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Research aimed at enhancing the surface properties of carbon steels by incorporating fine silicon carbide particulates has had limited success because the dissolution of the ceramic occurred. This research considers a method of reducing SiC dissolution by generating a high Fe–Si liquid which protects the ceramic. Three particulate groups were investigated, (1) ∼ 5 µm SiC, (2) ∼45 µm Si +∼ 5 µm SiC, and (3) ∼45 µm Si, all incorporated into a microalloyed steel using a tungsten inert gas process. Detailed microhardness of the melt zones together with microstructural analysis showed that the addition of Si resulted in a cracked hard layer containing SiC. However, in Specimen 1, a thicker, hardcrack-free layer resulted from the microstructure developed by the dissolution of SiC.

Effect of an optimized multi-step heat treatment routine on conventional (machining from wrought bar stock) and alternate manufacturing routes (hot forging and cold rotary forging) for producing flat cylindrical-shaped machine drive components from 18CrNiMo7-6 steel was investigated. The microstructure and mechanical properties of the final component manufactured using these three different routes were analyzed using optical microscopy, electron backscatter diffraction (EBSD), hardness testing, electro-thermal mechanical testing (ETMT), and rotary bending fatigue testing (RBFT) before and after implementing the multi-step heat treatment. It was found that the multi-step heat treatment transformed the as-received microstructure into the tempered martensitic microstructure, improving hardness, tensile, and fatigue properties. The heat treatment produced desired properties for the components manufactured by all three different routes. However the cold rotary forging, which is the most material utilizing route over the others, benefited the most from the optimized heat treatment.

The effect of coiling temperature on the microstructure and mechanical properties of a Nb-V microalloyed steel was investigated. Controlled rolling followed by accelerated cooling and coiling was simulated by means of both, uniaxial compression, using a quenching and deformation dilatometer, and torsion. Specimens were reheated at 1250º for 5-10 min, then deformed at 1150°C, =0.3, and subsequently at 900°C, =0.4, followed by rapid cooling to a temperature between 450 and 700°C where coiling was simulated by holding the specimen for one hour at the selected temperature followed by a slow cooling to room temperature. Mechanical characterization was performed by means of hardness measurements and tensile tests, using tubular specimens machined from the torsion samples. It was found that decreasing the coiling temperature the ferrite-pearlite microstructure changed to ferrite-bainite, with a hardness peak reached for coiling at 600°C-650°C.

Environmental conditions, testing variables, and material properties significantly influence the sliding wear behaviour of all tribosystems. Such parameters affect the mechanism of wear occurring, govern how the wear scar will be categorised, and control whether transitions occur throughout the test. The present study investigated this through sliding wear tests of AISI 4330, 15-5PH, and heat treated cast iron in the dry and NaCl regime. Loads of 2kg, 4kg, and 6kg were applied to the cast iron pin in both regimes, with the volume loss results, wear scar morphology, and microstructural evolution analysed. It was found that the AISI 4330 and 15-5PH discs produced higher volume losses in the dry regime than the NaCl regime, indicating the solution gave a beneficial effect rather than a detrimental effect versus the dry tribosystem. Beneficial oxidative wear allowed for AISI 4330 to lose less than 15-5PH in the dry regime, with their respective cast iron pins following the same result. Microstructurally, the 15-5PH wear scar cross-sections exhibited a mechanically mixed surface layer of refined material mixed with oxides, above a layer of grains distorted in the direction of sliding. This highlighted the