Microstructural changes with selected extrusion variables in plastic deformation of complex-shaped lead alloy

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Microstructural changes with selected extrusion variables in plastic deformation of complex-shaped lead alloy

Joseph S. Ajiboye, Babatunde Idirisu

Department of Mechanical Engineering, University of Lagos, Lagos, Nigeria.

DOI:

https://doi.org/10.7494/cmms.2009.2.0237

Abstract:

This paper investigates the effects of changing die land length and web to flange ratio on the pressure and surface structures of cold plastic deformation of a triangular-, T- and L-shaped lead alloy. There is a dearth of knowledge on the influence of die land length and web to flange ratio on microstructures of extrudates and as a result the impact of these parameters has not been fully understood in die design. The work, which is purely experimental model, was carried out on a 600KN Denison Universal hydraulic testing machine. The test specimens were extruded into triangular, T- and Lshaped sections from initially circular billets at varying die land length and web to flange ratio. A forward extrusion rig is designed and manufactured for the purpose of experimental investigation. The experimental results, for all the geometries investigated, showed that extrusion pressure, product quality and straightness increases with increasing die land length. The extruded sections were examined by optical metallurgical microscope (OMM) and the effects of die land length is seen to indicate obvious changes in grain morphology from initially coarse grains at 2.5mm die land length to very fine grains structure at die land length of 12.5 mm in the extrusion of triangular section. Hence, the microstructure changes observed shows that increasing die land length leads to profound refinement of grain and inclusions in lead alloy. For increasing web to flange ratio in the extrusion of L- and T-shaped lead alloy, there is increasing fairly uniform and finegrain structure. However, there seem to be better grain refinement in T-shaped section than that of L-shaped section for the same web to flange ratio, this is probably due to geometrical differences.

Cite as:

Ajiboye, J., Idirisu, B., (2009). Microstructural changes with selected extrusion variables in plastic deformation of complex-shaped lead alloy. Computer Methods in Materials Science, 9(2), 241 – 248. https://doi.org/10.7494/cmms.2009.2.0237

Article (PDF):

Keywords:

Die land, Extrusion pressure, Triangular- and l-shaped, Grain refinement, Lead alloy, Microstructure

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