Stainless Steel 429
AISI/SAE 429 · UNS S42900
429 (S42900) is a straight-chromium ferritic stainless with slightly lower chromium than 430, a composition that improves weldability while keeping oxidation resistance to 815 °C.
Values for the Annealed condition
429 tempers and conditions
429 is supplied in 3 conditions, soft to hard. Annealed is the default FabDigit quotes; the values on this page are for it.
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
AnnealedDefault 760–830 °C anneal, air or slow cooled | Standard supply condition for sheet, plate, bar and tube; best formability and toughness. | 310 | 490 | 30 | 160 HB | — |
2B | Standard thin-gauge sheet condition for stamped trim, catalytic-converter shells and appliance panels. | 320 | 500 | 30 | 165 HB | 2.9 % IACS |
cold finished bar/wire (annealed then drawn) | Pick for machined fasteners, shafts and screw-machine parts needing closer tolerance and higher strength. | 520 | 620 | 15 | 14 HRC | 2.9 % IACS |
Supply forms, finishes and certifications
Ways 429 is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
HRAP | Hot rolled, annealed and pickled plate/coil | Surface finish |
What is 429?
429 (S42900) is a straight-chromium ferritic stainless with slightly lower chromium than 430, a composition that improves weldability while keeping oxidation resistance to 815 °C. It is supplied as annealed sheet, hot-rolled annealed pickled plate, 2B cold rolled coil and cold drawn bar for welded and formed assemblies, with 310 MPa yield, 490 MPa tensile, 30% elongation and 160 HB. Formability is good for a ferritic (score 65) but stretch forming and chloride pitting resistance stay below 304, and heavy-section welds can coarsen in the HAZ. Use 430 for decorative work or 304 where forming severity and corrosion resistance govern. 429 has a density of 7.7 g/cm³ (0.278 lb/in³), lighter than 83% of stainless steel grades. It melts at 1,427°C (2,601 °F). 429 has a yield strength of 310 MPa (45 ksi) and a tensile strength of 490 MPa (71.1 ksi) — weaker than 63% of stainless steel grades. Elongation at break is 30% and the elastic modulus is 200 GPa (29 Msi).
What is 429 used for?
- Hot water heater tanks and liners
- Automotive trim
- Welded tube and pipe
- Furnace and heat-resistant fixtures
- Appliance panels and housings
- Heat exchanger components in mild environments
- Welded structural sheet assemblies
Advantages
- Conducts heat well — 25 W/m·K (14.4 BTU/hr·ft·°F), better than 93% of stainless steel grades
- Easy to machine — 52/100, better than 91% of stainless steel grades
- Low embodied carbon — 3.5 kg CO₂/kg, better than 88% of stainless steel grades
- High electrical conductivity — 2.9 % IACS, better than 87% of stainless steel grades
- High service temperature — 815°C (1,499 °F), better than 77% of stainless steel grades
Limitations
- Needs corrosion protection — 43/100, worse than 88% of stainless steel grades
429 properties
Typical room-temperature values for 429-Annealed; bars are the position among stainless steel grades.
Physical3
429 has a density of 7.7 g/cm³ (0.278 lb/in³), lighter than 83% of stainless steel grades. It melts at 1,427°C (2,601 °F).
Mechanical13
429 has a yield strength of 310 MPa (45 ksi) and a tensile strength of 490 MPa (71.1 ksi) — weaker than 63% of stainless steel grades. Elongation at break is 30% and the elastic modulus is 200 GPa (29 Msi).
Thermal6
429 is rated for continuous service to 815°C (1,499 °F). It conducts heat at 25 W/m·K (14.4 BTU/hr·ft·°F), better than 93% of stainless steel grades. Thermal expansion is 10.4 µm/m·K (5.78 µin/in·°F).
Electrical3
429 conducts electricity at 2.9 % IACS, better than 87% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is fair (43/100), worse than 88% of stainless steel grades.
Sustainability4
Producing a kilogram of 429 takes about 47 MJ of energy and emits 3.5 kg of CO₂ — less than 87% of stainless steel grades. Typical recycled content is 65%.
Manufacturability7
429's machinability is fair (52/100, better than 91% of stainless steel grades); weldability good (60/100); formability good (65/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the stainless steel family
Yield strength against density for every stainless steel grade FabDigit runs. 429 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 429
Is 429 easy to machine?
Machines like 430 at ~55 % of AISI 1212 — use rigid setups, sharp positive-rake carbide, heavy feeds and flood coolant to avoid work-hardened glazing and stringy chips.
Can 429 be welded?
Readily welded by GTAW/GMAW/resistance methods with 430 or 309L filler; keep heat input low and consider 750–800 °C post-weld anneal to restore weld-HAZ ductility.
Can 429 be formed, bent or molded?
Good deep-drawing and roll-forming in the annealed condition, though springback is higher and stretch-formability lower than austenitic 304; avoid tight bends transverse to rolling on heavy gauge.
Manufacturability
The process limits FabDigit applies to 429. Every 429 part is priced by an engineer; design inside these and the quote comes back without a redesign loop.
Sheet metal
| Formability | Better65 / 100 |
|---|---|
| Weldability | Fair60 / 100 |
| Bendable | Yes |
429 chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| CASTM A240 / A276 | ≤ 0.12 | 0.06 |
| Mn | ≤ 1 | 0.5 |
| Si | ≤ 1 | 0.5 |
| P | ≤ 0.04 | |
| S | ≤ 0.03 | |
| Crlower Cr than 430 improves weld ductility | 14 – 16 | 15 |
| Niresidual limit | ≤ 0.75 | 0.3 |
| Fe | balance |
What surface finishes work on 429?
Passivate in nitric or citric acid (ASTM A967) after machining; takes a bright polish or brushed finish, and can be electropolished — no anodizing.
Surface treatments FabDigit runs on stainless steel parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
Plating
Organic Coating
Black / Phosphate
Thermal Spray
Equivalent designations
Standards and trade names that resolve to Stainless Steel 429 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- S42900
How much does 429 cost?
429 is a premium-cost stainless steel ($$$), cheaper than about 58% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
429 — frequently asked
What is 429 used for?
429 is typically used for hot water heater tanks and liners, automotive trim, welded tube and pipe, furnace and heat-resistant fixtures, appliance panels and housings and heat exchanger components in mild environments. In short: furnace-grade ferritic stainless.
What is the yield strength of 429?
429 has a typical yield strength of 310 MPa (45 ksi) and a tensile strength of 490 MPa (71.1 ksi) — weaker than 63% of stainless steel grades. Strength varies by condition: see the 3 listed tempers.
Is 429 easy to machine?
Reasonably — machinability is rated fair (52/100, better than 91% of stainless steel grades). Machines like 430 at ~55 % of AISI 1212 — use rigid setups, sharp positive-rake carbide, heavy feeds and flood coolant to avoid work-hardened glazing and stringy chips.
Can 429 be welded?
Yes — weldability is rated good (60/100). Readily welded by GTAW/GMAW/resistance methods with 430 or 309L filler; keep heat input low and consider 750–800 °C post-weld anneal to restore weld-HAZ ductility.
What surface finishes work on 429?
Passivate in nitric or citric acid (ASTM A967) after machining; takes a bright polish or brushed finish, and can be electropolished — no anodizing.
Can 429 be formed, bent or molded?
Good deep-drawing and roll-forming in the annealed condition, though springback is higher and stretch-formability lower than austenitic 304; avoid tight bends transverse to rolling on heavy gauge.
What is the maximum service temperature of 429?
429 is rated for continuous use to about 815°C (1,499 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 429 Annealed and 429 CR-2B?
Annealed is the default condition — standard supply condition for sheet, plate, bar and tube; best formability and toughness. CR-2B: standard thin-gauge sheet condition for stamped trim, catalytic-converter shells and appliance panels. Yield strength is 310 MPa in Annealed versus 320 MPa in CR-2B.
How much does 429 cost?
429 is a premium-cost stainless steel ($$$), cheaper than about 58% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Can FabDigit make parts in 429?
Yes — 429 is available for sheet metal; every part is priced by an engineer rather than instantly. Upload a STEP file to get a price and a DFM check.
Sources
- ASTM A240/A240M — Chromium and Chromium-Nickel Stainless Steel Plate, Sheet and Strip — ASTM International (2023)
- ASTM A276/A276M — Stainless Steel Bars and Shapes — ASTM International (2023)
- ASM Specialty Handbook: Stainless Steels — ASM International (1994)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels and High-Performance Alloys — ASM International (1990)
- SAE J405 / UNS S42900 chemical composition — SAE International (2013)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.