Publication details
CARBON AND NITROGEN REDISTRIBUTION IN WELD JOINTS OF HEAT RESISTANT STEELS
| Authors | |
|---|---|
| Year of publication | 2005 |
| Type | Article in Proceedings |
| Conference | 1-st International Conference Super-High Strenght Steels |
| MU Faculty or unit | |
| Citation | |
| Field | Physical chemistry and theoretical chemistry |
| Keywords | weldment;phase;DICTRA;CALPHAD;P91;carbonitride |
| Description | The present contribution deals with the theoretical modelling of the kinetics of the development of chemical composition and phase profiles of heterogeneous laboratory weld joints of heat resistant steels from the point of view of their long-term stability. The T25 ( 6 CrMoV 8-3-2) heat-resistant ferritic steel currently being developed and the advanced P91 (X10CrMoVNb 10-1) chromium steel, both steels after ion nitriding, homogenisation at 1050şC and weld joining were the subject of study. The basic compositions of materials were approximated as the Fe-Cr-Ni-Mo-V-C-N system. The long-term annealing of the T25+0.1129wt%N | P91+(0.8-0.064wt)N weld joints were simulated at 600şC and 900şC. The simulated results were compared with experimental carbon profile observations. The phase diagrams of the investigated materials were calculated using the CALPHAD approach [1] and applying the STEEL thermodynamic database [2]. The activities of carbon, nitrogen, and other elements were calculated by the same method. The CALPHAD approach complemented with an appropriate diffusion model [3] given in the DICTRA code enabled simulating the phase and element profile evolutions inside the diffusion-affected zone of weld joint. The DIF kinetic database [4] was used to describe the diffusion. In the simulation the coexistence of different phases (carbides, carbonitrides,) was assumed. |
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