1.4903 (X10CrMoVNb9-1) quenched and tempered

1.4903 is a high-temperature resistant, martensitic (structure of heat-treatable material used) high-alloyed chromium-molybdenum-steel, which is used for mixed-pressure turbine elements by improved properties compared with common steel (10CrMo9-10). With its higher amount of  chrome and molybdenum together with nitrogen (0,03-0,07%) and vanadium (> 0,18 %) it is possible to substitute nickel it still work at more than 500°C in permanent load.

1.4903 is defined with the material designation type F91 according to ASTM Standard.

1.4903 normally delivery condition +QT:

Mechanical properties at room temperature:

Field of application

The main fields of application of this stainless steel are typically power engineering (turbines). Advantages in these application are its properties like creep rupture behavior and proof stress at elevated temperature, and additional the behavior of the Modulus of Elasticity at elevated temperatures, and the sum of these properties with permanent load.

That´s why it is also used in power plants, general engineering, energy industry, boiler (steam boiler, boiler parts, boiler drums) and for pressure vessels in apparatus.

Welding: Parts made of 1.4903 steel can readily be welded using any of the standard welding methods.

After welding the material must be subsequent stress annealed at a temperature between 20 – 40 Kelvin (appr. 700°C) below of tempering temperatures.

Machining: The machinability of this quenched and tempered steel is directly related to its real properties after heat treatment. The best approach is to use a cutting speed at (30-50 [m/min] only.

The high-alloyed state needs a very good cooling for cutting tools (to meet good service life).

Heat treatment

The heat treatment that apply to 1.4903 steel is solution annealing: Heat to 1040 to 1100°C and subsequent cooling by oil quenching. Tempering temperature and time at temperature primarily depend on desired final hardness (730-780°C mostly). Before welding on bigger section thickness it is recommend, too.

Processing
 

Physical properties:

Special properties:

• preferential used at temperatures from 300°C to > 600°C

• magnetisable

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The processing with the saw is a mechanical processing of the material, which results in a significantly lower unintended deformation and increased hardness for the existing structure, such as the thermal cutting.

Thus, the machined workpiece has a homogeneous structure even at the edge, which does not change in the continuation of the material.

This circumstance allows immediate finishing of the workpiece with milling or drilling . So it is not necessary to anneal the material or make a similar operation beforehand.