	S30403 / 1.4307 / X2CrNi18-9
316	Marine environments, chemical processing (sulfuric acids, chlorides), medical devices.	S31600 / 1.4401 / X5CrNiMo17-12-2
316L	Welded assemblies in corrosive environments, pharmaceutical/biotech, coastal structures.	S31603 / 1.4404 / X2CrNiMo17-12-2
316Ti	High-temperature welded components, exhaust systems.	S31635 / 1.4571 / X6CrNiMoTi17-12-2
317L	Severe chemical environments (sulfite digesters, flue gas desulfurization).	S31703 / 1.4438 / X2CrNiMo18-15-4
321	High-temperature applications (jet engine parts, exhausts), welded assemblies.	S32100 / 1.4541 / X6CrNiTi18-10
321H	Pressure vessels, heat exchangers, high-temp piping.	S32109 / 1.4878 / X12CrNiTi18-9
347	High-temperature welded equipment (boilers, superheaters), chemical processes.	S34700 / 1.4550 / X6CrNiNb18-10
347H	High-temperature pressure vessels, heat exchangers, furnace parts.	S34709 / 1.4912 / X6CrNiNb18-10
310S	Furnace parts, heat treatment equipment, kiln linings, burner tubes.	S31008 / 1.4845 / X8CrNi25-21
316Lmod	Nuclear power plant components (primary piping), critical welded structures.	S31603 (modified) / RCC-M M3301 / -
316H	High-temperature pressure vessels, heat exchangers.	S31609 / 1.4919 / X6CrNiMo17-13-3

300  Series Steel Physical Properties

Property	304/304L	316/316L	321/347	310S
Density (g/cm³)	7.93	7.98	7.98	7.98
Melting Range (°C)	1400-1450	1370-1400	1400-1425	1400-1450
Thermal Expansion (μm/m·°C) 0-100°C	17.3	16.0	16.6	15.0
Thermal Conductivity (W/m·K) 100°C	16.2	16.3	16.3	14.2
Specific Heat (J/kg·K) 0-100°C	500	500	500	500
Electrical Resistivity (μΩ·m)	0.72	0.74	0.72	0.78
Modulus of Elasticity (GPa)	193	193	193	200
Magnetic Permeability (H = 200 Oe)	<1.02	<1.02	<1.02	<1.02

300  Series Steel Mechanical Properties

Grade	Tensile Str Min (MPa)	Yield Str 0.2% Min (MPa)	Elongation Min (%)	Hardness (HB) Max
304	515	205	40	201
304L	485	170	40	201
316	515	205	40	217
316L	485	170	40	217
321	515	205	40	217
347	515	205	40	201
317L	515	205	40	217
310S	515	205	40	217

Note: Properties vary with product form, size, and specific standard requirements. Values are typical minima per common specifications like ASTM A240.

300 Series Stainless Steel Products

Our JN factory specializes in delivering 300 series stainless steel in the comprehensive range of product forms:

300 Series Steel Plate/Sheet: Hot-rolled and cold-rolled, in a wide range of thicknesses, widths, and surface finishes (No. 1, 2B, BA, No. 4, No. 8, HL, custom). 

300 Series Steel Bar: Hot-finished and cold-finished rounds, squares, hexagons, flats. Available in straight lengths or coils. Used for machining shafts, valves, fasteners, fittings, and general fabrication.

300 Series Steel Tubing/Pipe: Seamless and welded, in standard pipe schedules and custom sizes. For fluid transport, instrumentation, heat exchangers, structural applications. Includes both mechanical and pressure pipe.

300 Series Steel Forgings: Open-die and closed-die forgings like valve bodies, pump casings, flanges, fittings, marine shafting. We offer solution annealing and other necessary heat treatments.

300 Series Steel Pipe Fittings and Flanges: Elbows, tees, reducers, caps, stub ends, weld necks, slip-ons, blinds, etc., manufactured to ASME B16.9, B16.11, B16.5, B16.47, MSS-SP-43, -75, -83, DIN, EN, JIS standards. Essential for piping systems.

FAQs

300 Series Stainless Steel vs 304:

Alloy 304 is a specific grade within the 300 series. When someone asks "300 series vs 304", they are likely comparing the general characteristics of the 300 series family to the specific properties of 304. 304 is the most common and versatile grade, representing the baseline Cr-Ni austenitic alloy. 

300 Series vs 400 Series Stainless Steel:

Main Difference: 300 series are austenitic, while 400 series are primarily ferritic or martensitic.

Austenitic 300 series advantages:

• Corrosion Resistance especially in diverse environments.

• Formability and ductility.

• Weldability.

• Low-Temperature toughness.

• Non-magnetic properties.

400 Series Advantages: 

• Lower cost, higher strength, good wear resistance, good oxidation resistance at high temps, magnetic properties. Common grades: 430, 410, 420, 440C .

200 Series vs 300 Series Stainless Steel:

200 series are also austenitic, but replace a significant portion of Nickel (Ni) with Manganese (Mn) and often Nitrogen (N). Grades like 201, 202.

• Properties: Developed as a lower-cost alternative to 304. 

• Lower Corrosion Resistance: Especially in acidic or chloride environments compared to equivalent 300 series grades.

• Lower Nickel Content: Makes them more susceptible to corrosion and can affect high-temperature performance/formability.

• Work Hardening: Often work hardens faster than 304.

• Magnetic: More likely to show magnetic response after cold working

• Uses: Primarily for less demanding applications where cost is paramount and high corrosion resistance isn't critical like some cookware, non-structural automotive trim, sinks, washing machine drums.

Why Choose JN for Purchasing 300 Series Stainless Steel?

At JN, we don't just supply stainless steel; we deliver metallurgical expertise. When you partner with us, you gain:

JN production adheres to the strictest international standards (ASTM, ASME, EN, DIN, JIS, GB) and undergoes rigorous third-party verified testing. 

Our facility holds critical certifications including ISO 9001, ISO 14001, OHSAS 45001, PED, ASME Boiler & Pressure Vessel Code Stamp, and approvals from major classification societies (DNV, ABS, LR, BV, etc.). This ensures global acceptance of our products.

From initial inquiry to final receipt, our experienced technical sales team provides responsive support. We efficiently handle both single orders and high-volume production runs, ensuring consistent quality and reliable on-time delivery. We are your dependable global partner.

Conclusion

300 series austenitic stainless steel remains the basic material where corrosion resistance, formability, weldability, toughness, and hygiene are paramount. JN combines deep metallurgical expertise, comprehensive manufacturing capabilities across all product forms, stringent quality control, and customization to deliver 300 series stainless steel solutions that meet your requirements. Contact our team today to discuss how we can support your project.