Manufacturing Technology Today

R. Chandramouli ¹, D. Shanmugasundaram ¹, T. K. Kandavel ¹, T. Ashok Kumar ¹

Affiliations
1 School of Mechanical Engineering, Shanmugha Arts, Science, Technology & Research Academy (SASTRA), Deemed University, Thanjavur-613402, Tamil Nadu, IN

Abstract

The present investigation is focused on the densification behaviour of sintered aluminium alloys of AI-Cu-C with additions of magnesium powder in varying quantities. The influence of normalizing heat treatment on deformation behaviour has also been investigated. Magnesium powder (-150 μ) has been added in varying percentage to Al-Cu-C alloy phase in order to study the influence of Mg on the deformation, densification and metallurgical structure of the P/M Al alloys mentioned above. Elemental powders of Al, Mg, C &Cu were mixed thoroughly in a pot mill for 8 hrs and the powder blends were compacted In to cylindrical shaped preforms of aspect ratio 0.6, applying a pressure of 125 MPa. in hydraulic press. After sintering at 550 °C for 90 minutes cold upsetting tests were carried out on the preforms. Another set of cold upsetting tests were undertaken after subjecting the sintered preforms to normalizing heat treatment at 500 °C. Density and dimensional measurements were carried out after each step of deformations. Axial upsetting was continued upto the point of appearance of fine surface cracks on the bulged surfaces. The results of the investigations revealed that the normalizing heat treatment notably Influenced the flow stress of the alloys. However It has marginal effects on densifications. Addition of higher percentage of Mg to Al-1% C-1% Cu alloy has also affected the deformation as well as densification behavior. Increasing the Mg content has lead to reduced levels of plastic deformation as well as densification. The combination o f addition of Mg and heat treatment has Influenced the flow stress because adding higher Mg demands higher flow stresses during axial upsetting. Normalizing of the alloys with Mg content enhances the resistance to deformation and densification. Addition of Mg to the alloy AI-C-Cu has reversed the response of the material during cold upsetting. The microstructure of the alloys reveals the presence of numerous rounded and small pores with in the grains and along the grain boundary. It also reveals subtle differences due to normalizing heat treatment.

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R. Chandramouli ¹, D. Shanmugasundaram ¹, T. K. Kandavel ¹, T. Ashok Kumar ¹

Affiliations
1 School of Mechanical Engineering, Shanmugha Arts, Science, Technology & Research Academy (SASTRA), Deemed University, Thanjavur-613402, Tamil Nadu, IN

Abstract

Aluminium based MMC's with SiC reinforcement are known to find numerous applications in the aerospace and automotive industry In view of high strength to weight ratio and stiffness. Alloys with Cu, Zn, Mg added to Al are also high strength light weight materials widely used in aerospace industry for application such as landing gears, fasteners etc,. In the present investigation atomized iron powder has been added In varying percentages to Al-Cu-C alloy phase in order to study the influence of Fe on deformation, densification and metallurgical structure of sintered Al alloys. Elemental powders of Al, Fe, C & C u were mixed thoroughly In a pot mill for 8 hrs and the powder blends were compacted in to cylindrical shaped performs of aspect ratio 0.6. After sintering at 550°C for 90 minutes cold upsetting test were carried out in the performs. Another set of cold upsetting test were undertaken after subjecting the sintered preforms to normalizing heat treatment at 500°C. Density and dimensional measurements were carried out after each step of deformation level. The results of the investigations revealed that the normalizing heat treatment notably influenced the flow stress of the alloys. However it has only marginal effects on densification. Addition of Fe to AI-1% C-1%Cu alloys in the proportion of 0.1, 0.2, and 0.3 has also affected the deformation as well as densification behavior. Increasing the Fe content has lead to reduced levels of plastic deformation as well as densification. The combined effects of addition of Fe and heat treatment have affected the flow stress. Adding higher Fe contents demands higher flow stress. Normalizing of the alloys with Fe contents enhances the resistance to deformation and densification. The stress-strain behavior in all the cases of the alloys is characterized by linearity. The peak density levels achieved after the forging not exceed 96% of theoretical density. The microstructure of the alloys reveals the presence of numerous rounded and small pores within the grains and along the grain boundary.

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