What Is EN 1.5415 Steel
EN 1.5415 is the numeric designation of 16Mo3, a molybdenum alloyed pressure vessel steel defined in EN 10028-2. The 16 refers to a nominal carbon content of 0.16%, Mo to the molybdenum addition, and 3 to a nominal molybdenum content of 0.30%. The steel is supplied as hot rolled plate in the normalized condition and is the standard material for boiler drums, superheater components, heat exchangers and pressure vessels operating at elevated temperatures.
Chemical Composition
Per EN 10028-2, the main elements of 16Mo3 are limited as follows:
Carbon - 0.12-0.20%, balancing strength with weldability.
Manganese - 0.40-0.90%, for strength and deoxidation.
Silicon - 0.35% maximum.
Molybdenum - 0.25-0.35%, the key alloying element that provides high-temperature creep resistance.
Phosphorus and sulphur - 0.025% maximum each for cleanliness.
Mechanical Properties
Yield strength - 275 MPa minimum for thickness up to 16 mm; 270 MPa for 16-40 mm.
Tensile strength - 440-590 MPa for thickness up to 16 mm.
Elongation - minimum 22% on the longitudinal test piece.
Elevated temperature - the molybdenum addition maintains useful strength well above 400 °C, where plain carbon steels lose capacity rapidly.
Heat Treatment and Delivery Condition
16Mo3 is normally delivered in the normalized condition, normalizing at about 890-950 °C followed by air cooling, which refines the grain structure and ensures consistent mechanical properties. For components that require it, the steel can be post-weld heat treated; the recommended PWHT temperature range is typically 580-620 °C. Welding is performed with low-hydrogen consumables, and preheat is generally applied above about 15 mm thickness.
Applications in Pressure Equipment
Boiler drums and steam receivers - thick plate forming pressure boundaries at elevated temperature.
Heat exchangers - shells, tube plates and nozzles in feed water and steam service.
Pressure vessels - process vessels in refineries, chemical plants and power stations.
Piping components - seamless tubes and fittings of the same grade family.
Supply Forms and Certification
The plate is supplied in thicknesses from 5 mm to 150 mm, widths to 3000 mm and lengths to 12000 mm, with normalized delivery and full ultrasonic testing options. Certificates are issued per EN 10204 type 3.1 or 3.2, and plates can be marked with the heat number for full traceability into the pressure equipment file.
Frequently Asked Questions
Q: What does 1.5415 mean?
It is the numeric steel designation per EN 10027-2; the equivalent name is 16Mo3 per EN 10028-2.
Q: Why is molybdenum added to this steel?
Molybdenum improves creep resistance and high-temperature strength, allowing safe service at temperatures up to about 500 °C.
Q: Can 16Mo3 be welded?
Yes, with low-hydrogen consumables and controlled preheat; the weld procedure is normally qualified per the pressure equipment code.
Q: What is the delivery condition?
The plate is delivered normalized, with the option of additional tempering or stress relieving per the specification.
Q: Which thickness range is available?
Plate from 5 mm to 150 mm is commonly supplied, with widths to 3000 mm and lengths to 12000 mm.
Q: What certificates are provided?
EN 10204 type 3.1 or 3.2 certificates, with ultrasonic testing reports on request.