Papers by Keyword: Low Temperature Heat Treatment

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Authors: Martin Sondel, Jaroslav Koukal, David Schwarz, Drahomir Schwarz
Abstract: Development of new steels with higher creep resistance must be based on detailed knowledge of strengthening and degradation processes, structural stability at high temperature exposure and their welding. This paper is concerned with the real weld joint hardness and microstructure of progressive low alloy creep resistance T24 steel. These steel is widely used in many power-plant constructions all over the Europe. Welding the T24 steels components is one of the most important technological procedures. The aim of the performed investigation is to evaluate the hardness and microstructure in the heat affected zone (HAZ) and the weld metal. Results of the secondary hardening in the real weld joints after low temperature post weld heat treatment (460°C/48h) and without post weld heat treatment at service temperature are described in this paper. Obtained results are compared to the hardness values of the weld joint post weld heat treated at recommended temperature (740°C). The microstructure of the real weld joints was analysed by transmission electron microscopy (TEM) in order to identify minority phases - MX nanoparticles and/or coarse (M23C6) particles. Secondary hardening of the not heat treated and low temperature heat treated T24 weld joint was proved.
Authors: Osman Ertörer, Troy D. Topping, Ying Li, Yong Hao Zhao, Wes Moss, Enrique J. Lavernia
Abstract: The room temperature tensile behavior of commercially pure titanium (CP-Ti), cryomilled under different conditions and forged quasi-isostatically into bulk form, was studied in detail. The results demonstrate that the ductility of cryomilled titanium can be improved, and that the mechanical properties can be tailored using three specific strategies: the use of liquid argon as cryomilling media, introduction of coarse grained regions, and low temperature heat treatment. Cryomilling in a liquid argon environment, which differs from the widely used nitrogen cryogenic environment, was found to have a particularly strong influence on ductility, as it prevents nitrogen embrittlement. The contribution of coarse grains and heat treatment to ductility are also introduced and discussed using a comparative approach.
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