Microstructural Characteristics and Hardness Property of Laser Cladded Ti and TiB2 Nanocomposites on Steel Rail

摘要

The laser cladding experiment was carried out on a two-powder loading hub laser machine at the Center for Scientific Innovation and Research, Pretoria, South Africa. Nanocomposites of Titanium and Titanium diboride was at ratio loaded and cladded on carbon steel surface. Metallurgical characterization of microscopic and macroscopic view was executed. The X-ray diffraction was taken with the PW1710 Philips diffractometer. XRD results of TiB2 rich samples reveals peak phase of cubic Titanium diboride, hexagonal Titanium, cubic alpha-Iron, tetragonal Iron 2 boride and hexagonal Titanium diboride. XRD of even mix sample revealed clad phases of hexagonal Titanium and orthorhombic Titanium diboride. XRD of Ti rich clad revealed phases of cubic gamma-Iron-austenite, hexagonal Titanium, hexagonal titanium diboride, cubic Khamrabaevite and hexagonal alpha-Titanium phases. Sample 3 showed good XRD phases that influenced the property of the composites. The working parameters of laser power were from 1250 W to 1500 W and scanning speed of 1.0 to 1.2. m/min. The analysis showed a microhardness response range of 781 HV to 1254 HV0.5.Interesting phases and structures have been seen in the microstructures of the admixed powders. Pores and colouration pigments are vital factors influencing the properties of the microstructures. Properties of each powder has been used to form new properties of the admixed powders which has significant effects on the final microstructures of the composites. The homogeneous distribution of the reinforcements in the microstructures of the composites can be linked to the optimized parameters which in turn also enhance the mechanical properties of the composites.