Microstructural Characterization And Mechanical Properties Of Al-Si-Cu Alloys Processed By Cooling Slope Casting And Equal Channel Angular Pressing (ECAP).

Salleh, Mohd Shukor and Subramanian, Sivarao and Md Ali, Mohd Amran and Zakaria, Kamarul Ariffin and Mohamad kamal, Mohamad Ridzuan (2018) Microstructural Characterization And Mechanical Properties Of Al-Si-Cu Alloys Processed By Cooling Slope Casting And Equal Channel Angular Pressing (ECAP). Project Report. Universiti Teknikal Malaysia Melaka, Melaka, Malaysia. (Submitted)

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Abstract

Recent years,severe plastic defonnation (SPD) is recognized as a technique to produce an ultrafine grained (UFG) structure.There are many techniques of SPD and the most popular:and widely applied is equal channel angular pressing (ECAP) technique.In spite of that numerous study have been led ECAP process that used a dendritic billet as its feedstock.Therefore,in this research a feedstock with a non-dendritic microstructure is prefe1Ted to be used in ECAP process.This study investigates the evolution of a-Al microstructure of cooling slope casting in combination with ECAP processing.The research also focussed on to investigate the mechanical prope11ies and wear prope11ies of Al- Si- Cu alloys processed by cooling slope casting and ECAP before and after T6 heat treatment.The Al- Si- Cu alloys was cast by cooling slope casting to produce a non-dendritic billet for ECAP process.ECAP process were performed by pressing a sample through a 120 ° die via route A (aluminium sample is pressed without rotation between passes) at room temperature.The microstructure of the processed alloys was observed under optical microscope (OM) and scanning electron microscope (SEM) while the mechanical properties of the alloy were validated by using Vickers hardness test and tensile test.Pin on disc test were applied to study the wear prope11ies of the deformed alloys.The results obtained indicates that the microstructure features were improves after 2 ECAP passes as the grain size was obviously refined to 37 μm from 75 μmin cooling slope cast sample.It was also discovered that the distribution of a-Al and eutectic phases were more homogeneous for cooling slope cast combined with ECAP compared to conventional casting combined with ECAP. Besides that,the mechanical properties of the alloy were ultimately improve in ECAP sample.The hardness of the alloy processed by ECAP increased as high as 84.3 HV after two ECAP passes compared to the conventional cast alloy with value of 44.6 HV.The highest ultimate tensile strength achieved by a cooling slope cast with two ECAP passes with value of237.583 MPa while the lowest strength obtained by conventional cast sample at 105.125 MPa.It was also reveal that the wear resistance of the alloy improved after the combination of cooling slope casting and ECAP process.In T6 condition,the mechanical and wear properties were enhanced as the distribution of Si Particles were more homogeneous.

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