Research Article

Ageing Effects on Microstructure, Mechanical Properties, and Fracture Behaviour of 9Cr-1.5Mo-1Co-VNbBN Martensitic Steel Welded Joint for High Temperature Application

Table 2

Mean chemical composition (metallic part) in at.% of precipitate phases in CB2 weld regions and material states and calculated equilibrium phase composition at 625°C.

Material statePhaseBMWM
VCrFeNbMoVCrFeNbMo

PWHT (730°C/24 h)MX6217514260151222
M23C636523182632717

Isothermally aged (625°C/30 kh)MX6414812265153152
M23C626723172692117
Laves phase1145023311846233
Z-phase39331311439401065
MC2218353422172545

Equilibrium calculated
at 625°C
M23C637417063.37317.706
Laves 01646033.3015.346033.5
Z-phase3543.56.51503843.7612.30
MC10.10.2089.20.512.80.2086.50.5

also 4.7 at.% Si in BM and 5.2 at.% Si in WM.