16Mo3 / 1.5415 Low-Alloy Pressure Vessel and Boiler Steel

The mechanical properties of 16Mo3 steel vary with nominal thickness and heat treatment condition. The values below are specified for the normalized (+N) delivery condition, which is the most common for pressure vessel applications.

For the quenched and tempered (+QT) condition, 16Mo3 offers slightly different properties:

Additional Mechanical Data

The physical properties of EN 1.5415 (16Mo3) steel are important for engineering calculations involving thermal stress, heat transfer, and electrical applications.

16Mo3 (1.5415) steel has well-established equivalents across international standards. Understanding these cross-references is essential for global procurement and material substitution.

A common question in steel procurement is the distinction between 15Mo3 and 16Mo3. The short answer: they are essentially the same material under different standard designations.

15Mo3 (Old DIN)

• Older DIN standard designation
• Steel number: 1.5415
• Superseded by EN standards
• Same chemical composition range
• Found in legacy drawings and older specifications

16Mo3 (Current EN)

• Current EN 10028-2 designation
• Steel number: 1.5415
• Active European standard
• Same chemical composition range
• Required for new EN-compliant orders

When the European Committee for Standardization (CEN) developed the EN standards to replace national standards like DIN, 15Mo3 was re designated as 16Mo3 under EN 10028-2. The steel number 1.5415 remained unchanged. Both designations refer to the same alloy composition and mechanical property ranges. If your project specifies 15Mo3, ordering 16Mo3 to EN 10028-2 is the correct modern equivalent.

16Mo3 steel is typically supplied in the normalized (+N) condition, which involves heating the material above its upper critical temperature and allowing it to air-cool. This treatment produces a uniform ferrite-pearlite microstructure that provides the specified mechanical properties.

Heat Treatment Parameters

The +N (normalized) condition is the standard delivery condition for most 16Mo3 pressure vessel plates and tubes. The +QT (quenched and tempered) condition may be specified for thicker sections (>250 mm) or when higher yield strength is required. Post-weld heat treatment (PWHT) is strongly recommended after welding to relieve residual stresses and restore the base metal's creep resistance in the heat-affected zone (HAZ).

Important: The heat treatment designation appears as a suffix to the grade name. For example, "16Mo3 +N" means normalized 16Mo3. Always confirm the delivery condition when ordering, as it directly affects the mechanical properties you receive.

16Mo3 (1.5415) steel is primarily used in applications involving elevated temperatures and pressure, where its molybdenum-enhanced creep resistance provides a decisive advantage over carbon steel.

Key Application Areas

• Pressure vessels: Drums, shells, and heads for reactors and separators operating at elevated temperatures
• Steam boilers: Boiler drums, water walls, superheater tubes, and reheater components
• Heat exchangers: Shell-and-tube and plate-type units in refineries and petrochemical plants
• Piping systems: Vaporizer ducts, collector ducts, and process piping in oil, gas, and chemical industries
• Flanges and fittings: Welding-neck flanges, butt-welding pipe fittings, and forged components
• Refinery equipment: Catalytic cracking units, distillation columns, and heat transfer equipment

The steel's maximum continuous service temperature of 530°C makes it suitable for intermediate elevated-temperature service where higher-alloy Cr-Mo steels (such as 13CrMo4-5 / 1.7335) would be unnecessarily expensive. For applications above 530°C, higher chromium-molybdenum grades should be considered.