TECHNICAL REPORT 52-313, PART 1
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BRAZING TITANIUM TO TITANIUM AND TOMILD AND STAINLESS STEELS
W. J. LEWISP. S. RIEI'PEL
C. B. VOLDRICH
BATTELLE MEMORIAL INSTITUTE
WRIGHT AIR DEVELOPMENT CENTER
Statement AApproved for Public Release
When Government drawings, specifications, or other data are usedfor any purpose other than in connection with a definitely related Govern-ment procurement operation, the United States Government thereby in-cursnoresponsibility nor any obligation whatsoever; and the fact thatthe Government may have formulated, furnished, or in any way suppliedthe said drawings, specifications, or other data, is not to be regardedby implication or otherwise as in any manner licensing the holder orany other person or corporation,or conveying any rights or permissionto manufacture, use, or sell any patented invention that may in anywaybe related thereto.
The information furnished herewith is made available for studyupon the understanding that the Government's proprietary interests inand relating thereto shall not be impaired. It is desired that the JudgeAdvocate (WCI), Wright Air Development Center, Wright-PattersonAir Force Base, Ohio, be promptly notified of any apparent conflict be-tween the Government's proprietary interests and those of others.
.WADC TECHNICAL REPORT 52-313, PART 1
BRAZING TITANIUM TO TITANIUM AND TOMILD AND STAINLESS STEELS
W. J. LewisP. S. RieppelC. B. Voldricb
Battelle Memorial Institute
Materials LaboratoryContract No. AF 33(038)-23338
RDO No. 615-20
Wright Air Development CenterAir Research and Development Command
United States Air ForceWright-Patterson Air Force Base, Ohio
McGregor & Werner, Inc. Dayton, 0.250 March, 1953
This report was pre'ared by the BattelleMemorial Institute on Contract No. AF 33(039)-23339. The contract was initiated underResearch and Develornent Order No. 615-20,"Welding, Brazing and Soldering of Metals",and was administered under the direction ofthe Materials Laboratory, Directorate of Re-search, Wright Air Development Center, withMajor R. E. Bovnan and Dr. H. K. Adenstedtacting as project engineers. This report coversthe resenrch accomplished during the year end-ing 21 June 1952. Another report will be pre-pared for the year ending 21 June 1953.
WADC TR 52-313 Pt 1
Procedures and alloys suitable for brazing titanium wereinvestigated. Commercial brazing alloys were evaluated by makingbrazed joints of titanium in a furnace containing an atmosphere ofhigh purity argon. The most satisfactory alloys in this type ofbrazing were silver and silver base alloys. Joints with shearstrengths averaging 15,000 psi were obtained by furnace brazingwith the following alloys:
100% silver85% silver, 15% manganese45% silver, 15% copper, 16% zinc, 24% cadmium
Brazed joints ot titanium were also made with the oxy-actylenetorch and a commerical brazing flux. The best alloy found in torchbrazing was a 45% silver, 15% copper, 16% zinc, 24% cadmium alloy,which produced shear strengths averaging 13,000 psi.
The strengths of brazed joints in titanium were somewhat lowerthan that of similar brazed joints of the same alloys in carbon steels.The lower strengths are believed to be associated with the inter-metallic compounds which formed at the boundaries between the brazingalloy and titanium. Also, broad zones of diffusion were present atsome of the boundaries. Some of the intermetallic compounds appearedto be brittle. Silver and the 85% silver-15% manganese alloy werethe only brazing alloys that produced joints exhibiting some ductility.
In order to reduce compound formation and diffusion, a few pre-liminary tests were made using shorter brazing cycles. This wasaccomplished with induction, resistance, and shielded carbon-arcbrazing methods. These tests indicated that the formation of inter-metallic compounds can be reduced by using shorter heating cycles.This phase of the investigation will be covered in more detail in asecond report.
This report has been reviewed and is approved.
FOR TH7 COMMANDING GENTMAL:
/" M. E. SORTE
Colonel, USAFChief, Materials LaboratoryDirectorate of Research
WADC TR 52-313 Pt I iii
TABLE OF CONTENTS
INTRODUCTION ....... . . . . . . . . . . . . 1
SUMMARY . . . . . . . . . . . . . . . .. .. . . . . ..
PREPARATION OF TITANIUM-BASE MATERIAL . . . . . . 3
EVALUATION OF COMMERCIAL BRAZING ALLOYS . . . . 3
Preliminary Evaluation Tests . . . . . . . . . . . 4Tests With Selected Alloys . . . . . . . . .. . .. 16
Furnace-Brazing Tests . . . . . . . . .. 16
Procedure . . . . . * . * * * . . . . 18
Results .................... o . . . . . 18Torch-Brazing Tests . . . .. . ... .. . 24
Procedure ................ . . . .* . . 24Results ......... ............ . . . .. 24
Exploration of Other Brazing Methods. . . . . . . 27
Resistance Brazing ............ . . 27
Induction Brazing . . . . . . . . . . . . 27
Shielded Carbon-Arc Brazing . . . . . . . . 27
EXPERIMENTS WITH BRAZING FLUXES .... ............ o 27
DEVELOPMENT OF EXPERIMENTAL ALLOYS . . . . . . . 28
Titanium-Base Alloys . . # . . ........ . . 29Results ............ .................... ..... 30
Modified Commercial Alloys . . . . . . . o . . o 31
Results .... ............... . .. .. . 31
GENERAL DISCUSSION . . . . . . . . . ....... . . 32
FUTURE WORK .................. .. . . . 34
WADeC T 52-313 Ft 1 iv
Brazing Tit anium to Titaniumand to
Mild a n d Stainless SteelsThTMMfUCTION
Titanium and its alloys are assuming an important place in aircraftstructures. In using these materials, it is anticipated that brazed jointswill often be needed. Recognizing this situation, the Wright Air DevelopmentCenter authorized this investigation of the brazing of titanium.
The broad objective of the investigation was to evaluate commerciallyavailable alloys and to develop new alloys for use in joining titanium totitanium, to mild steel, and to stainless steel. The investigation was con-ducted through the period from June 21, 1951, to June 21, 1952.
Titanium was successfully brazed with several alloys in a controlled-atmosphere furnace in high-purity argon. It was also brazed with anoxyacetylene torch using a commercial brazing flux. Other brazingmethods investigated were resistance, induction, and inert-gas -shieldedcarbon arc. Good results were obtained on a limited number of prelimi-nary tests with these three methods.
A series of experimental titanium-base alloys and modified com-mercial alloys was prepared and tested. The melting points of thetitanium-base alloys were all above Z000 F, which is too high for good re-sults with slow-brazing cycles of furnace and torch brazing.
During the next contract period, attempts will be made to improvebrazing methods and techniques, to improve the quality of brazed joints.Emphasis will be placed on shortening the brazing cycle to a minimum toreduce the formation of intermetallic compounds in the brazed joints.Induction and resistance brazing will be explored. Design of brazed jointswill be studied to improve strength.
This report describes the evaluation of various commercial brazingalloys, the brazing equipment and procedures used, metallographic studiesof brazed Joints, and results obtained in brazing tests. Studies of experi-mental alloys and fluxes are also discussed.
The commercially pure Process A titanium used in the brazingstudies was melted, forged, rolled, annealed, and pickled at Battelle.This material was used to make single-lap brazed joints of titanium to
WADC TR 52-313 Pt 1 1
titanium, titanium to stainless steel, and titanium to mild steel, usingalloys selected from a survey of commercial brazing alloys. This brazingwas done in argon in a controlled-atmosphere retort. Some tests werealso made by torch brazing using a commercial flux. Double-lap-jointspecimens were furnace brazed in an inert atmosphere and torch brazedusing five selected alloys which had produced the strongest joints in thispreliminary study.
Each alloy selected from the preliminary study was used to brazefive specimens of each combination of titanium to titanium, titanium tomild steel, and titanium to stainless steel. These specimens were testedin a tension machine to determine whether their strengths were consistentthroughout each series of five tests. In general, furnace-brazed speci-mens had higher strengths and showed greater consistency than specimenstorch brazed with the same alloys. The tests show that pure silver, an85 per cent silver - 15 per cent manganese alloy, and a 45 per cent silver -15 per cent copper - 16 per cent zinc - 24 per cent cadmium alloy producedshear strengths averaging 15, 000 psi in furnace brazing titanium. Thebest alloy found in torch brazing was a 45 per cent silver - 15 per centcopper - 16 per cent zinc - 24 per cent cadmium alloy, which producedshear strengths averaging 13, 000 psi. The only joints that exhibited duc-tility were those made in the furnace using pure silver and an alloy of85 per cent silver and 15 per cent manganese.
A few preliminary tests were made using induction, resistance, andshielded carbon-arc brazing methods. Joints made with these differentmethods show that greater strengths can be obtained because of the shorterbrazing cycles. The shorter brazing cycle prevents dilution of the brazingalloy and formation of intermetallic compounds.