Porous copper mandrels prevent uneven deformation of beryllium machining blanks. The beryllium powder is arranged around these mandrels and hot isostatically pressed to form the blanks. The mandrels are then removed by leaching

Gripshover, P. J.

Hanes, H. D.

English

NASA Technical Reports Server

June 1967
	 Brief 67-10209 
Porous Mandrels Provide Uniform Deformation in Hydrostatic Powder Metallurgy 
A program was initiated to investigate the gas-
pressure bonding process as a potential means for 
hot isostatically pressing relatively large, complex 
beryllium machining blanks from beryllium powder. 
The powder to be densified was first preformed by 
cold isostatic pressing to the desired shape. Internal 
and external cavities were initially formed by use of 
leachable solid copper mandrels, after which the part 
was gas-pressure compacted at controlled tempera-
ture, and the mandrels selectively removed by 
leaching. 
In two identical specimens pressed in this manner, 
uneven deformation was observed around the solid 
copper mandrels. Poor dimensional control and gross 
cracking were evident, causing failure of the speci-
men. It was apparent that this method of pressing 
would not succeed. 
Various types of copper powders were then pres-
sureless sintered as a means of producing porous 
mandrels. On empirical grounds, hydrogen-sintering 
parameters of 2 hours at 1600°F were chosen as 
giving greatest promise for producing the desired 
density. In actual practice, pressureless sintering for 
3 hours at 1700°F was found to give densities of 
57 to 60 percent of theoretical. The porous copper
mandrels were placed in the forming jig and the beryl-
lium powder arranged over and around them. Hot, 
isostatic pressing formed the blank and the porous 
mandrels were removed by leaching. 
Notes: 
1. In contrast to the specimen pressed around the 
solid mandrels, no cracking occurred in the pre-
form pressed around the porous mandrels. 
2. Inquiries concerning this invention may be di-
rected to: 
Technology Utilization Officer 
Marshall Space Flight Center 
Huntsville, Alabama 35812 
Reference: B67-10209 
Patent status: 
Inquiries about obtaining rights for the commercial 
use of this invention may be made to NASA, Code 
GP, Washington, D.C. 20546. 
Source: Hugh D. Hanes and Paul J. Gripshover

of Battelle Memorial Institute 
under contract to
Marshall Space Flight Center

(M-FS-1972) 
Category 03 
This document was prepared under the sponsorship of the National
	 Government assumes any liability resulting from the use of the 
Aeronautics and Space Administration. Neither the United States 	 information contained in this document, or warrants that such use 
Government nor any person acting on behalf of the United States
	 will be free from privately owned rights.
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Porous mandrels provide uniform deformation in hydrostatic powder metallurgy

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