Executive Summary : | Tool steels of category AISI H13 with contents of Chromium, Molybdenum and Vanadium exhibits excellent combination of hardness, strength and toughness. Consequently, the material finds potential applications in forging, extrusion, casting dies etc. which are usually having complex geometries. The project aims to enhance the mechanical performance of this material further by surface laser cladding. It is noteworthy that such a surface engineering process imposes varying cooling rates throughout the thickness of the clad region. This is expected to significantly evolve the microstructure, texture and phase structure of the material along with imposing nominal compositional gradient. Accordingly, the related mechanical behaviour of the will also modify. Several studies by various scientific communities do reveal performance improvement in laser cladded steels. However, systematic attempt to establish the structure-property correlation throughout the clad depth has not been made, so far. This piece of research aims to examine the microstructural and property gradation as a function of the clad layer thickness, heat affected zone, interface as well as the substrate material. Microstructure will be thoroughly characterized using optical and scanning electron microscopy, X-ray diffraction etc. Subsequently, variation in the mechanical properties throughout the clad thickness and at the different zones will be characterized. Initially, wear and scratch resistance of the cladded surface with increasing depth will be done progressively and will be compared with the base metal. Next, the localized properties will be evaluated by implementing depth sensing indentation technique at different thickness. The global properties will be characterized by pursuing tension and compression tests on specimens extracted from different regions of the clad region, HAZ, interface and base metal. Correspondingly, the variation in elastic modulus, hardness, yield and ultimate strengths, ductility, toughness etc. will be determined at different zones. Most importantly these tests will be associated with in-situ digital image correlation thereby screening the strain distribution during the tensile and compression tests. The variation in the strain with thickness are appreciated by the color coded movies. Furthermore, considering the service requirements, in-situ corrosion tensile tests will be done on the specially extracted specimens. This will assess the corrosion resistance of the surface laser cladded tool steel upon simultaneous application of load. Overall, the effect of microstructural variation with clad layer thickness, interface and substrate on the corrosion and mechanical properties can be extrapolated accurately. A structure-property correlation can therein be well established. The outcome of the project will be immensely beneficial in improving the mechanical properties and performance of tools made of AISI H13 alloy by modifying it with surface laser cladding. |