ISO 15608 Material Groups

Heat resistant metal (steels) for pressurised applications: Low vanadium alloyed Cr-Mo-(Ni) steels with Mo ≤ 0.7 %, V ≤ 0.1 %, Cr ≤ 0,7 % and Ni ≤ 1,5 %

Features of heat-resistant low-alloyed chromium molybdenum steels ISO 15608 group 4.2

This group contain heat-resistant low-alloyed chromium molybdenum steels (Type 0,5Cr-0,5Mo), in which chromium and molybdenum (in combination) give these steels improved creep strength and corrosion resistance at elevated temperatures.

Welding the steels is only possible with careful welding specifications (preheating temperature, defined heat input and post-weld heat treatment).

Generally speaking, grain size is reduced to reduce pearlite structure, increasing the material’s yield strength. Typical elements that are added to achieve this are titanium, copper, niobium and vanadium. The carbon content of HSLA steel can be anywhere between 0.05 and 0.25% (in mass content) in order to retain formability and weldability. Other elements include, but are not limited to, nickel, chromium, molybdenum and calcium. However, as low-alloy steels, the combined amount of alloying elements (excluding carbon) does mostly not exceed the limit of 2% in mass content.
Typical applications: Components for pressure equipments
Typical yield strength: 240 to 380 MPa

Low vanadium alloyed Cr-Mo-(Ni) steels with lower content of chromium and nickel: see Group 4.1

Typical materials in group 4.2

Name / Grade	Number	Standard	Product	Remarks
T2	K11547	ASTM A-213	Smls. tube	ASME BPVC
F2 T2 P2 FP2	K12122 K12122 K12122 K12122	ASTM A-182 ASTM A-250 ASTM A-335 ASTM A-369	Forging E.R.W. tube Smls. pipe Forged pipe	ASME BPVC ASME BPVC ASME BPVC ASME BPVC
2, Cl. 1 2, Cl. 2	K12143 K12143	ASTM A-387 ASTM A-387	Plate Plate	ASME BPVC ASME BPVC
0.5CR, Cl. 1 0.5CR, Cl. 2	K11547 K11547	ASTM A-691 ASTM A-691	Fusion welded pipe Fusion welded pipe	ASME BPVC ASME BPVV
2, Cl. 1 2, Cl. 2	K12765 K12765	ASTM A-541 ASTM A-541	Forging Forging	ASME BPVC ASME BPVC
CP2	J11547	ASTM A-426	Centrifugal cast pipe	ASME BPVC
WC5	J22000	ASTM A-217	Casting	ASME BPVC

Material Group 5.1 (such 25 CrMo 4): Cr-Mo steels (free of vanadium) with
C ≤ 0,35 %, 0,75 % ≤ Cr < 1,5 % and Mo ≤ 0,7 %;

Features creep resistant steels such as such as 25 CrMo 4 in ISO 15608 Material Group 5.1

This Material group are creep and heat resistant special structural (1Cr–0.5Mo) 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 and also for hydrogen applications. The materials are suitable for temperatures up to 500°C (570°C).

Weldability of typical (1Cr–0.5Mo) steels such as 25 CrMo 4 listed in ISO 15608 Material Group 5.1

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. 100 – 150 °C and max. interpass 300-350 °C. After welding, these steels generally have to be PWHT e.g. 630 – 700°C /2h

Typical materials in group 5.1

Name/Grade	Number	Standard	Product	Remark
25CrMo4 25CrMo4 25CrMo4	1.7218 1.7218 1.7218	EN 10216-2 EN ISO 683-2 EN 10269	Seamless tube Bar (QT) Fasteners	EN 13445-2 & EN 13480-2 Fasteners EN 13445-2 & EN 13480-2
26CrMo4-2	1.7219	EN 10216-4	Seamless tube	EN 13445-2
42CrMo4 42CrMo4	1.7225 1.7225	EN ISO 683-2 EN 10269	Bar (QT) Fasteners	Fasteners EN 13445-2 & EN 13480-2
13CrMo4-5 13CrMo4-5 13CrMo4-5 13CrMo4-5 13CrMo4-5 F12, Cl. 1 T12 T12 P12 FP12	1.7335 1.7335 1.7335 1.7335 1.7335 K11562 K11562 K11562 K11562 K11562	EN 10028-2 EN 10216-2 EN 10222-2 EN 10253-2 EN 10273 ASTM A-182 ASTM A-213 ASTM A-250 ASTM A-335 ASTM A-369	Plate Seamless tube Forging Fittings Bar Forgings Smls. tube E.R.W. tube Pipes Forged pipe	EN 13445-2 & EN 13480-2 EN 13445-2 & EN 13480-2 EN 13445-2 & EN 13480-2 EN 13445-2 & EN 13480-2 EN 13445-2 & EN 13480-2 ASME BPVC ASME BPVC ASME BPVC ASME BPVC ASME BPVC
13CrMo5-5	1.7338	EN 10216-2	Seamless tube	EN 13445-2 & EN 13480-
F12, Cl. 2 F12	K11564 K11564	ASTM A-182 ASTM A-336	Forging Forging	ASME BPVC ASME BPVC
13CrMoSi5-5 F11, Cl. 2 F11, Cl. 3 WP11, Cl. 1 WP11, Cl. 3 F11, Cl. 2 F11, Cl. 3 11, Cl. 4 F11, Cl. 1 T11 T11 T11 P11 P11 F11, Cl. 1 FP11	1.7336 K11572 K11572 – – K11572 K11572 K11572 K11597 K11597 K11597 K11597 K11597 K11597 K11597 K11597	EN 10028-2 ASTM A-182 ASTM A-182 ASTM A-234 ASTM A-234 ASTM A-336 ASTM A-336 ASTM A-445 ASTM A-182 ASTM A-199 ASTM A-213 ASTM A-250 ASTM A-312 ASTM A335 ASTM A-336 ASTM A-369	Plate Forging Forging Fitting Fitting Forging Forging Forging Forging Smls. tube Smls. tube E.R.W. tube Smls. & welded pipe Smls. pipe Forging Forged pipe	EN 13445-2 & EN 13480-2 ASME BPVC ASME BPVC ASME BPVC ASME BPVC ASME BPVC ASME BPVC ASME BPVC ASME BPVC ASME BPVC ASME BPVC ASME BPVC ASME BPVC ASME BPVC ASME BPVC ASME BPVC
12, Cl. 1 12, Cl. 2 1CR, Cl. 1 1CR, Cl. 2	K11757 K11757 K11757 K11757	ASTM A-387 ASTM A-387 ASTM A-691 ASTM A-691	Plate Plate Fusion welded pipe Fusion welded pipe	ASME BPVC ASME BPVC ASME BPVC ASME BPVC
11, Cl. 1 11, Cl. 2 1.25CR, Cl. 1 1.25CR, Cl. 2	K11789 K11789 K11789 K11789	ASTM A-387 ASTM A-387 ASTM A-691 ASTM A-691	Plate Plate Fusion welded pipe Fusion welded pipe	ASME BPVC ASME BPVC ASME BPVC ASME BPVC
B11	K11797	ASTM A-739	Bar	ASME BPVC
WP12, Cl. 1 WP12, Cl. 2	K12062 K12062	ASTM A-234 ASTM A-234	Fitting Fitting	ASME BPVC ASME BPVC
10CrMo5-5 10CrMo5-5	1.7338 1.7338	EN 10216-2 EN 10253-2	Seamless tube Fittings	EN 13445-2 & EN 13480-2 EN 13445-2 & EN 13480-2
CP12	J11562	ASTM A-426	Centrifugal cast pipe	ASME BPVC
G17CrMo5-5 WC6	1.7357 J12072	EN 10213 ASTM A-217	Casting Casting	EN 13445-2 & EN 13480-2 ASME BPVC

Creep Resistant steels

ISO 15608 Group 5.2: Cr-Mo steels (free of vanadium) with
C ≤ 0,35 %, 1,5 % ≤ Cr < 3,5 % and 0,7 < Mo ≤ 1,2 %;

Features creep resistant steels ISO 15608 Material Group 5.2

This Material group are creep and heat resistant special structural (2.25Cr–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 during working processes (welding consumable, surface and atmospheric) 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).

Applications for 2.25Cr–1Mo steels

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).

Cr-Mo steel with an alloy content of 2.25%Cr and 1% Mo is however resilient to such aggressive conditions for an exposure above about 200 °C as are common in hydrogen processes such as petroleum distilling and catalytic reforming which the original rupture strength does not deteriorate.

Weldability of creep resistant steels ISO 15608 Material Group 5.2

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. 150 – 200 °C and max. interpass 300 °C. After welding, these steels generally have to be PWHT e.g. 680 – 720°C /2h.

Typical materials in group 5.2

Name	Number	Standard	Product	Remark
30CrNiMo8	1.6580	EN 10269	Fasteners	EN 13445-2 & EN 13480-2
34CrNiMo6	1.6582	EN 10269	Fasteners	EN 13445-2 & EN 13480-2
12CrMo9-10	1.7375	EN 10028-2	Plate	EN 13445-2 & EN 13480-2
11CrMo9-10 11CrMo9-10 11CrMo9-10	1.7383 1.7383 1.7383	EN 10216-2 EN 10273 EN 10222-2	Seamless tube Bar Forging	EN 13445-2 & EN 13480-2 EN 13445-2 & EN 13480-2 EN 13445-2 & EN 13480-2
G17CrMo9-10	1.7379	EN 10213	Casting	EN 13445-2 & EN 13480-2
22, Cl. 3 22, Cl. 4 22, Cl. 5 B22	K21390 K21390 K21390 K21390	ASTM A-541 ASTM A-541 ASTM A-541 ASTM A-739	Forging Forging Forging Bar	ASME BPVC ASME BPVC ASME BPVC ASME BPVC
10CrMo9-10 10CrMo9-10 10CrMo9-10 10CrMo9-10 F22, Cl. 1 F22, Cl. 3 T22 T22 WP22, Cl. 1 WP22, Cl. 3 T22 P22 F22, Cl. 1 F22, Cl. 3 FP22 22, Cl. 1 22, Cl. 2 22, Cl. 3 A, Cl. 1 A, Cl. 2 A, Cl. 3 A, Cl. 4 A, Cl. 4a B, Cl. 1 B, Cl. 2 B, Cl. 3 B, Cl. 4 B, Cl. 4a 2.25CR, Cl. 1	1.7380 1.7380 1.7380 1.7380 K21590 K21590 K21590 K21590 K21590 K21590 K21590 K21590 K21590 K21590 K21590 K21590 K21590 K21590 K21590 K21590 K21590 K21590 K21590 K21590 K21590 K21590 K21590 K21590 K21590	EN 10028-2 EN 10216-2 EN 10253-2 EN 10273 ASTM A-182 ASTM A-182 ASTM A-199 ASTM A-213 ASTM A-234 ASTM A-234 ASTM A-250 ASTM A-335 ASTM A-336 ASTM A-336 ASTM A-369 ASTM A-387 ASTM A-387 ASTM A-508 ASTM A-542 ASTM A-542 ASTM A-542 ASTM A-542 ASTM A-542 ASTM A-542 ASTM A-542 ASTM A-542 ASTM A-542 ASTM A-542 ASTM A-691	Plate Smls. tube Fittings Bar Forging Forging Smls. tube Smls. tube Fittings Fittings E.R.W. tube Smls. pipe Forging Forging Forged pipe Plate Plate Forging Plate Plate Plate Plate Plate Plate Plate Plate Plate Plate Fusion welded pipe	EN 13445-2 & EN 13480-2 EN 13445-2 & EN 13480-2 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 ASME BPVC ASME BPVC ASME BPVC ASME BPVC ASME BPVC ASME BPVC ASME BPVC ASME BPVC ASME BPVC ASME BPVC ASME BPVC ASME BPVC ASME BPVC ASME BPVC ASME BPVC ASME BPVC
F21 T21 T21 P21 F21, Cl. 1 F21, Cl. 3 FP21 21, Cl. 1 3CR, Cl. 1 3CR, Cl. 2	K31545 K31545 K31545 K31545 K31545 K31545 K31545 K31545 K31545 K31545	ASTM A-182 ASTM A-199 ASTM A-213 ASTM A-335 ASTM A-336 ASTM A-336 ASTM A-369 ASTM A-387 ASTM A-691 ASTM A-691	Forging Smls. tube Smls. tube Smls. pipe Forging Forging Forged pipe Plate Fusion welded pipe Fusion welded pipe	ASME BPVC ASME BPVC ASME BPVC ASME BPVC ASME BPVC ASME BPVC ASME BPVC ASME BPVC ASME BPVC ASME BPVC
WC9 CP22	J21890 J21890	ASTM A-217 ASTM A4-426	Casting Centrifugal cast pipe	ASME BPVC ASME BPVC
10	J22090	ASTM A-356	Casting	ASME BPVC
8, Cl. A 8, Cl. B 8, Cl. C	J22091	ASTM A-487 ASTM A-487 ASTM A-487	Casting Casting Casting	ASME BPVC ASME BPVC ASME BPVC
CP21	J31545	ASTM A-426	Casting	ASME BPVC

EN ISO 15608 Material Group 5.3: Cr-Mo steels (free of vanadium) with
C ≤ 0,35 %, 3,5 % ≤ Cr < 7,0 % and 0,4 < Mo ≤ 0,7 %;

Features of material CrMo such as material no. 1.7362

This Material group are creep and heat resistant special structural (5Cr–0.5Mo) 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).

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).

Applications for creep and heat resistant steels (5Cr–0.5Mo)

Industries that operate equipment under high temperatures can benefit from using chromium molybdenum alloys for boiler, apparatus construction and pressure vessels. for high temperature service These include power stations, energy, oil and gas, chemical, and metal production industries. These materials are often used as the base metal for clad components.

Weldability of Cr-Mo steels ISO 15608 Material Group 5.3

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 350 °C. After welding, these steels generally have to be PWHT e.g. 730 – 760°C.

Typical materials in group 5.3

Name/Grade	Number	Standard	Product	Remarks
GX15CrMo5	1.7365	EN 10213	Casting	EN 13445-2 & EN 13480-2
X16CrMo5-1	1.7366	EN 10222-2	Forging	EN 13445-2 & EN 13480-2
X12CrMo5 X11CrMo5 X11CrMo5 X11CrMo5 F5 T5 T5 WP5, Cl. 1 WP5, Cl. 3 P5 F5 FP5 5, Cl. 1 5, Cl. 2 5CR, Cl. 1 5CR, Cl. 2 – T5c P5c	1.7362 1.7362+I 1.7362+N1&N2 1.7362 K41545 K41545 K41545 K41545 K41545 K41545 K41545 K41545 K41545 K41545 K41545 K41545 – K41245 K41245	EN 10028-2 EN 10216-2 EN 10216-2 EN 10253-2 ASTM A-182 ASTM A-199 ASTM A-213 ASTM A-234 ASTM A-234 ASTM A-335 ASTM S-336 ASTM A-369 ASTM A-387 ASTM A-387 ASTM A-691 ASTM A-691 – ASTM A-213 ASTM A-335	Plate Seamless tube Seamless tube Fitting Forging Smls. tube Smls. tube Fitting Fitting Smls. pipe Forging Forging pipe Plate Plate Fusion welded pipe Fusion welded pipe – Smls. tube Smls. pipe	EN 13445-2 & EN 13480-2 EN 13445-2 & EN 13480-2 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 ASME BPVC ASME BPVC ASME BPVC ASME BPVC ASME BPVC ASME BPVC
C5 CP5	J42045 J42045	ASTM A-217 ASTM A-426	Casting Centrifugal cast pipe	ASME BPVC ASME BPVC
F5a F5A	K42544 K42544	ASTM A-182 ASTM A-336	Forging Forging	ASME BPVC ASME BPVC
T5b P5b	K51545 K51545	ASTM A-213 ASTM A-335	Smls. tube Smls. pipe	ASME BPVC ASME BPVC

ISO 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 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

ISO 15608 Material Group 6.1:
Steels with 0,3 % ≤ Cr < 0,75 %, Mo ≤ 0,7 % and V ≤ 0,35 %;

14MoV6-3 : Features creep and heat resistant steel

This Material group contain creep and heat resistant special structural steels with ferrite–martensite microstructure. Creep resistance Cr-Mo steels with low Vanadium (0.5Cr-0.5Mo-0.25V), 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 (V) steels to have restricted controls at the welding process, therefore, are susceptible to Cold Cracking and Reheat Cracking. Hydrogen induced Cold Cracking.

The steel 14MoV6-3 concept goes back to the dawn of creep resistant steels. Creep rupture strength of steel 14MoV6-3 is superior to that of the higher alloyed steel 10CrMoV9-10. The steel 14MoV6-3 is the exception among the creep resistant, weldable, ferritic boiler and pipe steels, since it is hardening, thus differing substantially from the performance of the other creep resistant, ferritic steels.

It is mainly used in boiler and apparatus construction for boilers, heat exchangers and pressure vessels. The materials are suitable for temperatures up to 560 – 600°C.

Weldability of steel ISO 15608 Material Group 6.1 such 14MoV6-3

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 – 250 °C and max. interpass 300 – 350 °C. After welding, these steels generally have to be PWHT e.g. 700 – 720°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 PWHT e.g. 700 – 720 °C/2 h.

Typical materials in group 6.1

Name	Number	Standard	Product	Remark
14MoV6-3 14MoV6-3	1.7715 1.7715	EN 10216-2 EN 10222-2	Smls. tube Forging	EN 13445-2 & EN 13488-2 EN 13445-2 & EN 13488-2
G12CrMoV5-5	1.7720	EN 10213	Casting	EN 13445-2 & EN 13488-2

ISO 15608 Material Group 6.2: Cr-Mo-V such 13CrMoV9-10
Steels with 0,75 % ≤ Cr < 3,5 %, 0,7 < Mo ≤ 1,2 % and V ≤ 0,35 %

Features of low alloyed Cr-Mo-V steel (2.25Cr-1Mo-0.25V)

CrMo (V) steels with 0.25 % V offer better performance for petrochemical reactors compared to 10CrMo9-10 steels that means the specified yield strength and creep properties for this material is better compared to 10CrMo9-10 steel.

Applications for low alloyed Cr-Mo-V (13CrMoV9-10) steel

This material may be used in all applications requiring service conditions under high temperature and high pressure of hydrogen.

Is particularly suitable for pressure equipment in high temperature hydrogen service (e.g. hydrotreating reactors, exchangers, hydrotreating reactors, hydrodesulfurizers, hydrocrackers)

Welding conditions for 13CrMoV9-10 steel

Welding needs precautions, in particular: tight control of preheat, interpass temperature intermediate stress relieving and post weld heating to avoid cold cracking;

However, the risk of cold cracking is known to occur in the weld metal more frequently than in the HAZ. Therefore, a preheat and minimum interpass temperature of 200°C is recommended for thickness higher than 30 mm. After welding a Dehydrogenation Heat Treatment ≥ 140 °C is recommended. After welding, these steels generally have to be PWHT e.g. 680 °C.

Typical materials in group 6.2

Name/Type	Number	Standard	Product	Remark
7CrMoVTiB10-10+NT	1.7378	EN 10216-2	Smls. tube	EN 13445-2
7CrWVMoNb9-6+NT	1.8201	EN 10216-2	Smls. tube	EN 13445-2
F3V F3V 3V 3V C, Cl. 1 C, Cl. 2 C, Cl. 3 C, Cl. 4 C, Cl. 4a 21V	K31830 K31830 K31830 K31830 K31830 K31830 K31830 K31830 K31830 K31830	ASTM A-182 ASTM A-336 ASTM A-508 ASTM A-541 ASTM A-542 ASTM A-542 ASTM A-542 ASTM A-542 ASTM A-542 ASTM A-832	Forging Forging Forging Forging Plate Plate Plate Plate Plate Plate	ASME BPVC ASME BPVC ASME BPVC ASME BPVC ASME BPVC ASME BPVC ASME BPVC ASME BPVC ASME BPVC ASME BPVC
13CrMoV9-10+NT 13CrMoV9-10+QT F22V F22V 22V D, Cl. 4A 22V	1.7703 1.7703 K31835 K31835 K31835 K31835 K31835	EN 10028-2 EN 10028-2 ASTM A-182 ASTM A-336 ASTM A-541 ASTM A-542 ASTM A-832	Plate Plate Forging Forging Forging Plate Plate	EN 13445-2 & EN 13480-2 EN 13445-2 & EN 13480-2 ASME BPVC ASME BPVC ASME BPVC ASME BPVC ASME BPVC
12CrMoV12-10+NT 12CrMoV12-10+QT F3VCb 3VCb F3VCb 3VCb E, Cl. 4a	1.7767 1.7767 K31390 K31390 K31390 K31390 K31390	EN 10028-2 EN 10028-2 ASTM A-182 ASTM A-336 ASTM A-508 ASTM A-541 ASTM A-542	Plate Plate Forging Forging Forging Forging Plate	EN 13445-2 & EN 13480-2 EN 13445-2 & EN 13480-2 ASME BPVC ASME BPVC ASME BPVC ASME BPVC ASME BPVC
G17CrMoV5-10	1.7706	EN 10213	Casting	EN 13445-2
23V	–	ASTM A-832	Plate	ASME BPVC
8	J11697	ASTM A-356	Casting	ASME BPVC
9	J21610	ASTM A-356	Casting	ASME BPVC

ISO 15608 Material Group 6.3: Cr-Mo-V Steels such as material no. 1.7779 with
3,5 % ≤ Cr < 7,0 %, Mo ≤ 0,7 % and 0,45 < V ≤ 0,55 % such as material no. 1.7779

Features of low alloyed Cr-Mo-V steel (2.25Cr–1Mo–V)

Hydrosteel CrMo (V) steels with 0.5 % V offer better performance for petrochemical reactors compared to 10CrMo9-10 steels that means the specified yield strength and creep properties for this material is a lot of better compared to 10CrMo9-10 steel.
Depending on the heat treatment, the yield strength of 20CrMoV13-5-5 steel is in the range of Rp0,2 = 520 – 640 MPa.

Applications for low alloyed Cr-Mo-V (20CrMoV13-5-5) steel

This material may be used in all applications requiring service conditions under high temperature and high pressure of hydrogen. Steel for hydrogen service an elevated temperature and pressure is stell that not readily susceptible to decarbusation by hydrogen at elevated pressures and temperatures and thus to hydrogen and grain boundary embitterment. This characteristic is achieved ba adding alloying elements that from carbides at the operating temperature.

Is particularly suitable for pressure equipment in high temperature hydrogen service (e.g. hydro treating reactors, exchangers, hydro treating reactors, hydro desulfurizers, hydro crackers)

Welding conditions for 20CrMoV13-5-5 steel

Welding needs precautions, in particular: tight control of preheat, interpass temperature intermediate stress relieving and post weld heating to avoid cold cracking;

Weld metal and HAZ in the as welded condition are susceptible to hydrogen induced cold cracking.

However, the risk of cold cracking is known to occur in the weld metal more frequently than in the HAZ. Therefore, a preheat and minimum interpass temperature of 200°C is recommended for thickness higher than 30 mm. After welding a Dehydrogenation Heat Treatment ≥ 300 °C is recommended. After welding, these steels generally have to be PWHT e.g. 700 -730 °C.

Name	Number	Standard	Product	Remark
20CrMoV13-5-5 D, Cl. 4a	1.7779 K31835	EN 10216-2 ASTM A-542	Smls. tube Forging	EN 13445-2 & EN 13480-2 ASME BPVC

ISO 15608 Material Group 6.4: Steels such as material X10CrMoVNb9-1 with
7,0 % ≤ Cr < 12,5 %, 0,7 < Mo ≤ 1,2 % and V ≤ 0,35 %;

High-temperature martensitic steels above 7% Cr in CrMo steels leads to a group of steels containing martensite. This microstructure introduces a new element of structural hardening. Martensite is characterized by a high dislocation density and a fine lath structure stabilized. This structural hardening is responsible for the large increase in the high creep-rupture strength of e.g. X10CrMoVNb9-1. Further improvements, especially of the creep strength, have been achieved by alloying with vanadium, niobium, tungsten and boron. The modified 9 % Cr steel X10CrMoVNb9-1 (T91 & P91) is now used in power plants all over the world, both in new plants and in refurbishment work of high-pressure/high-temperature piping systems. Subsequently, new steel grades like X11CrMoWVNb9-1-1 (T911 & P911), developed based on T91 & P91. These grades represent the current state of development for creep-resistant ferritic steels.

Weldability of chromium-molybdenum alloyed steels ISO 15608 Material Group 6.4 such as X10CrMoVNb9-1

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. 150 -300 °C. The working temperature should not reach 350°C. After welding, these steels generally have to be annealed e.g. 730 – 760 °C. Before the necessary tempering annealing (740 – 760°C), intermediate cooling to room temperature is required in order to achieve complete martensite transformation.

The filler metals used are essentially alloyed grades of the same type. Only under these conditions can the welded joint be expected to have the same creep rupture strength as the base material.
As the welding technology has a significant influence on the achievable toughness properties in the weld metal, the use of multi-layer technology, i.e. low layer thickness, is recommended in order to achieve a high proportion of tempered weld metal structure and thus an improved toughness level.

Typical materials in group 6.4

Name/Grade	Number	Standard	Product	Remarks/Trade Marks
X10CrMoVNb9-1 X10CrMoVNb9-1 X10CrMoVNb9-1 X10CrMoVNb9-1 F91 T91 WP91 P91 F91 FP91 91, Cl. 2	1.4903 1.4903 1.4903 1.4903 K90901 K90901 K90901 K90901 K90901 K90901 K90901	EN 10028-2 EN 10216-2 EN 10222-2 EN 10253-2 ASTM A-182 ASTM A-213 ASTM A-234 ASTM A-335 ASTM A-336 ASTM A-369 ASTM A-387	Plate Smls. tube Forgings Fittings Forging Smls. tube Fitting Smls. pipe Forging Forged pipe Plate	EN 13445-2 & EN 13480-2 EN 13445-2 & EN 13480-2 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
X10CrWMoVNb9-2 X10CrWMoVNb9-2 F92 T92 WP92 P92 F92 FP92 92	1.4901 1.4901 K92460 K92460 K92460 K92460 K92460 K92460 K92460	EN 10216-2 EN 10253-2 ASTM A-182 ASTM A-213 ASTM A-234 ASTM A-335 ASTM A-336 ASTM A-369 ASTM A-1017	Smls. tube Fittings Forging Smls. tube Fitting Smls. pipe Forging Forged pipe 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
91	K91560	ASTM A-691	Fusion welded pipe	ASME BPVC
X11CrMoWVNb9-1-1 X11CrMoWVNb9-1-1 P911	1.4905 1.4905 –	EN 10216-2 EN 10302 –	Smls. tube – –	EN 13445-2 & EN 13480-2 EN 13445-2 & EN 13480-2 –
X20CrMoV11-1 X20CrMoV11-1 X20CrMoV11-1	1.4922 1.4922 1.4922	EN 10216-22 EN 10222-2 EN 10253-2	Smls. tube Forging Fitting	EN 13445-2 & EN 13480-2 EN 13445-2 & EN 13480-2 EN 13445-2 & EN 13480-2
X22CrMoV12-1	1.4923	EN 10269	Fasteners	EN 13445-2 & EN 13480-2
GX23CrMoV12-1 C12A 12A C91	1.4931 J84090 J84090 J84090	EN 10213 ASTM A-213 ASTM A-356 ASTM A-1091	Casting Casting Casting Casting	EN 13445-2 & EN 13480-2 ASME BPVC ASME BPVC ASME BPVC