1.4828 (X15CrNiSi20-12) Open-Die Forgings

• EN number1.4828
• EN nameX15CrNiSi20-12
• Similar toAISI 309 · S30900
• Scaling in airto approx. 1000 °C
• StructureAustenitic
• Hardnessmax 223 HB
• Forging range1150–800 °C
• ConditionSolution annealed

Designations and cross-references

1.4828 appears under the designations below. Anything marked similar is not chemically identical and is not a drop-in substitute on a purchase order.

Chemical composition

EN 10095 lists silicon as 1.5 to 2.5 %; some published grade data narrows the band to 1.5 to 2.0 %. Where scaling resistance drives the application, state the silicon band you require on the enquiry. Melting route: EAF plus VOD, with ESR available on request.

Mechanical properties

Published tensile figures for this grade vary with product form and source, commonly quoted as 500 to 700 MPa or 500 to 720 MPa. Acceptance values for a given forging depend on section thickness, test location and the ordering standard, which for open-die stainless forgings is EN 10250-4. Ask us to confirm guaranteed values against the mill certificate before you design to a number.

Physical properties

Density

approx. 7.9 kg/dm³ (0.285 lb/in³)

Electrical resistivity at 20 °C

0.85 Ω·mm²/m

Magnetic response

Not magnetic in the solution annealed condition; becomes magnetisable after cold working

Structure class

Heat-resistant austenitic stainless steel

Scaling resistance in air

up to approx. 1000 °C

Thermal conductivity, specific heat capacity, thermal expansion and modulus of elasticity are available on request from the mill data sheet for the heat supplied.

Temperature limits in service

The elevated silicon content is what gives 1.4828 its scale resistance in air up to roughly 1000 °C. Resistance in carburising and in nitrogen-bearing, oxygen-poor gases is average, in the region of 900 °C. Resistance to sulphur-bearing oxidising and reducing gases is low, so service in those atmospheres is normally held below 650 °C.

Corrosion behaviour

Corrosion resistance is somewhat lower than that of other austenitic stainless steels: this grade is selected for heat resistance, not for wet service. It withstands many chemical influences at elevated temperature, but for chloride-bearing or seawater duty it is the wrong choice and we would point you to a duplex or high-alloy grade instead. Tell us the medium, concentration and temperature and we will confirm suitability before you order.

Forging, heat treatment, machining and welding

Hot forming

1150 to 800 °C, followed by rapid cooling in air or water. Preheat slowly and evenly, and keep the stock free of oil, grease and scale before hot working.

Solution annealing

1050 to 1150 °C, cooling in air or water.

Forgeability

Good.

Machinability

Average. Carbide formation raises tool wear, the steel work-hardens readily and conducts heat poorly, so use coated carbide tooling with generous cooling. As a guide for material at 520 to 600 MPa: about 100 m/min at 6 mm depth of cut, 130 m/min at 3 mm, 150 m/min at 1 mm.

Welding

Good. Suitable for TIG, MAG solid wire, manual arc and laser beam welding. Preheat is not necessary, interpass temperature should not exceed 150 °C, and post-weld heat treatment is not normally applied.

Distortion control

Austenitic steels carry roughly 30 % of the thermal conductivity of unalloyed steels and expand considerably more, so weld with lower heat input and plan against distortion: back-step sequencing, welding alternately on opposite sides of a double-V butt weld, and two welders on large components. Above 12 mm thickness prefer a double-V to a single-V preparation, with an included angle of 60 to 70 degrees, or about 50 degrees for MIG.

1.4828 compared with 1.4833

These two neighbouring heat-resistant austenitic grades are often cross-shopped, and the original enquiry is frequently written against the wrong one.

If your drawing calls for a higher air temperature than 1.4828 supports, ask us about the higher chromium and nickel heat-resistant grades; they cost more in alloy but extend the range.

1.4828 forged products we supply

Everything below is open-die forged or ring-rolled to drawing, rough or finish machined as required.

Where these parts run

Typical duty for the grade covers furnace construction, heat-stressed components in automotive and mechanical engineering, and components for the chemical industry working at high temperature. In our order book that means furnace furniture and hot furnace internals, heat-treatment fixtures, recuperator and hot-gas hardware, refining and petrochemical internals, and heavy machinery parts that run hot. Where sulphur-bearing gas, flue gas or chlorides are present, check the temperature and corrosion sections above before settling on 1.4828.

Testing, inspection and certificates

Ordering standard

EN 10250-4 for open-die stainless forgings, with analysis and mechanical testing in the delivered heat-treatment condition

Ultrasonic examination

EN 10228-3, SEP 1921 or ASTM A388, acceptance class stated on the order

Inspection documents

EN 10204 type 3.1, or type 3.2 where a third party is involved

On request

PMI verification, dye penetrant examination, intergranular corrosion testing, dimensional reports

Questions we get asked about 1.4828