1.4903 (X10CrMoVNb9-1) Material Data Sheet

What is 1.4903 (X10CrMoVNb9-1)

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 (X10CrMoVNb9-1 / P91) is a high-temperature strength steel which, compared to 1.4923, has a lower carbon content but is additionally alloyed with molybdenum, vanadium, and niobium (Nb).

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

International identifiers

ASTM A182 (F91), ASTM A336, UNS K90901

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Properties of the material 1.4903 (X10CrMoVNb9-1)

Properties

Weldability	good
Polishing	is possible
Machinability:	4 (1 = not good - 10 = good)
Corrosion resistance 0 - 5	2 (0 = poor - 5 = good)

Welding: Weldable using TIG, MAG (solid wire), arc welding and submerged arc welding (SAW)
Oxy-fuel welding: Not suitable
Use of matching filler materials recommended
Stress-relief annealing after welding recommended
Forging: Heat to approx. 1,150 °C
Forging temperature: 1,150–900 °C
Subsequent air cooling
Machining: Possible in the quenched and tempered condition
Low cutting speeds of approx. 30–50 m/min recommended
Low feed rate and sufficient cooling required
Due to the low thermal conductivity, attention should be paid to tool life
Good polishability

Mechanical properties

Mechanical properties at room temperature:

Rp0,2	A	Z	KV
N/mm²	%	%	J
≥ 450	≥ 20	≥ 40	≥ 68

Physical properties

Density (kg/dm³)	7,75
Electrical resistivity at 20°C (Ω mm² /m)	0,50
Thermal conductivity at 20°C (W/m K)	26
Thermal conductivity at 500°C (W/m K)	30
Specific heat capacity at 20°C (J/kg K)	430
Specific heat capacity at 500°C (J/kg K)	680
Modulus of Elasticity at 20°C (GPa)	218
Modulus of Elasticity at 500°C (GPa)	180

Special properties

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

Processing

Cold forming	not common
Cold upsetting	not common
Free-form and drop forging	is possible
Machining	possible

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Heat treatment 1.4903

	Temperature	Cooling
Hot forming	1200°C - 1100°C	Air
Heat treatment
Quenched and Tempered (+QT)	1040°C - 1100°C	Oil
	730°C - 780°C (>1h dwell time)

Heat treatment: Solution annealing
Heating to 1,040–1,100 °C
Subsequent oil quenching
Tempering temperature: typically 730–780 °C
Tempering temperature and holding time depend on the desired final hardness
Also recommended before welding larger section thicknesses

Chemical composition of 1.4903

1.4903 X10CrMoVNb9-1	C	Si	Mn	P	S	Cr	Mo	Ni
min.	0,08	0,20	0,30			8,0	0,85
max.	0,12	0,50	0,60	0,02	0,01	9,5	1,05	0,4

1.4903 X10CrMoVNb9-1	Al	Cu	N	Nb	Ti	V
min.			0,03	0,06		0,18
max.	0,03		0,07	0,10	0,010	0,25

Areas of application for 1.4903

Instructions for use

Suitable for applications involving high temperatures and continuous thermal loads.
The material’s creep strength and high-temperature yield strength are particularly important.
Suitable for components where mechanical properties must remain relatively stable at elevated temperatures.
When designing components, particular attention should be paid to the change in the modulus of elasticity at increasing temperatures and the material’s behaviour under continuous load.

Areas of application

Energy technology
Turbine construction
General applications for components exposed to high temperatures, particularly under long-term or continuous loads.

Form of supply and availability of 1.4903

In stock

Available for immediate delivery from stock

Form of supply

Flat, forged, quenched and tempered

1.4903 normally delivery condition +QT:

	+QT
Tensile strength (Rm)	620 - 850 N/mm² (Rm)
Hardness acc. to Brinell	200 - 248 HB

Sawn blank

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.