Addition Of Oxide Particles Research Articles

Investigation of cold cracking resistance of HSLA 950A steel by taguchi optimization technique

Cold cracking is one of the major issues during welding High Strength Low Alloy (HSLA) 950A steel. The aim of the present research work is to optimize preheating temperature, the addition of oxide particles, and heat input using the Taguchi design of experiments for bead on plate, especially on the improved impact strength of weld metal. The experiments are carried out at three levels of mentioned parameters and Charpy impact strength is considered as a response. L27 orthogonal array is selected for experimentation in the present investigation using three parameters. An addition of vanadium oxide (V2O5) has acted as a nucleation site for acicular ferrite and enhanced the cold cracking resistance of investigated steel. The experimental results suggested that the impact strength of weldment is strongly influenced by pre-heating temperature (74.5%) and less influenced by oxide particle concentration (12.7%), and heat input (12.2%). Microstructure at HAZ revealed the presence of a small proportion of acicular ferrite of Widmanstatten morphology and upper bainite near weldment causes the reason for enhancement in cold cracking resistance. Fractographic examination revealed the presence of both ductile and brittle fracture modes, which attributed to higher and lower impact strength of weld joint respectively.

Effect of Heat Treatment on Microstructure and Tensile Properties of A356/V2O5 Insitu Composites

A 356 alloy reinforced with insitu V2O5 particles by using stir casting technique. The composites were produced by the addition of oxide particles in different weight percentage. The effect of oxide powder addition on microstructure and mechanical properties of produced composites were investigated. The effect of heat treatment on microstructure and mechanical properties were investigated by optical microscope, Microhardness tester and tension test. A significant improvement in hardness and tensile strength was revealed in the produced composite as compared to the base alloy. With the addition of oxide particles, the shape and size of eutectic Si changed which in turn affects the properties. It was observed that 2h solutionizing followed by the artificial aging was sufficient to make the structure homogenize and to produce the hardening precipitates. The improvement in the mechanical properties has been observed due to the age hardening precipitates in addition with refinement of insitu V2O5 particles.

Platinum Ceramic Composites as new Electrode Materials: Fabrication, Sintering, Microstructures and Properties

The economical application of precious metals as electrode materials is an important economic and ecological task. Different platinum composites with 14 vol.% ceramic dispersoids were fabricated. The sintering behaviour and microstructure development was studied in the temperature range between 1000°C and 1760°C. Significant differences were found with respect to the sintering activity and the particle size distribution. Spark erosion tests revealed that the erosion resistance of platinum is degraded by the addition of oxide particles. A new model is proposed to explain the observed erosion behaviour.