Higher requirements of efficiency on railroad systems have set off (among other measures) higher axle load on rails. The increase in axle loads can contribute to a series of defects on perhaps the most unappreciated component of a railroad system. Higher axle loads can lead to excessive wear, fatigue and ultimately fracture of the steel rails. Therefore to answer the challenge demanded by the increase in axle loads the development of high performance steels for rail applications is of primary importance. A research program to study the microstructural aspects of near-eutectoid steels with improved mechanical properties and wear resistance was recently completed. The new high performance rail steels were developed through a combination of advanced alloy design-thermomechanical processing-and-controlled cooling. The mechanical properties exhibited by the new steels have exceeded the AREMA requirements for this type of rail steel application. The wear resistance of the newly developed steels was evaluated and the results obtained compared to commercial rails were superior under the testing conditions used in this study. The alloy design philosophy, thermomechanical processing and properties of the new steels will be presented and discussed in this paper.

This study compares austenite grain growth and its continuous cooling transformation (CCT) behavior between selective laser melting (SLM) 4340 and conventional wrought 4340 steels. Standard dilatometry tests were used to determine the austenite decomposition behavior at different cooling rates. The analysis of the data from the controlled cooling paths was used to generate CCT diagrams for the two steels investigated in this study. Advanced microstructural characterization techniques, Scanning Electron Microscopy and Orientation Imaging Microscopy, were employed to support the CCT diagrams. Electron Backscatter Diffraction (EBSD) and a special EBSD-Image Quality characterization technique were used to assess the percentage of the microstructural components observed. Three important observations were made: (1) the hardenability of the wrought 4340 steel was higher than the SLM 4340 steel; (2) the presence of granular bainite was observed after slow cooling conditions in both steels; (3) the SLM steel exhibited finer austenite grain size distribution than the wrought steel in the temperature range studied. MTEX, a MatLab program, was used to reconstruct the prior austenite grains. The SLM steel exhibited finer austenite grain size distribution than the wrought steel in the temperature range studied.

The annealing behavior of three HSLA steels is studied using the combined techniques of EBSD-KAM and Sub-grain Method. These techniques have been successfully used to assess the annealing behavior of AK, IF and other high strength steels. Stored energy maps in the hot band, cold rolled and after annealing are constructed and analyzed. The combined usage of the Sub-grain Method and EBSD-KAM techniques are employed to calculate and compare the evolution of the stored energy and recrystallization behaviour during the annealing of Ti-bearing, Nb-bearing, and V-bearing HSLA steels. Orientation dependent stored energy distribution maps at different annealing stages are constructed and analysed. The results show that the stored energy distribution through the thickness of the samples is not uniform and is independent of the steel composition. Similarly the recrystallization behaviour is strongly related to the initial microstructural condition and particularly to the grain boundary character distribution of the steels.

In the research below, an analysis is presented that has the different prisms and pieces of masonry to the compression efforts and axial compression. In order to compare the relationship between them. The process was carried out selecting different samples of both elements. These were taken to a laboratory where the different compressive stress and axial compression tests were performed. The result of the graphs shows that the stresses found in the piece-masonry are greater than those shown by the CHOC-08 equations. It is concluded that the materials used in Honduras for the prism are oversized, so it is recommended to continue carrying out tests to validate the data of the Honduran construction code.

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