Title page for ETD etd-042811-150151

Document Type dissertation

Author Name Saleem, Muhammad Qaiser

URN etd-042811-150151

Title Helium Assisted Sand Casting of Aluminum Alloys

Degree PhD

Department Manufacturing Engineering

Advisors
Prof. Makhlouf M. Makhlouf, Advisor
Prof. Richrad D. Sission Jr., Committee Member
Prof. Diran Apelian, Committee Member
Prof. Yiming (Kevin) Rong, Committee Member
Mr. Bob Logan, Committee Member

Keywords
thermal conductivity
helium
Sand casting

Date of Presentation/Defense 2011-04-25

Availability unrestricted

Abstract
Sand casting is the most widely used casting process for both ferrous and non-ferrous alloys; however, the process is marred by large grain size structures and long solidification times. The coarser microstructure has a negative effect on the mechanical properties of the cast components and the long processing time affects the overall productivity of the process. The research reported herein addresses these problems for aluminum sand castings by enhancing the rate of heat extraction from the casting by replacing air, which is typically present in the pores of the sand mold and has a relatively low thermal conductivity by helium which has a thermal conductivity that is at least five times that of air in the temperature range of interest. The effect of (1) the flow rate of helium, (2) the way in which it is introduced into the mold, and (3) the mold design on (a) the average grain size, (b) the secondary dendrite arm spacing, and (c) the room temperature tensile properties of castings is investigated and compared to their counterparts produced in a typical sand casting process. In addition, a cost analysis of the helium-assisted sand casting process is performed and an optimum set of parameters are identified. It is found that when the helium-assisted sand casting process is performed with close to the optimum parameters it produces castings that exhibit a 22 percent increase in ultimate tensile strength and a 34 percent increase in yield strength with no significant loss of ductility, no degradation in the quality of the as-cast surfaces, and no significant increase in the overall cost.

Files
M_Qaiser_Saleem.pdf

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Document Type	dissertation
Author Name	Saleem, Muhammad Qaiser
URN	etd-042811-150151
Title	Helium Assisted Sand Casting of Aluminum Alloys
Degree	PhD
Department	Manufacturing Engineering
Advisors	Prof. Makhlouf M. Makhlouf, Advisor Prof. Richrad D. Sission Jr., Committee Member Prof. Diran Apelian, Committee Member Prof. Yiming (Kevin) Rong, Committee Member Mr. Bob Logan, Committee Member
Keywords	thermal conductivity helium Sand casting
Date of Presentation/Defense	2011-04-25
Availability	unrestricted
Abstract Sand casting is the most widely used casting process for both ferrous and non-ferrous alloys; however, the process is marred by large grain size structures and long solidification times. The coarser microstructure has a negative effect on the mechanical properties of the cast components and the long processing time affects the overall productivity of the process. The research reported herein addresses these problems for aluminum sand castings by enhancing the rate of heat extraction from the casting by replacing air, which is typically present in the pores of the sand mold and has a relatively low thermal conductivity by helium which has a thermal conductivity that is at least five times that of air in the temperature range of interest. The effect of (1) the flow rate of helium, (2) the way in which it is introduced into the mold, and (3) the mold design on (a) the average grain size, (b) the secondary dendrite arm spacing, and (c) the room temperature tensile properties of castings is investigated and compared to their counterparts produced in a typical sand casting process. In addition, a cost analysis of the helium-assisted sand casting process is performed and an optimum set of parameters are identified. It is found that when the helium-assisted sand casting process is performed with close to the optimum parameters it produces castings that exhibit a 22 percent increase in ultimate tensile strength and a 34 percent increase in yield strength with no significant loss of ductility, no degradation in the quality of the as-cast surfaces, and no significant increase in the overall cost.
Files	M_Qaiser_Saleem.pdf