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 |