302 Stainless Steel: Properties, Spring Wire and Forming Applications

Written by: Emma, Technical Sales Engineer  |  Reviewed by: Ethan, Materials Engineer  |  Updated: August 2026

302 stainless steel (UNS S30200) is one of the oldest and best-known austenitic grades — the classic “18-8” stainless that helped define the 300 series. Today it is most often specified for one reason: its strong work-hardening response makes it an excellent choice for spring wire, wire forms, clips, and fasteners. This article explains what 302 is, how cold working gives it strength, why it is a standard spring-wire material, and what buyers should check when specifying it.

1. What Is 302 Stainless Steel?

302 is a chromium–nickel austenitic stainless steel with a typical composition of about 17–19% chromium and 8–10% nickel. It has a face-centered cubic (FCC) structure, is typically non-magnetic in the annealed condition, and — like other austenitic grades — cannot be hardened by heat treatment. Its strength is developed almost entirely through cold working.

That last point is central to understanding 302. A heat-treatable steel gains strength through quenching and tempering; 302 gains strength through rolling, drawing, and forming. This work-hardenable character, combined with useful corrosion resistance, is what makes 302 a workhorse for wire-based spring and fastener applications.

2. Chemical Composition and Metallurgical Characteristics

The table below shows typical specification limits for S30200. Exact limits vary slightly between standards and product forms, so the governing specification should always be confirmed.

The chromium provides corrosion resistance through a passive surface film, while the nickel stabilizes the austenitic structure. 302’s relatively high carbon (compared with low-carbon grades such as 304L) and its moderately stable austenite mean it work-hardens readily — the metallurgical basis for its use in spring wire.

3. Mechanical Properties in Annealed and Cold-Worked Conditions

302 is supplied across a wide range of conditions, from fully annealed to heavily cold-worked. In the annealed condition it is soft, ductile, and formable, with relatively low strength. As the material is cold-worked toward conditions such as quarter-hard, half-hard, three-quarter-hard, and full-hard, its strength and hardness rise while its elongation falls.

The table below is a relative guide to how the condition changes behavior; it is not a substitute for the mechanical property values defined in the applicable standard for the specific product form and size.

Mechanical property values are not interchangeable across product forms. Wire, strip, sheet, and bar are produced to different standards and size ranges, and a strength figure for one form should not be assumed for another. Always verify against the applicable ASTM specification and the mill test certificate.

4. Work Hardening: Why 302 Gains Strength During Cold Working

Work hardening is the process by which plastic deformation raises a metal’s strength. In 302, cold rolling and wire drawing do two things at once: they multiply dislocations within the crystal structure and, because 302’s austenite is not fully stable, partially transform the structure to martensite. Both effects raise strength and hardness while reducing ductility.

This is why 302 cannot be described by a single strength value. The same grade delivered as soft annealed wire and as hard-drawn spring wire will behave very differently, and the amount of cold reduction — captured in the temper or cold-work condition — is the key purchasing variable. Because 302 is not heat-treatable, cold working is the only route to its higher strength levels.

5. 302 Stainless Steel for Spring Wire

302 is a long-established material for stainless spring wire. Its work-hardening response gives spring wire the combination of strength and elastic recovery that a spring needs to deflect and return without taking a permanent set. Typical procurement scenarios include spring wire, wire forms, clips, fasteners, and light-duty springs, often produced to ASTM A313 (spring wire) or ASTM A580 (wire).

For spring service, the finished performance depends heavily on three things: the wire diameter, the cold-work condition or temper, and the specific standard the material is ordered to. A spring made from annealed wire behaves differently from one made from hard-drawn wire, and smaller diameters generally reach higher strength levels for a given degree of cold work. Buyers should therefore specify the wire diameter, the temper or cold-work condition, and the applicable standard together rather than ordering “302 wire” generically.

6. Forming, Bending and Drawing Considerations

Formability in 302 is governed by condition. Annealed material bends, forms, and draws readily; harder tempers resist deformation and spring back strongly. This is why the annealed condition is chosen for deep drawing and complex forming, while cold-worked conditions are reserved for parts that need only light bending or coiling after the material has already reached its working strength.

Springback deserves particular attention. As 302 is cold-worked to higher strength, it returns more strongly toward its original shape after bending, so tooling must be compensated accordingly. A forming route that works in annealed 302 will not necessarily work in half-hard or full-hard material, and the temper must be matched to the intended forming operations.

7. Corrosion Resistance and Service Limits

302 offers good corrosion resistance in normal atmospheric and general industrial environments, comparable in character to other 18-8 grades. That does not make it suitable for every environment. Performance in chloride-bearing, marine, or aggressive chemical service depends on concentration, temperature, humidity, surface condition, and applied stress, and 302 should not be assumed adequate for those conditions without review.

As with all austenitic grades, corrosion resistance is also affected by the material’s condition and finishing. Heavily cold-worked material with residual stress, or a part with surface contamination, may behave differently from clean, well-finished annealed material. Corrosion selection should therefore consider the condition and surface state, not just the grade name.

8. 302 vs 304: When the Similarity Matters and When It Does Not

302 and 304 are closely related 18-8 grades, and in many mild applications they are functionally similar. The differences are in the details: 302 typically has a slightly lower chromium and nickel range and a higher maximum carbon, which gives it a somewhat stronger work-hardening response and makes it the traditional choice for spring wire. 304, with its slightly higher alloy content and common low-carbon 304L variant, is more widely used for general fabrication and welded work.

The similarity matters where corrosion and general fabrication are the priority, and the two grades may often be considered together. The difference matters where cold-worked strength and spring performance are the priority — there, 302’s work-hardening character is the reason it is specified. This article is about 302 specifically; the point is simply to understand how it relates to its better-known neighbor, not to treat the two as interchangeable.

9. Product Forms, Standards and Purchasing Requirements

302 is available in multiple product forms, each covered by its own standard. The applicable standard depends on the form being purchased, and the standard defines the composition limits, property requirements, and tolerances that apply.

A purchase order for 302 should state the grade and UNS, product form, dimensions, temper or cold-work condition, surface finish, the applicable ASTM specification, and the required documentation (such as a mill test certificate). Omitting any of these — especially the temper or cold-work condition — leaves the order open to a material that does not match the intended use.

10. Common Purchasing Mistakes

• Ordering “302 stainless steel” without a UNS or standard — the grade, form, and condition are left undefined.
• Not specifying the temper or cold-work condition — especially critical for spring wire, where annealed and hard-drawn wire behave very differently.
• Mixing property data across product forms — wire, strip, sheet, and bar have different standards and size-dependent properties.
• Assuming 302 can be heat-treated to gain strength — as an austenitic grade, it hardens only through cold work.
• Treating 302 as a drop-in substitute for 304 — the grades are similar but not interchangeable without checking the application.
• Ignoring springback — harder tempers spring back more and require compensated tooling.

11. How to Specify 302 Stainless Steel

A complete specification removes ambiguity. A practical example for spring wire might read:

An RFQ for 302 should include:

• Grade and UNS — 302 (S30200)
• Product form — wire, strip, sheet, plate, or bar
• Dimensions — wire diameter or sheet thickness and width, with tolerances
• Temper or cold-work condition — annealed, hard-drawn, quarter-hard, half-hard, or another defined condition
• Applicable ASTM specification — A313, A580, A666, A276, or the relevant standard
• Surface finish — where applicable
• Documentation — mill test certificate (EN 10204 3.1 or 3.2 where applicable)
• Quantity — clearly stated with units

FAQ

Q1: What is 302 stainless steel?
302 (UNS S30200) is a chromium–nickel austenitic “18-8” stainless steel known for its strong work-hardening response and its use in spring wire and wire forms.

Q2: Is 302 stainless steel magnetic?
In the annealed condition it is typically non-magnetic. Cold working can transform part of the structure to martensite, so heavily cold-worked 302 may show some magnetic response.

Q3: Can 302 be hardened by heat treatment?
No. As an austenitic grade, 302 is not heat-treatable. Its strength is developed through cold working, not through quenching and tempering.

Q4: What is 302 stainless steel used for?
Common uses include spring wire, wire forms, clips, fasteners, and light-duty springs, as well as sheet and strip for formed parts.

Q5: What is the difference between 302 and 304?
The grades are closely related 18-8 alloys. 302 typically has slightly lower chromium and nickel and higher maximum carbon, giving it a stronger work-hardening response, while 304 is more common for general fabrication and welding.

Q6: Is 302 good for springs?
Yes. Its work-hardening response produces the strength and elastic recovery that springs require, making it a standard stainless spring-wire material.

Q7: Is 302 corrosion resistant?
It offers good corrosion resistance in normal atmospheric and general industrial environments, but it is not suitable for all chloride-bearing, marine, or aggressive chemical environments without review.

Q8: How should 302 stainless steel be specified?
State the grade and UNS, product form, dimensions, temper or cold-work condition, applicable ASTM specification, surface finish, mill test certificate, and quantity.