Two-step solid state welding cycle applied to carefully prepared surfaces of an unrecrystallized alloy prevents loss of parent-metal strength at weld joint of dispersion-strengthened, nickel-chromium alloy

Holko, K. H.

Moore, T. J.

English

NASA Technical Reports Server

December 1971	 Brief 71-10520 
NASA TECH BRIEF 
Lewis Research Center 
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 
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be directed to the Technology Utilization Office, NASA, Code KT, Washington, D.C. 20546. 
Solid State Welding of Dispersion-Strengthened Nickel Alloys 
The problem: 
Weld a dispersion-strengthened, nickel-chromium 
alloy without losing parent-metal strength at the weld 
joint. Fusion welding and brazing methods result in 
weidments having approximately 50% of the parent-
metal strength. Previously, solid state welds have 
proven to be weak when tested at elevated tempera-
tures (2000° F). 
The solution: 
Apply a special two-step, solid state welding cycle 
to carefully prepared surfaces of the unrecrystallized 
alloy. 
How it's done: 
Lap welds were made in a 0.062 in. thick uncrystal-
lized Ni-20Cr-2TH0 2 sheet obtained from the manu-
facturer. (Normally, the sheet is recrystallized before 
shipment.) 
The surfaces to be welded were sanded with 600-
grit paper, electropolished, and cleaned with trichlo-
rotrifluoroethane. The specimens were stored in this 
degreasing agent until ready for welding. The pre-
pared specimens were welded in a vacuum hot-press 
welder evacuated to a pressure of 2x 10- 5 torr. The 
parameters of the two-step welding cycle were: (1) 
1300° F, 30,000 psi, 1 hr; and (2) 2175° F, 2000 psi, 
2 hr. All welds were postheated at 2300° F for one 
hour to achieve stress relief and ensure that recrys-
tallization was complete. 
In both short-time shear and over-100-hours creep-
rupture tests at 2000° F, the weld joint strength was 
the same as the strength of the parent material. 
Notes: 
1. This solid state welding method may be applied 
to any alloy that undergoes recrystallization upon
heating. When recrystallization occurs, the origi-
nal weld interface is removed by grain growth 
across it. 
The method should be applicable, with modifica-
tations, to the dispersion-strengthened nickel alloys 
Ni-Th02, Ni-Cr-Th0 2 , Ni-Mo-Th0 2, and 
Ni-Cr-Al-Th02. 
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-6493 (N71-34470), Enhanced 
Diffusion Welding of TD-NiCr Sheet 
4. Technical questions may be directed to: 
Technology Utilization Officer 
Lewis Research Center 
21000 Brookpark Road 
Cleveland, Ohio 44135 
Reference: B71-10520 
Patent status: 
Inquiries about obtaining rights for the commer-
cial use of this invention may be made to: 
Patent Counsel 
Mail Code 500-311 
Lewis Research Center 
21000 Brookpark Road 
Cleveland, Ohio 44135 
Source: K. H. Holko and T. J. Moore

Lewis Research Center

(LEW-1 1388)

Category 08 
This document 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 owned .rights.
https://ntrs.nasa.gov/search.jsp?R=19710000513 2020-03-17T02:26:04+00:00Z


Solid state welding of dispersion-strengthened nickel alloys

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