303 stainless steel (UNS S30300) is a sulfur-modified austenitic stainless steel developed for improved machinability and chip formation. It is commonly purchased as precision-machined bar stock for shafts, fittings, fasteners and production screw-machine components. The sulfur addition can reduce corrosion resistance and weldability compared with 304.
Download 303 Stainless Steel Round Bar — Mozaic technical reference (PDF)
303 Stainless Steel Round Bar — Technical Specifications
| Property or designation | Reference information |
|---|---|
| UNS / related designation | S30300; EN 1.4305 / X8CrNiS18-9 for comparison |
| Common free-machining bar specification | ASTM A582/A582M where specified |
| Chromium (Cr) | 17.0–19.0 wt% |
| Nickel (Ni) | 8.0–10.0 wt% |
| Sulfur (S) | 0.15 wt% minimum |
| Carbon (C) | 0.15 wt% maximum |
| Density | Approximately 7.90 g/cm³ (annealed reference) |
| Heat treatment | Not conventionally hardenable by heat treatment |
Technical values shown are general reference information, not a mill test report. Chemical limits and mechanical properties are governed by the applicable material specification, heat/lot and supply condition.
Applications and Grade Comparison
303 is frequently chosen where turning productivity and surface quality take priority, provided the application does not require maximum corrosion resistance, welding, or extensive forming. Compare 304 stainless steel where broader corrosion resistance and fabricability are important, or 316 stainless steel for certain more demanding corrosive environments.
Precision Centerless Grinding and Bar Preparation
Mozaic processes precision ground 303 round bars for CNC and Swiss machining where tight OD and consistent finishes matter. Supply the incoming size, target diameter, length, straightness/roughness requirements, quantity and any required mill certificates. See Mozaic’s centerless grinding services.
Common Questions
Is 303 stainless as corrosion resistant as 304?
Generally not. Sulfur improves machinability but reduces corrosion resistance and weldability relative to standard 304.
Can 303 stainless steel be heat hardened?
It is an austenitic stainless grade and is not hardened by conventional quench-and-temper heat treatment.
Request a Quote
For order-specific sourcing and grinding availability, request a quote, email sales@mozaicprecision.com, or call 847-637-8379.
Reference source: technical grade information. This page is not a substitute for the relevant purchase specification or mill certification.