Material Selection8–10 min read
303 Stainless vs 12L14 Steel vs C36000 Brass for Machined Parts
Compare cycle cost, corrosion requirements and joining limits before choosing free-machining stock.
Author: Mat Grades Editorial DeskRead Guide →
303 Stainless Steel
Primary Designation:TYPE 303
Mat Grades internal verification confirms source-backed fidelity and data integrity. It does not constitute external certification or guaranteed lot conformity. Read engineering disclaimer →
Data Completeness:8 composition elements and 10 condition-specific property values cataloged.
Omitted fields represent unverified properties. "Missing is better than invented."
Key Engineering Properties
Representative source rows, qualified by their reported conditions. Inspect the tables below for all values, limits, and source notes.
Density
7.9 g/cm³TYPICAL · temperature not stated
Thermal Conductivity
16.2 W/(m·K)TYPICAL · at 100 °C
Composition Excerpt
C ≤ 0.15 wt%Carbon (max)
Standard Elemental Basis: MAXTensile Strength
≥ 515 MPaMINIMUM · Cold Finished Annealed Bar · temperature not stated
Engineering Summary
303 Stainless Steel. Source-scoped engineering data is shown with its reported limits and conditions. Unreported properties are not inferred.
Recognized Aliases
Source-backed commercial trade name and short designations cataloged in canonical data.
303 Stainless Steel Specifications & Designations
Standard Designations & Applicable Specifications — Semantically classified designations distinguishing primary standard identifiers, commercial trade names, and applicable specification references.
Direct Standard DesignationsDIRECT DESIGNATION
1 Primary IdentifierScroll horizontally for full designation data
| System | Identifier | Standard System Name | Classification Notes & Provenance |
|---|---|---|---|
| TYPEPRIMARY | 303 | Producer-referenced stainless type | —Ref: Practical Data for Metallurgists, 19th edition |
Applicable Specifications & Product Form ReferencesSPECIFICATION REFERENCE
1 Applicable StandardsScroll horizontally for full standard specifications
| Standards Body | Specification Code | Specification Title / Scope | Relationship Type |
|---|---|---|---|
| 303 | 303 Stainless Steel Engineering Datasheet | Applicable specification reference. | Specification Reference |
Engineering Notice: Applicable specifications establish manufacturing requirements, dimensional tolerances, and test criteria for specific product forms (e.g. bus bar, wire, plate, pipe). They represent applicable technical standards, not alternative or equivalent alloy grades.
303 Stainless Steel Chemical Composition
Chemical Composition (Weight %) — Elemental limits and values from the cited source. Preserves exact semantic limits (minimums, maximums, and ranges).
Scroll horizontally for full elemental limits
| Element | Symbol | Atomic No. | Semantic Basis | Specified Value | Unit | Metallurgical Notes & Qualification | Data Status |
|---|---|---|---|---|---|---|---|
| Carbon | C | 6 | MAXIMUM | ≤ 0.15 | wt% | Source cell: .15max. Scope: p22, Type 303.Ref: Metallus | VERIFIED |
| Manganese | Mn | 25 | MAXIMUM | ≤ 2.00 | wt% | Source cell: 2.00max. Scope: p22, Type 303.Ref: Metallus | VERIFIED |
| Silicon | Si | 14 | MAXIMUM | ≤ 1.00 | wt% | Source cell: 1.00max. Scope: p22, Type 303.Ref: Metallus | VERIFIED |
| Phosphorus | P | 15 | MAXIMUM | ≤ 0.20 | wt% | Source cell: .20max. Scope: p22, Type 303.Ref: Metallus | VERIFIED |
| Sulfur | S | 16 | MINIMUM | ≥ 0.15 | wt% | Source cell: .15min. Scope: p22, Type 303.Ref: Metallus | VERIFIED |
| Chromium | Cr | 24 | RANGE | 17.00 – 19.00 | wt% | Source cell: 17.00/19.00. Scope: p22, Type 303.Ref: Metallus | VERIFIED |
| Nickel | Ni | 28 | RANGE | 8.00 – 10.00 | wt% | Source cell: 8.00/10.00. Scope: p22, Type 303.Ref: Metallus | VERIFIED |
| Molybdenum | Zr, Mo | 42 | EACH | ≤ 0.6 each | wt% | Only when intentionally added (producer option)Zr and Mo each 0.60 wt% maximum at producer option, reported only when intentionally added. No sum or mandatory addition is inferred.Ref: Metallus | VERIFIED |
* Elemental percentages are expressed in weight percent (wt%). Values represent applicable specification limits. Unspecified trace elements are not fabricated or assumed.Preserves exact semantic basis
Property Display UnitsSwitch between Canonical SI and Source / US Customary units:
303 Stainless Steel Physical Properties
Source-specific physical properties. Test temperatures are shown only where reported.
Scroll horizontally for full property parameters
| Property Parameter | Canonical SI Value | Semantic Basis | Test Temperature / Context Range | Source Raw Reference | Source Reference | Status |
|---|---|---|---|---|---|---|
| Density | 7.9 g/cm³ | TYPICAL | 7.90 g/cm3 | Carpenter Technology Corporation | VERIFIED | |
| Elastic Modulus | 193 GPa | TYPICAL | 193 GPa | Carpenter Technology Corporation | VERIFIED | |
| Poisson's Ratio | 0.29 dimensionless | TYPICAL | 0.29 dimensionless | Carpenter Technology Corporation | VERIFIED |
303 Stainless Steel Thermal & Thermodynamic Properties
Phase change temperatures, thermal conductivity, specific heat, mean coefficients of thermal expansion across standardized temperature ranges, and recommended thermal processing windows.
Scroll horizontally for full property parameters
| Property Parameter | Canonical SI Value | Semantic Basis | Test Temperature / Context Range | Source Raw Reference | Source Reference | Status |
|---|---|---|---|---|---|---|
| Coefficient of Thermal Expansion | 17.2 µm/(m·K) | TYPICAL | Test Temp: 100 °C | 17.2 10^-6/K | Carpenter Technology Corporation | VERIFIED |
| Thermal Conductivity | 16.2 W/(m·K) | TYPICAL | Test Temp: 100 °C | 16.2 W/(m·K) | Carpenter Technology Corporation | VERIFIED |
303 Stainless Steel Mechanical Properties
Contextual Mechanical Properties & Tempers: Engineering strength, ductility, and hardness values grouped by product form, temper, and section thickness. Mechanical properties are contextual and not isotropic averages.
Showing 4 of 4 conditions
Scroll horizontally for all conditions & tempers
| Product Form | Temper / Condition | Section Size | Tensile (UTS) | Yield Strength | Elongation | Shear Strength | Fatigue Strength | Hardness (Scales Preserved) | Status |
|---|---|---|---|---|---|---|---|---|---|
| Bar | Cold Finished Annealed Bar · Annealed · Cold FinishedSource values and qualifiersUltimate Tensile Strength: ≥ 515 MPa (MINIMUM)ASTM A582Carpenter Technology Corporation — CarTech Project 70+ 303 Datasheet, Mechanical Properties Table Reduction of Area: ≥ 50 % (MINIMUM)ASTM A582Carpenter Technology Corporation — CarTech Project 70+ 303 Datasheet, Mechanical Properties Table | — | ≥ 515 MPa | — | — | — | — | — | VERIFIED |
| Bar | Cold Finished Annealed Bar · Annealed · Cold FinishedSource values and qualifiersYield Strength: ≥ 205 MPa (MINIMUM)ASTM A582 (0.2% offset)Carpenter Technology Corporation — CarTech Project 70+ 303 Datasheet, Mechanical Properties Table | — | — | ≥ 205 MPa | — | — | — | — | VERIFIED |
| Bar | Cold Finished Annealed Bar · Annealed · Cold FinishedSource values and qualifiersElongation at Break: ≥ 35 % (MINIMUM)ASTM A582Carpenter Technology Corporation — CarTech Project 70+ 303 Datasheet, Mechanical Properties Table | — · in 50 mm (2 in) | — | — | ≥ 35 % | — | — | — | VERIFIED |
| Bar | Cold Finished Annealed BarSource values and qualifiersHRB Hardness: ≤ 95 HRB (MAXIMUM)Carpenter Technology Corporation — CarTech Project 70+ 303 Datasheet, Mechanical Properties Table | — | — | — | — | — | — | ≤ 95 HRB | VERIFIED |
Hardness Integrity Notice: Rockwell B (HRB), Rockwell F (HRF), and Superficial 30T (HR30T) scales are reported on their measured scales without cross-scale mathematical conversion.
Source: See fact-level citations
Practical Engineering & Fabrication Notes
By Mat Grades Editorial Desk · Updated 2026-11-14. Use alongside the specified product standard and supplier certificate.
Machining & shop-floor behavior
For 303 Stainless Steel, a qualified cutting-speed or tool-life recommendation is not supplied in the available record. A relevant hardness example is HRB Hardness: maximum 95 HRB (maximum; Cold Finished Annealed Bar, Bar). Use that supplied condition for a trial of the difficult feature. Record tool changes, burr removal, unclamped dimensions and accepted parts per hour. Relative machinability ratings from different reference scales should not be compared as if they were one common test.
Weldability, brazing & joining
No qualified weld procedure, filler selection or preheat/interpass schedule is established by this material record. Obtain a procedure for the actual joint, supplied condition and section rather than copying one from a nearby grade. The first cataloged strength example is Ultimate Tensile Strength: minimum 515 MPa (minimum; Cold Finished Annealed Bar, Bar). Assess the final part after joining or thermal processing. Include distortion, cleanup and inspection in the quotation. A material designation or favorable process rating is a starting point for qualification, not evidence that an untested joint meets the drawing.
Corrosion & service environment
Assess chlorides, deposits, crevices, temperature and the final cleaned surface together. Stainless is not a promise of immunity to corrosion. Check weld heat tint and embedded iron where fabrication is involved, and do not turn a thermal-property test temperature into a service ceiling. The recorded thermal example is Coefficient of Thermal Expansion: 17.2 µm/(m·K) (typical; ; test temperature 100 °C). State the exposure and inspection access in the design record so that a change of installation or cleaning method triggers a review. The selected composition entries are C maximum 0.15 wt%, Mn maximum 2 wt%, Si maximum 1 wt%. Chemistry documents identity; it does not establish fluid compatibility.
Selection trade-offs & applications
For screw-machined fittings, assess the service exposure before trading 304 for easier cutting. Include the joining and finishing operations in the quote; the stainless family name alone does not approve the finished assembly. The listed forms include Bar; confirm the actual stock offered by the supplier. Compare the complete route through machining, joining, finish and inspection. Keep the certificate, required test location and acceptance criteria with the first-article record. A later change of grade, condition or source should be assessed against that same requirement.
Technical references: Carpenter Technology Corporation; Metallus
Austenitic Steel Alloy Family
Corrosion-resistant stainless steels in the Austenitic metallurgical branch sharing equivalent matrix structures.
303Current Grade
303 Stainless Steel
Related Engineering & Metallurgy Guides
Contextual technical guides explaining degradation mechanisms, testing methodologies, and selection criteria relevant to 303 Stainless Steel.
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Corrosion & Surface Engineering16 min read
How to Polish Stainless Steel: Methods, Scratch Removal, Finishes & Grain Direction
Stainless steel owes its corrosion resistance to a microscopic, self-healing chromium oxide (Cr₂O₃) passive film. Polishing stainless steel is not merely cosmetic cleaning—it is a controlled mechanical abrasion process requiring strict adherence to grain direction, progressive abrasive refinement, and rigorous cross-contamination control to preserve surface integrity and corrosion performance.
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Sources
Sources & Provenance Trail: Authoritative reference publications, standards specifications, and data registers cited across this material record.
MetallusPractical Data for Metallurgists, 19th edition
PRIMARY PRODUCER
Reviewed factual transcription; source document SHA-256 is recorded in the capture metadata. No cross-standard equivalence is asserted.
Carpenter Technology CorporationCarpenter Specialty Alloys Technical Datasheets (Project 70+ 303, CarTech 52100, Custom 630 / 17-4 PH)
PRIMARY PRODUCER
Reviewed factual transcription from primary producer engineering datasheet.
Issuing Body: Carpenter Technology CorporationRevision: Carpenter Specialty Alloys Technical Bulletin 2024View Source Record ↗
Carpenter Technology CorporationCarpenter Specialty Alloys Technical Datasheets (Project 70+ 303, CarTech 52100, Custom 630 / 17-4 PH)
PRIMARY PRODUCER
Reviewed factual transcription from primary producer engineering datasheet.
Issuing Body: Carpenter Technology CorporationRevision: Carpenter Specialty Alloys Technical Bulletin 2024View Source Record ↗
Carpenter Technology CorporationCarpenter Specialty Alloys Technical Datasheets (Project 70+ 303, CarTech 52100, Custom 630 / 17-4 PH)
PRIMARY PRODUCER
Reviewed factual transcription from primary producer engineering datasheet.
Issuing Body: Carpenter Technology CorporationRevision: Carpenter Specialty Alloys Technical Bulletin 2024View Source Record ↗
Carpenter Technology CorporationCarpenter Specialty Alloys Technical Datasheets (Project 70+ 303, CarTech 52100, Custom 630 / 17-4 PH)
PRIMARY PRODUCER
Reviewed factual transcription from primary producer engineering datasheet.
Issuing Body: Carpenter Technology CorporationRevision: Carpenter Specialty Alloys Technical Bulletin 2024View Source Record ↗
Intellectual Property & Provenance Notice: Mat Grades cites technical literature from recognized industry associations and standards organizations. Underlying technical standards and publication data remain the intellectual property of their respective issuing organizations.