ISO/TR 15608 Material Group 5.4: Cr-Mo steels (free of vanadium) with
C ≤ 0,35 %, 7,0 % ≤ Cr < 10,0 % and 0,7 < Mo ≤ 1,2 %;
X11CrMo9-1: Features creep and heat resistant steel
This Material group are creep and heat resistant special structural (9Cr–1Mo) steels with ferrite–martensite microstructure. Creep resistance steels (well-known as CrMo steels), contain strong carbide and/or nitride forming elements. These are intended to provide a fine dispersion of precipitates that both increase the tensile strength and prevents the formation of the voids. Also, this increase the hardenability (the ability to form martensite). These facts obligate the CrMo steels to have restricted controls at the welding process, therefore, are susceptible to Cold Cracking and Reheat Cracking. Hydrogen induced Cold Cracking.
It is mainly used in boiler and apparatus construction for boiler drums and pressure vessels. The materials are suitable for temperatures up to 550°C (590°C).
Weldability of steel ISO/TR 15608 Material Group 5.4 such X11CrMo9-1
The chromium-molybdenum alloyed heat-resistant steels are generally welded with a preheating suitable for the steel grade and wall thickness in question e.g. min. 200 °C and max. interpass 300 – 350 °C. After welding, these steels generally have to be PWHT e.g. 730 – 760°C /2h.
The chromium-molybdenum alloyed heat-resistant steels are generally welded with a preheating suitable for the steel grade and wall thickness in question e.g. 300 -350 °C. After welding, these steels generally have to be annealed e.g. 730 – 760 °C.
Typical materials
| Name/Grade | Number | Standard | Product | Remarks/Trade Mark |
|---|---|---|---|---|
| X11CrMo9-1+NT1&NT2 X11CrMo9-1+NT F9 T9 WP9, Cl. 1 WP9, Cl. 3 P9 F9 FP9 9, Cl. 1 9, Cl. 2 | 1.7386 1.7386 K90941 K90941 K90941 K90941 K90941 K90941 K90941 K90941 K90941 | EN 10216-2 EN 10253-2 ASTM A-182 ASTM A-213 ASTM A-234 ASTM A-234 ASTM A-335 ASTM A-336 ASTM A-366 ASTM A-387 ASTM A-387 | Smls. tube Fitting Forging Smls. tube Fitting Fitting Smls. pipe Forging Forged pipe Plate Plate | EN 13445-2 & EN 13480-2 EN 13445-2 & EN 13480-2 ASME BPVC ASME BPVC ASME BPVC ASME BPVC ASME BPVC ASME BPVC ASME BPVC ASME BPVC ASME BPVC |
| T9 | K81590 | ASTM A-199 | Smls. tube | ASME BPVC |
| C12 CP9 | J82090 J82090 | ASTM A-217 ASTM A-426 | Casting Centrifugal cast pipe | ASME BPVC ASME BPVC |