Heat treatment process involves heating products to a temperature above the solidus, and subsequently applying pressure at a temperature below the solidus. Technique can be modified to one step process involving simultaneous application if both high pressure and heat. Process is not limited to cobalt-base alloys

Ashbrook, R. L.

Freche, J. C.

Waters, W. J.

English

NASA Technical Reports Server

December 1971	 Brief 71-10489 
NASA TECH BRIEF 
Lewis Research Center
	
-4 
NASA Tech Briefs announce new technology derived from the U.S. space program. They are issued to encourage 
commercial application. Tech Briefs are available on a subscription basis from the National Technical Information 
Service, Springfield,' Virginia 22151. Requests for individual copies or questions relating to the Tech Brief program may 
be directed to the Technology Utilization Office, NASA, Code KT, Washington, D.C. 20546. 
High-Temperature Strength of Prealloyed-Powder Products 
Increased by Heat/Pressure Treatment 
The high-temperature strength of products formed 
from prealloyed powders can be increased by a new 
process involving heat treatment above the solidus 
temperature (that temperature at which the material 
first begins to melt) followed by the application of 
pressure at a temperature below the solidus point. 
Presently, prealloyed-powder techniques are used 
to increase the strength of superalloys at tempera-
tures up to 1500° F. At higher temperatures, however, 
the strength of prealloyed-powder products decreases 
markedly compared to that of cast-alloy products. 
Prealloyed-powder techniques yield products with a 
very fine grain size, ar.d grain growth is required 
for increased high-temperature strength. Due to the 
complex nature of many superalloys, very high heat-
treatment temperatures are needed to achieve grain 
growth. In many cases, adequate grain size cannot 
be achieved by conventional heat-treatments below 
the solidus temperature. 
A novel, two-step heat treatment, used on products 
formed from HS-31 prealloyed powder, overcomes this 
difficulty. The treatment involves heating the products 
to a temperature above the solidus (above about 
2340° F, in the case of HS-31), and subsequently 
applying pressure at a temperature below the solidus. 
Significant grain growth is achieved during the initial 
step of heat treatment at 2450° F, but structural 
integrity is lost because of minor phase melting and 
void formation. The voids are closed and structural 
integrity is restored by secondary treatment in an 
autoclave, at 30 ksi and 2200° F. Life-to-rupture at 
1800° F and 13 ksi is increased to 20 hours by the 
heat/pressure treatment, as compared to less than 
one hour for the as-extruded powder product and 
approximately ten hours for castalloy product.
This result suggests that the high-temperature 
properties of other p real loyed-powder products could 
be improved by heat-treatment above the solidus 
temperature, followed by the application of pres-
sure below the solidus temperature. The technique 
can be modified to a one-step process involving the 
simultaneous application of both high pressure and 
heat. Also, the technique is not limited to cobalt-base 
alloys. 
Notes: 
1. Related information is contained in NASA Tech 
Brief 69-10293. 
2. The following documentation may be obtained 
from: 
National Technical Information Service 
Springfield, Virginia 22151 
Single document price $3.00 
(or microfiche $0.95) 
Reference: 
NASA TN-D-6072 (N71-10326), Evaluation 
of a Cobalt-Base Alloy, HS-31, Made by 
Extrusion of Prealloyed Powders 
Technical questions may be directed to: 
Technology Utilization Officer 
Lewis Research Center 
21000 Brookpark Road 
Cleveland, Ohio 44135 
Reference: B71-10489 
Patent status: 
This invention is owned by NASA, and a patent 
application has been filed. Royalty-free nonexclusive 
licenses for its commercial use will be granted by 
Amok	 (continued overleaf) 
This documetct was prepared under the sponsorship of the National 
Aeronautics and Space Administration. Neither the United States 
Government nor any person acting on behalf of the United States
Government assumes any liability resulting from the use of the 
information contained in this document, or warrants that such use 
will be free from privately ownedrights.
https://ntrs.nasa.gov/search.jsp?R=19710000486 2020-03-17T02:26:36+00:00Z
NASA. Inquiries concerning license rights should be 
made to: 
Patent Counsel 
Lewis Research Center 
21000 Brookpark Road 
Cleveland, Ohio 44135 
Source: J. C. Freche. R. L. Ashbrook, 
and W. J. Waters
Lewis Research Center 
(LEW-1 1229) 
Brief 7 1-10489	 Category 04


High-temperature strength of prealloyed-powder products increased by heat/pressure treatment

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