Clustering effect on high temperature tensile behaviour of vanadium microalloyed steel

In the present work, high temperature tensile behaviour of vanadium microalloyed steel has been examined under as-received, air cooled and stainless steel cylinder tube cooled conditions. The results indicated that ultimate tensile strength (UTS) of the as-received samples and samples cooled in air and in a stainless steel cylinder tube showed larger differences after testing at 450 °C where the air cooled samples displayed the highest UTS. The increased in UTS at 450 °C suggests there is interaction between dislocation and precipitate particles or solute atoms which make dislocation movement more difficult. This is due to the presence of solute atoms such as carbon and nitrogen in solid solution. Tempering steel samples at 450 °C after air cooling or accelerated air cooling indicated that increasing tempering time reduced clustering effect of V and C on UTS by the formation of VCN precipitates, as a result steel samples showed a decrease in UTS.