CONCLUSION
The ThermoCalc software package, using the thermodynamic databases of
TCFE7 was employed to study the precipitation of nitrides and
carbonitrides in common microalloyed line pipe steels.
- Higher concentration of titanium increases the precipitation
temperatures of titanium nitrides by approximately 70K, suggesting
larger titanium nitrides.
- The niobium concentration up to 0.12 wt% in a Ti and Nb microalloyed
steel shows no influence on the precipitation temperature of nitrides,
whereas the formation temperature of niobium carbides is increased
substantially up to 0.03 wt% Nb. The nitride precipitates contain a
high concentration of titanium while carbides mostly formed of niobium.
- Titanium concentration increases the precipitation temperatures of
titanium nitrides in a Ti and Nb microalloyed steel. However, the
precipitation temperatures of both nitrides and carbides increase
significantly with Nb concentration.
The results are in good agreement with experimental data in the
literature, highlighting the suitability of primary calculation approach
to the design of new alloys and heat treatment processes of microalloyed
steels.