904L Stainless Steel Bar
904L bar is a low carbon, high nickel and molybdenum super austenitic stainless steel with strong activation and passivation behaviour. It resists non oxidising acids such as sulphuric, acetic, formic and phosphoric…
What This Product Is For
904L bar is a low carbon, high nickel and molybdenum super austenitic stainless steel with strong activation and passivation behaviour. It resists non oxidising acids such as sulphuric, acetic, formic and phosphoric acid, and it holds up against pitting, crevice corrosion and stress corrosion cracking in neutral chloride media. Bar is produced to ASTM A276 and ASTM A182 or ASME SA-182 in round, square, flat and hexagonal sections.
Key Benefits
- Good activation and passivation conversion ability, which is what keeps the film stable in reducing acids
- Resists pitting in neutral chloride media where standard austenitic bar fails
- Crevice corrosion and stress corrosion resistance for bolting and shafting under load
- Round bar from 3 mm to 800 mm diameter covers pins through to forged shafting
- Supplied with ISO 9001 and third party inspection by SGS or BV
Who It Is For
- Machine shops turning acid service components
- Pump and valve manufacturers specifying super austenitic shafting
- Chemical plant maintenance teams replacing corroded bar stock
- Distributors stocking 904L in multiple bar profiles
Problems It Solves
- 316L shafting that pits and seizes in sulphuric or phosphoric acid
- Stress corrosion cracking on loaded stainless components in chloride service
- Sourcing several bar profiles in the same grade from different mills
- Buyers who need a third party inspection report before release
Application Scenarios
- Pump shafts and valve stems in sulphuric and phosphoric acid duty
- Fasteners and studs in chloride bearing process plant
- Machined fittings for acid handling equipment
- Structural sections inside pickling and plating lines
Specifications
Every value below is taken from the published product data. Where a figure is not published it is left out rather than estimated.
| Standard | ASTM A276, ASTM A182, ASME SA-182 |
|---|---|
| Grade | 904L |
| Round Bar Diameter | 3 mm to 800 mm |
| Square Bar Size | 4 x 4 mm to 100 x 100 mm |
| Flat Bar Thickness | 2 mm to 100 mm |
| Flat Bar Width | 10 mm to 500 mm |
| Hexagonal Bar Size | 2 mm to 100 mm |
| Length | 6 m or customised |
| Certificate | ISO 9001, third party inspection by SGS or BV |
Technical Features
- Low carbon high nickel molybdenum austenitic stainless steel
- Good corrosion resistance in sulphuric, acetic, formic and phosphoric acid
- Good pitting resistance in neutral chloride ion media
- Good crevice corrosion and stress corrosion resistance
- Four bar profiles produced to ASTM A276 and ASTM A182 or ASME SA-182
Materials
- 904L super austenitic stainless steel
Manufacturing Process
- Hot rolling
- Cold drawing
- Peeling and grinding
- Cutting to length
Quality Control
- Chemistry verified to the 904L composition before release
- Diameter, width and thickness checked against the ordered profile
- Third party inspection by SGS or BV arranged where the order calls for it
- ISO 9001 quality system applied to the production route
Certification
- ISO 9001
- Third party inspection by SGS or BV
Customisation Options
- Round, square, flat or hexagonal profile in the same grade
- Length supplied as 6 m or customised to your cut list
- Third party inspection added to the order on request
Use Guide
- Machine with rigid setups and positive feed, because super austenitic grades work harden quickly
- Match the profile to the part, using hexagonal bar for fastener blanks and round bar for shafting
- Ask for the third party inspection report at order stage rather than after shipment
- Pickle and passivate machined surfaces before acid service
How It Compares With the Alternatives
| 316L round bar | 904L adds nickel, molybdenum and copper, which is why it survives non oxidising acids that strip the passive film off 316L |
|---|---|
| 2205 duplex bar | Duplex has higher strength, but 904L is chosen when the medium is reducing acid rather than chloride alone |
| 904L plate | Bar is the right form for turned and machined parts, plate for vessel shells and tube sheets |
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904L Stainless Steel Bar Questions
What bar profiles do you produce
What is the largest round bar diameter
What standards is the bar made to
What is the standard length
Do you provide third party inspection
Which acids does 904L handle
Quote 904L Stainless Steel Bar
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