Powder metallurgy-based metal matrix composites (MMCs) are widely chosen and used for the development of components in the fields spanning aerospace, automotive and even electronic components. Engineered MMCs are known to offer a high strength-to-weight (σ/ρ) ratio. In this research study, we synthesized cylindrical sintered samples of a ceramic particle-reinforced aluminum metal matrix using the technique of powder metallurgy. The samples for the purpose of testing, examination and analysis were made by mixing aluminum powder with powders of silicon carbide and aluminum oxide or alumina. Four varieties of aluminum composite were synthesized for a different volume percent of the ceramic particle reinforcement. The hybrid composite contained 2 vol.% and 7 vol.% of silicon carbide and 3 vol.% and 8 vol.% of alumina with aluminum as the chosen metal matrix. Homogeneous mixtures of the chosen powders were prepared using conventional ball milling. The homogeneous powder mixture was then cold compacted and subsequently sintered in a tubular furnace in an atmosphere of argon gas. Five different sintering conditions (combinations of temperature and sintering time) were chosen for the purpose of this study. The density and hardness of each sintered specimen were carefully evaluated. Cold compression tests were carried out for the purpose of determining the compressive strength of the engineered MMC. The sintered density and hardness of the aluminum MMCs varied with the addition of ceramic particle reinforcements. An increase in the volume fraction of the alumina particles to the Al/SiC mixture reduced the density, hardness and compressive strength. The sintering condition was optimized for the aluminum MMCs based on the hardness, densification parameter and cold compressive strength. The proposed powder metallurgy-based route for the fabrication of the aluminum matrix composite revealed a noticeable improvement in the physical and mechanical properties when compared one-on-one with commercially pure aluminum.

This paper investigates the use of shop-floor ferrous scrap that contains iron ore as a raw material for the purpose of making steel products through an in situ carbothermic reduction. The technique of powder metallurgy (PM) was used for the purpose of studying reduction followed by densification during sintering. Two sources of iron oxide—ferrous grinding-sludge powder and iron ore—and three sources of the carbonaceous material—graphite, charcoal, and carbon black—were considered. The carbonaceous material was added to the iron oxide after calculating the stoichiometric carbon requirement for facilitating both direct reduction and direct–indirect reduction. This involves a simultaneous change in weight and volume. During sintering, an in situ reduction of the iron oxide takes place that often results in severe volumetric changes. The test results revealed the degree of reduction (DOR) and degree of densification (DOD) of the grinding sludge (GS) to be 15% and 45% higher, respectively, than that of iron ore (IO). This is essentially due to the presence of distinct iron-oxide phases coupled with a greater amenability to the occurrence of carbothermic reduction. Indirect reduction also took place and contributed to improving the degree of reduction (DOR) and degree of densification (DOD) of the final products. Overall, the shape stability of the sintered grinding-sludge (GS) powder was found to be optimized when parameter settings of graphite (from 25% in excess to 50% in excess) were added, a compaction pressure of 1050 MPa was applied, and a sintering temperature of 1200 °C was employed. Hence, ferrous scrap can be chosen as direct reduced iron for the manufacture of steel and can also be used for cost-efficient and eco-friendly structural components with a marginal compromise on both the purity and strength of the ferrous products.

Enormous amount of scrap is generated on the shopfloor during manufacturing. Energy needed to melt increasing quantities of scrap will be ever increasing, and so will be the loss of metal during melting. Hence, conversion of scrap directly into marketable products by solid state processing methods is economical due to a lower energy requirement and a greater yield compared to the melting route. This makes the process more environmentally friendly. However, not all materials can be recycled in a solid state, with equal ease. One therefore needs to quantitatively assess the recyclability of a given kind of scrap. In the present work, a procedure to assess the recyclability of finely divided ferrous metallic scrap generated on the shopfloor is demonstrated. Recyclability includes material and the process used for recycling. For instance, a given material might be more recyclable using one process compared to the other. In the present study, the potential of powder technology (powder metallurgy (PM) and metal injection molding (MIM) based processes are compared for solid-state conversion of scrap directly into usable products. Grinding sludge collected in the shopfloor was pulverized and used as raw material. Properties of sintered parts were found to be significantly better due to in-situ reduction and densification during sintering. A quantitative measure of recyclability, namely, the Recyclability Index (RI) was defined to compare the manufacturability of different products. Recycled ferrous parts manufactured by PM route are found to have a greater RI (superior recyclability) than those manufactured by the MIM route. Complex reduction and sintering mechanisms in MIM parts, particularly, the kinetics of diffusion and volumetric shrinkage, limit suitability of MIM for recycling. In contrast, few industrial parts were developed and manufactured by conventional PM based approach to demonstrate the suitability of this novel recycling process especially for manufacture of porous parts.

Industrial components are far too complex in shape and far too large in size compared to the laboratory scale test samples used to establish failure criteria like the forming limit diagram (FLD). These have been traditionally used to predict failure, but are found to often make wrong predictions due to their sensitivity to strain path, and forming conditions like temperature. The Strain Nonuniformity Index (SNI), a single parameter determined from the spatial strain distribution, may be used to predict failure and identify locations of failure or even imminent failure. This is possible regardless of temperature or even the method of forming (cold forming, hot forming, superplastic forming etc.). The paper presents a few results demonstrating successful applications of this novel SNI based technique.

The Strain Nonuniformity Index (SNI) was introduced as a strain distribution based failure criterion about 10 years ago and its application to prediction of failure in industrial sheet metal components was demonstrated in the previous Conferences. Quantitatively, the SNI represents the rate of change of spatial strain gradient. This means that higher the SNI, sharper the neck, and hence greater is the likelihood of failure. It is immaterial as to how the neck / strain gradient came into existence, and failure is linked with the threshold value of this quantity, beyond which failure could be expected. Since phenomenological parameters are not linked with the process of establishing a threshold SNI, it does not seriously matter whether it was aluminium that was formed or whether it was steel, it does not very much matter if it was hot forming or cold forming. The present paper describes the methodology of estimating the threshold SNI for each of the numerous critical planes in the deforming sheet metal component. Interestingly, the relationship between SNI of major strain and SNI of the thickness strain was found to lie in a narrow band for a diverse set of materials. This therefore helps in finding the critical planes on which the SNI at a given punch travel has crossed the threshold value and failure locations so determined have correlated well with the shopfloor predictions as presented earlier.