Publication details
Experimental and theoretical studies of bainitic creep-resisting T23 steel
| Authors | |
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| Year of publication | 2009 |
| Type | Conference abstract |
| MU Faculty or unit | |
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| Description | CALPHAD approach is a progressive tool of material engineering helping in a development of new advanced materials. Based on this approach, we can make phase diagram calculations and predictions, and simulate diffusion-controlled phase transformation, too. In a view of the application, these phase diagrams calculations play a significant role in a, i.e., prediction of thermal-induced structure changes in new materials supposed to be used for power industry. Furthermore, perhaps all structural parts of power plants are welded, so, if the operation temperature is achieving values above 500stC, the simulations of diffusion-controlled phase transformations occurring in so thermal loaded weld joints enable to predict their structure stability and then a service lifetime of all the structural part. One of those new materials supposed to be used for power industry is bainitic creep-resisting T23 steel, a modification of low-alloyed 2.25Cr-1Mo steel, containing Cr (2.25 wt.%), Mo (0.1 wt.%), C, V, Mn (each 0.2 wt.%), and B, N (each 0.006 wt.%). Moreover, T23 steel is alloyed with 1.6 wt.% of W and 0.04 wt.% of Nb. Due to addings, as-treated steel has an improved creep resistance, high elastic-plastic properties, and a good weldability. Therefore, T23 steel is said to be use for power components at operating conditions up to 600degC. Because of, considering a service lifetime of components, a necessary prediction of long-term structure, corrosion, and strength behaviour of the material, our research was focused on study of structure behaviour of T23 steel at long-term isothermal exposure at 650degC. In opposite to 100 000 hrs exposure at 600stC (maximum service temperature), the increased temperature allows to get same degraded structure of steel after already 10 000 hrs. The thermal-induced phase transformations of as-received, as-welded, and as-exposed T23 steel were predicted by using Thermo-Calc and DICTRA. At the same time, XRD analysis, light and electron microscopy, and Vickers hardness measurement were used. |