Suchandan K Das

Correlating microstructural features and mechanical properties with abrasion resistance of a high strength low alloy steel

A study towards the examination of the abrasive wear behaviour and other characteristics, viz. microstructure, tensile properties and hardness of a high strength low alloy steel has been carried out in order to establish a correlation amongst the parameters and to optimize the microstructural features and mechanical properties for superior wear performance. The steel was subjected to various heat treatment cycles for generating different combinations of microstructural features and mechanical and wear properties. The study suggests that, apart from hardness, ductility also plays a vital role in deciding the wear characteristics of steels. It has also been observed that an improvement in the abrasion resistance of the order of ∼50% can be achieved by subjecting the steel to suitable heat treatment cycles. Mechanical properties of the steel also change simultaneously. These features are ultimately controlled by the microstructural characteristics of the specimens. The results obtained have been supplemented through the characteristics of the worn surfaces, subsurface regions, debris and fractured surfaces. These analyses also helped to understand the operative mechanisms of material removal and failure.

Abrasive wear behaviour of zinc-aluminium alloy - 10% Al2O3 composite through factorial design of experiment

AbstractTwo body abrasive wear behaviour of a zinc-aluminium alloy - 10% Al2O3 composite was studied at different loads (1–7 N) and abrasive sizes (20–275 μm) as a function of sliding distance and compared with the matrix alloy. The wear rate of the composite and the matrix alloy has been expressed in terms of the applied load, abrasive size and sliding distance using linear factorial design approach. The study suggests that the wear rate of the alloy and composite follow the following relations:

Analytical model for erosion behaviour of impacted fly-ash particles on coal-fired boiler components

\begin{gathered} Y_{{\text{alloy}}} = 0.1334 - 0.0336x_1 + 0.0907x_2 + 0.0296x_1 x_2 + 0.0274x_2 x_3 - 0.0106x_3 x_1 \hfill \\ {\text{ }} - 0.0201x_1 x_2 x_3 \hfill \\ Y_{{\text{comp}}} = 0.0726 - 0.028x_1 + 0.062x_2 + 0.03x_3 - 0.024x_1 x_2 + 0.028x_2 x_3 - 0.016x_3 x_1 \hfill \\ {\text{ }} - 0.014x_1 x_2 x_3 \hfill \\ \end{gathered}

Thermal modelling of DC continuous casting including submould boiling heat transfer

where, x1, x2 and x3 are the coded values of sliding distance, applied load and abrasive size respectively. It has been demonstrated through the above equations that the wear rate increases with applied load and abrasive size but decreases with sliding distance. The interaction effect of the variables exhibited a mixed behaviour towards the wear of the material. It was also noted that the effect of load is less prominent for the composite than the matrix alloy while the trend reversed as far as the influence of the abrasive size is concerned.

Low Stress Abrasive Wear Behavior of a Hardfaced Steel

An attempt has been made in this study to examine the effects produced by the reinforcement of (10 wt%) SiC particles on the sliding wear behavior of a Zn-base alloy. The matrix alloy was also subjected to identical test conditions to assess the influence of the SiC dispersoid phase. The wear characteristics of the (Zn-base alloy) composite and the matrix alloy were also compared with those of a Cu-base alloy (i.e., an aluminum bronze) in order to understand the scope of exploiting the Zn-base alloy matrix/composite as a substitute material for the latter (Cu-base) alloy.It has been observed that low frictional heat generated at the lower sliding speed (0.42 m/s) enabled the Zn-base (matrix) alloy to perform better than the composite material, while the Cu-base alloy showed intermediate wear resistance. On the contrary, the trend changed at a higher sliding speed (4.62 m/s) when high frictional heating caused the wear behavior of the Cu-base alloy to be superior to that of the Zn-base (matrix) alloy. The composite in this case performed better than the matrix alloy.The wear behavior of the specimens has been explained in terms of factors like microcracking tendency and thermal stability introduced by the SiC dispersoid phase and lubricating, load bearing, and low melting characteristics of microconstituents like α and η in the (Zn-base) alloy system and the thermal stability of the Cu-base alloy. It seems that the predominance of one set of parameters over the other actually controls the overall performance of a material. Once again, it is the test conditions that ultimately allow a particular set of factors to govern the other and influence the response of the specimens accordingly. The observed wear behavior of the samples has been substantiated further with their wear surface characteristics.

Computational modelling of thermal transport phenomena in continuous casting process based on non-orthogonal control volume approach

Fly ash particles entrained in the flue gas from boiler furnaces in coal-fired power stations can cause serious erosive wear on steel surfaces along the flow path. Such erosion can significantly reduce the operational life of the boiler components. A mathematical model embodying the mechanisms of erosion on behaviour, has been developed to predict erosion rates of coal-fired boiler components at different temperatures. Various grades of steels used in fabrication of boiler components and published data pertaining to boiler fly ash have been used for the modelling. The model incorporates high temperature tensile properties of the target metal surface at room and elevated temperatures and has been implemented in an user-interactive in-house computer code (EROSIM-1), to predict the erosion rates of various grades of steel. Predictions have been found to be in good agreement with the published data. The model is calibrated with plant and experimental data generated from a high temperature air-jet erosion-testing facility. It is hoped that the calibrated model will be useful for erosion analysis of boiler components.

Neural network modelling of flow stress and mechanical properties for hot strip rolling of TRIP steel using efficient learning algorithm

An attempt has been made to explore the possibility of using natural mineral namely sillimanite for synthesizing aluminium alloy composite through a solidification technique. The sillimanite particles were characterized in terms of X-ray, differential thermal analysis in order to examine their suitability for preparing the composite. An aluminium alloy (BS:LM6) was used as the matrix alloy. The sillimanite particles of mean size 140 μm (major axis) were used as reinforcement. The sillimanite particles were added into the matrix melt by creating a vortex with the help of a mechanical stirrer and the melt temperature was maintained between 750 and 800°C. The cast composite was characterized in terms of microstructural, mechanical and abrasive wear properties. It was noted that the sillimanite particles were reasonably uniformly distributed within the matrix and exhibited good mechanical bonding with the matrix. The strength of the composite was noted to be marginally lower than that of the base alloy but the hardness and the wear resistance of the composite were found to be significantly higher than those of the base alloy.

Monte Carlo simulation of influence of reheat temperature on austenite grain growth in C-Mn steel

The steady-state thermal problem associated with the direct-chill continuous casting of aluminium–magnesium (Al–Mg) alloy cylindrical ingots is solved by an efficient numerical simulation method which also includes secondary cooling with submould boiling heat transfer. A nonorthogonal control volume discretisation and coordinate transformation technique has been applied for solving the heat transport phenomena in a multi-domain framework which involves detrmination of the solid–liquid interface (solidification front) and evaluation of the thermal profile during continuous casting operation. Conservation equations are reformulated in differential–integral form in terms of the transformed coordinates. All the terms arising from the nonorthogonality of the control volume have been retained in the numerical solution methodology and a front tracking procedure has been applied based on an iterative solution scheme. Using theories of nucleate boiling with forced convection and film cooling, a methodology has been devised to evaluate the external boundary conditions in the submould region of the ingot. These concepts are incorporated into the numerical model to account for the secondary cooling conditions during ingot solidification and simulation results show very good agreement with the published experimental data.