EP0915180A1 - Process for enhancing the bond strength of resistance welded joints between titanium alloy articles - Google Patents

Process for enhancing the bond strength of resistance welded joints between titanium alloy articles Download PDF

Info

Publication number
EP0915180A1
EP0915180A1 EP97117489A EP97117489A EP0915180A1 EP 0915180 A1 EP0915180 A1 EP 0915180A1 EP 97117489 A EP97117489 A EP 97117489A EP 97117489 A EP97117489 A EP 97117489A EP 0915180 A1 EP0915180 A1 EP 0915180A1
Authority
EP
European Patent Office
Prior art keywords
titanium alloy
articles
hours
heat treating
resistance welding
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP97117489A
Other languages
German (de)
French (fr)
Other versions
EP0915180B1 (en
Inventor
Sami M. El-Soudani
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Boeing Co
Original Assignee
Boeing North American Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Boeing North American Inc filed Critical Boeing North American Inc
Priority to ES97117489T priority Critical patent/ES2188844T3/en
Priority to DE1997618648 priority patent/DE69718648T2/en
Priority to EP19970117489 priority patent/EP0915180B1/en
Publication of EP0915180A1 publication Critical patent/EP0915180A1/en
Application granted granted Critical
Publication of EP0915180B1 publication Critical patent/EP0915180B1/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
    • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
    • C22F1/16—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of other metals or alloys based thereon
    • C22F1/18—High-melting or refractory metals or alloys based thereon
    • C22F1/183—High-melting or refractory metals or alloys based thereon of titanium or alloys based thereon

Definitions

  • the present invention relates to methods for processing titanium alloys and, more particularly, to a process for enhancing the bond strength of a metallurgical joint between two titanium alloy articles.
  • HSCT high speed civil transport
  • HSCT emphasis is on the use of titanium alloys because, under Mach 2.4 conditions, they exhibit damage tolerance and durability, as well as thermal stability, required for the expected 72,000 hours at supersonic cruise temperatures of about 350°F throughout one airplane lifetime. At such temperatures, virtually all heat treatable aluminum alloys experience aging degradation of critical properties, such as fracture toughness, with prolonged duration of service exposure. The outcome of recent investigations suggests that the maximum use temperature for the most advanced aluminum-lithium alloys is about 225°F. This conclusion inevitably minimizes the use of aluminum alloys as outer skins and associated structures. If a similar conclusion is drawn for non-metallic composites, then only titanium alloys would remain as the sole viable candidate material system for such high temperature, long life applications.
  • Enhancement of titanium alloy properties has been achieved in the process disclosed and claimed in U. S. Patent Serial No. 08/339,856, entitled "A Method for Processing-Microstructure-Property Optimization of Alpha-Beta Titanium Alloys to Obtain Simultaneous Improvements in Mechanical Properties and Fracture Resistance", assigned to Rockwell International Corporation.
  • Resistance welded honeycomb titanium alloy structures are known in the field. However, they tend to exhibit lower flatwise tension strength in comparison with other joining methods, e.g. aluminum brazed honeycomb or transient liquid phase bonding. Post-weld thermal processing is important. As will be disclosed below, the present patent application describes an improved processing sequence in this field.
  • Another object of the present invention is to provide an efficient joining of face sheets to a honeycomb core element with improved balance of strength properties of the face sheets and the core element.
  • the present invention provides the above-mentioned improved thermal processing parameters for joint enhancement in titanium alloys after resistance welding.
  • the present Applicant has found that, in the specified temperature range and period of time, the inter-diffusion of joint materials takes place at such higher rates as to provide enhanced homogeneous bend interface microstructures, which, in turn, provide for higher interface bond strength. Surprisingly, such high temperatures are required to eliminate interfacial oxide layers and other defective microstructures.
  • Figure 1 shows two titanium alloy face sheets 10, 12, which are to be joined to a titanium alloy honeycomb core element 14.
  • the face sheets 10, 12 may be formed of, for example, alpha-beta titanium alloys.
  • the titanium alloy articles may be near alpha or beta alloys.
  • the principles of the present invention, as will be disclosed below, are particularly advantageous with the use of a honeycomb core element 14.
  • Honeycomb core elements are particularly advantageous because they provide the capability of greater weight reductions for the same structural stiffness. Such honeycomb core structures and other stiffened structures are commonly used in the construction of aircraft.
  • FIG. 1 a block schematic diagram of the fabrication processing sequence for joint enhancement, while transforming titanium alloy article microstructures from ⁇ + ⁇ to ⁇ + ⁇ 2 + ⁇ is illustrated, designated generally as 16.
  • Two titanium alloy articles having ⁇ + ⁇ microstructures 18 are resistance welded.
  • the resistance welding technique is well know in this field. In the resistance welding technique two materials are brought together under pressure and large electrical currents are applied through the contact interface between the two articles. As a result of electrical resistance heating at the contact interface, a small weld nugget of molten metal is formed, thus achieving the bond upon its solidification.
  • This step of resistance welding may be applied in different configurations by spot welds or continuous seem welds.
  • the ⁇ + ⁇ microstructrue is maintained, even after resistance welding, as shown by block 20.
  • the bonded materials are brought together in contact, which extends over areas outside the molten weld nuggets.
  • the articles are then heat treated at temperatures in a range of 1675°F to 1825°F for a period of 15 minutes to 4 hours to further bond additional contact areas brought together by the shrinkage stresses exerted by the resistance weld.
  • This heat treatment step also converts the ⁇ + ⁇ microstructure to an ⁇ + ⁇ 2 + ⁇ microstructure as shown by block 22.
  • a broad range of temperatures and a broad heat treatment period was discussed above, it is preferred that the heat treatment be in a range of between about 1700°F and 1800°F fora period of 1-3 hours.
  • the heat treatment step discussed herein is provided in a vacuum or inert environment, preferably a vacuum environment. (If an inert environment is used, it should be pure argon or helium.)
  • FIG. 3 the processing techniques of the present invention are illustrated, as applied to titanium alloy articles having ⁇ + ⁇ 2 + ⁇ microstructures initially, as designated generally by 24.
  • the ⁇ + ⁇ 2 + ⁇ titanium alloy articles 26 are resistance welded as discussed above in the previous embodiment.
  • the ⁇ + ⁇ , + ⁇ microstructure is preserved, as shown by numeral designation 28.
  • the joined articles are then heat treated. It is understood that the ⁇ + ⁇ 2 + ⁇ microstructure is retained in the bonded articles with the exception of the weld nugget, which may be ⁇ + ⁇ .
  • the heat treatment temperature ranges and time periods are as discussed above with respect to the Figure 2 embodiment.
  • the ⁇ + ⁇ 2 + ⁇ microstructure is preserved/regenerated after heat treatment, as shown by block 30.
  • FIG 4 a micrograph of a typical resistance spot welded metallurgical bond joint is illustrated, in accordance with the principles of the first step of the present process.
  • This bond joint designated generally as 32.
  • the materials joined in Figure 4 are a Ti 6242S face sheet 34 and a honeycomb core of Beta 21S alloy, designated by numeral designation 36.
  • the micrograph shows a weld nugget of molten metal 38 adjacent to a contact surface 40.
  • Figure 5 shows a cross section of the contact surface following post-weld thermal processing at an undesirably low subsequent heat treatment processing temperature of 1625°F, for two hours.
  • the interface morphology is substantially the same as the interface 40 of the solely resistance spot welded sample of Figure 4.
  • Figure 6 illustrates the advantages of the higher temperature heat treatment of the present invention.
  • the articles were heated to 1800°F for two hours.
  • the interface morphology comprises a very broad domain of diffusion with mutually attractive phases. This substantially increases the bond strength of the joint.
  • Figure 7 illustrates the results of mechanical tests comprised of flatwise tension testing of small honeycomb elements excised from honeycomb elements processed in accordance with methods discussed above with respect to Figures 5 and 6.
  • reference to "Conventional Processing” means processing described above with respect to Figure 5, that is at 1625°F heat treatments.
  • Reference to "Present Invention Improved Processing” means heat treatments in accordance with the discussion of Figure 6 of the present invention (1800°F heat treatment for two hours).
  • the flatwise tension test is a well known method in evaluating the strength of honeycomb sandwiches. It consists of bonding pull bar elements to the faces of a honeycomb segment measuring about 2 x 2 inches. In this test, the tensile forces are thus directed to separate the face sheets from the core element in a direction normal to the face sheet.
  • the process of the present invention provides a substantial increase in the strength of the face sheet to core bond joint strength. This is due to the improved interface diffusion illustrated in Figure 6 as compared to the prior art Figure 5.
  • the left side of the graph presents the average values of the measured flatwise tension strength test results shown in Figure 7.
  • the right side of Figure 8 shows a comparison of the associated core node bond strength.
  • the nodes were prepared by resistance spot welding similar to that illustrated in Figure 4.
  • the strength enhancement of the core node bond is due to the same effects, which improved the face sheet to core bond joint.
  • the present invention preferably includes a step of cooling the titanium alloy articles after the step of heat treating discussed above, and then aging the articles at a temperature in a range of about 850°F to 1150°F for a period of about 8 hours to 24 hours to prevent silicide precipitation.
  • the step of aging preferably comprises aging the articles at a temperature of about 1100°F. It is understood that the step of cooling comprises cooling in a protective environment. This step of cooling is preferably conducted at a cooling rate in a range of 5°F per minute to 500°F per minute.
  • the process of the present invention does not require such a complicating process application.
  • the bonded surfaces outside the weld zone are brought together in solid contact by the shrinkage stresses of the resistance welds in the absence of the external mechanical forces acting on the titanium alloy articles.
  • the invention relates to a process for enhancing the bond strength of a metallurgical joint between two titanium alloy articles, comprising the step of:

Landscapes

  • Chemical & Material Sciences (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Pressure Welding/Diffusion-Bonding (AREA)
  • Arc Welding In General (AREA)
  • Professional, Industrial, Or Sporting Protective Garments (AREA)

Abstract

A process for enhancing the bond strength of resistance welded joints between titanium alloy articles includes a first step of resistance welding two titanium alloy articles and a second step of heat treating the resistance welded titanium alloy articles in a vacuum or inert environment at temperatures in a range of 1675°F to 1825°F for a period of 15 minutes to 4 hours. The process of the present invention is particularly useful in providing efficient joining of face sheets to a honeycomb core element.

Description

    BACKGROUND OF THE INVENTION 1. Field of the Invention
  • The present invention relates to methods for processing titanium alloys and, more particularly, to a process for enhancing the bond strength of a metallurgical joint between two titanium alloy articles.
    • 2. Description of the Related Art
  • The high performance technologies of the future will impose increasing demands on new improved lightweight, high strength materials, such as titanium alloys.
  • One area of interest is the high speed civil transport (HSCT) aircraft. The main focus of the HSCT is to upgrade proposed aircraft structures to be compatible with Mach 2.4 vehicle requirements for the purpose of replacing or upgrading the existing Concorde Mach 2.0 technology.
  • Currently, HSCT emphasis is on the use of titanium alloys because, under Mach 2.4 conditions, they exhibit damage tolerance and durability, as well as thermal stability, required for the expected 72,000 hours at supersonic cruise temperatures of about 350°F throughout one airplane lifetime. At such temperatures, virtually all heat treatable aluminum alloys experience aging degradation of critical properties, such as fracture toughness, with prolonged duration of service exposure. The outcome of recent investigations suggests that the maximum use temperature for the most advanced aluminum-lithium alloys is about 225°F. This conclusion inevitably minimizes the use of aluminum alloys as outer skins and associated structures. If a similar conclusion is drawn for non-metallic composites, then only titanium alloys would remain as the sole viable candidate material system for such high temperature, long life applications.
  • On the other hand, severe goal property requirements have been imposed on titanium alloys by major aircraft vehicle contractors. As yet, these requirements remain beyond reach by all of the current state-of-the-art titanium alloys.
  • Substantial weight reductions and more efficient system performances have been achieved through replacements of the heavier superalloys and/or steels with titanium, which, in turn, may have to be fabricated in the form of lightweight structural components such as efficient honeycomb sandwiches, in view of the severe demands of ultra light weight HSCT and/or other aerospace structural applications.
  • Enhancement of titanium alloy properties has been achieved in the process disclosed and claimed in U. S. Patent Serial No. 08/339,856, entitled "A Method for Processing-Microstructure-Property Optimization of Alpha-Beta Titanium Alloys to Obtain Simultaneous Improvements in Mechanical Properties and Fracture Resistance", assigned to Rockwell International Corporation.
  • Resistance welded honeycomb titanium alloy structures are known in the field. However, they tend to exhibit lower flatwise tension strength in comparison with other joining methods, e.g. aluminum brazed honeycomb or transient liquid phase bonding. Post-weld thermal processing is important. As will be disclosed below, the present patent application describes an improved processing sequence in this field.
    • OBJECTS AND SUMMARY OF THE INVENTION
  • It is, therefore, a principal object of the present invention to enhance the bond strengths of metallurgical joints between titanium alloy articles.
  • Another object of the present invention is to provide an efficient joining of face sheets to a honeycomb core element with improved balance of strength properties of the face sheets and the core element.
  • These and other objects are achieved by the present process, which includes, in its broadest aspects, the steps of:
  • a) resistance welding two titanium alloy articles; and
  • b) heat treating the resistance welded titanium alloy articles in a vacuum or inert environment at temperatures in a range of 1675°F to 1825°F for a period of 15 minutes to 4 hours.
  • Although, in the past, titanium alloy articles have been resistance welded and post-weld thermally processed for joint enhancement, such post-weld treatments have not been entirely successful due to deficient processing parameters for the given material. The present invention provides the above-mentioned improved thermal processing parameters for joint enhancement in titanium alloys after resistance welding. The present Applicant has found that, in the specified temperature range and period of time, the inter-diffusion of joint materials takes place at such higher rates as to provide enhanced homogeneous bend interface microstructures, which, in turn, provide for higher interface bond strength. Surprisingly, such high temperatures are required to eliminate interfacial oxide layers and other defective microstructures.
  • Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.
    • BRIEF DESCRIPTION OF THE DRAWINGS
  • Figure 1 is an exploded perspective view of portions of typical articles being metallurgically joined by the process of the present invention.
  • Figure 2 is a block schematic diagram of the fabrication processing sequence for joint enhancement while transforming titanium alloy article microstructures from α + β to α + α2 + β.
  • Figure 3 is a block diagram of the fabrication processing sequence for joint enhancement while retaining/regenerating the α + α2 + β microstructure.
  • Figure 4 is a micrograph of a typical metallurgical bond joint (resistance spot weld) in accordance with the principles of the first step of the present invention.
  • Figure 5 is a micrograph showing a deficient bond interface between a Ti 6242S face sheet and Beta 21S honeycomb core resulting from a conventional relatively low temperature heat treatment (1625°F heat treatment for 2 hours).
  • Figure 6 is a micrograph showing a bend interface between a Ti 6242S face sheet and a Beta 21S honeycomb core resulting from processing in accordance with the principles of the present invention (18000F heat treatment for 2 hours).
  • Figure 7 is a graph of flatwise tension strength as a function of post-weld processing temperatures and hold times for various test specimens illustrating the respective strength property scatter bands of bond joints.
  • Figure 8 is a graph of flatwise tension strength as a function of post weld processing methods, showing the superior bond enhancement of the present invention both at face-sheet-to-core joint and core-to-core joint.
  • Figures 9a-d are block diagrams illustrating the fabrication processing sequence of the present invention, as applied to various alpha/beta titanium alloy systems.
  • The same elements or parts throughout the figures are designated by the same reference characters.
    • DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
  • Referring now to the drawings and the characters of reference marked thereon, Figure 1 shows two titanium alloy face sheets 10, 12, which are to be joined to a titanium alloy honeycomb core element 14. The face sheets 10, 12 may be formed of, for example, alpha-beta titanium alloys. Alternatively, the titanium alloy articles may be near alpha or beta alloys. The principles of the present invention, as will be disclosed below, are particularly advantageous with the use of a honeycomb core element 14. However, it is understood that other types of core element configurations are within the purview of this invention. Honeycomb core elements are particularly advantageous because they provide the capability of greater weight reductions for the same structural stiffness. Such honeycomb core structures and other stiffened structures are commonly used in the construction of aircraft.
  • Referring now to Figure 2, a block schematic diagram of the fabrication processing sequence for joint enhancement, while transforming titanium alloy article microstructures from α + β to α + α2 + β is illustrated, designated generally as 16. Two titanium alloy articles having α + β microstructures 18 are resistance welded. The resistance welding technique is well know in this field. In the resistance welding technique two materials are brought together under pressure and large electrical currents are applied through the contact interface between the two articles. As a result of electrical resistance heating at the contact interface, a small weld nugget of molten metal is formed, thus achieving the bond upon its solidification. This step of resistance welding may be applied in different configurations by spot welds or continuous seem welds. The α + β microstructrue is maintained, even after resistance welding, as shown by block 20.
  • Upon weld metal shrinkage, the bonded materials are brought together in contact, which extends over areas outside the molten weld nuggets. In accordance with the process of the present invention, the articles are then heat treated at temperatures in a range of 1675°F to 1825°F for a period of 15 minutes to 4 hours to further bond additional contact areas brought together by the shrinkage stresses exerted by the resistance weld. This heat treatment step also converts the α + β microstructure to an α + α2 + β microstructure as shown by block 22. Although a broad range of temperatures and a broad heat treatment period was discussed above, it is preferred that the heat treatment be in a range of between about 1700°F and 1800°F fora period of 1-3 hours. The heat treatment step discussed herein is provided in a vacuum or inert environment, preferably a vacuum environment. (If an inert environment is used, it should be pure argon or helium.)
  • Referring now to Figure 3, the processing techniques of the present invention are illustrated, as applied to titanium alloy articles having α + α2 + β microstructures initially, as designated generally by 24. The α + α2 + β titanium alloy articles 26 are resistance welded as discussed above in the previous embodiment. The α + α, + β microstructure is preserved, as shown by numeral designation 28. The joined articles are then heat treated. It is understood that the α + α2 + β microstructure is retained in the bonded articles with the exception of the weld nugget, which may be α + β. The heat treatment temperature ranges and time periods are as discussed above with respect to the Figure 2 embodiment. The α + α2 + β microstructure is preserved/regenerated after heat treatment, as shown by block 30.
  • Referring now to Figure 4, a micrograph of a typical resistance spot welded metallurgical bond joint is illustrated, in accordance with the principles of the first step of the present process. This bond joint designated generally as 32. The materials joined in Figure 4 are a Ti 6242S face sheet 34 and a honeycomb core of Beta 21S alloy, designated by numeral designation 36. The micrograph shows a weld nugget of molten metal 38 adjacent to a contact surface 40.
  • Figure 5 (Prior Art) shows a cross section of the contact surface following post-weld thermal processing at an undesirably low subsequent heat treatment processing temperature of 1625°F, for two hours. The interface morphology is substantially the same as the interface 40 of the solely resistance spot welded sample of Figure 4.
  • Figure 6 illustrates the advantages of the higher temperature heat treatment of the present invention. In this sample, the articles were heated to 1800°F for two hours. The interface morphology comprises a very broad domain of diffusion with mutually attractive phases. This substantially increases the bond strength of the joint.
  • Figure 7 illustrates the results of mechanical tests comprised of flatwise tension testing of small honeycomb elements excised from honeycomb elements processed in accordance with methods discussed above with respect to Figures 5 and 6. In Figure 7, reference to "Conventional Processing" means processing described above with respect to Figure 5, that is at 1625°F heat treatments. Reference to "Present Invention Improved Processing" means heat treatments in accordance with the discussion of Figure 6 of the present invention (1800°F heat treatment for two hours). The flatwise tension test is a well known method in evaluating the strength of honeycomb sandwiches. It consists of bonding pull bar elements to the faces of a honeycomb segment measuring about 2 x 2 inches. In this test, the tensile forces are thus directed to separate the face sheets from the core element in a direction normal to the face sheet. As can be seen by Figure 7, the process of the present invention provides a substantial increase in the strength of the face sheet to core bond joint strength. This is due to the improved interface diffusion illustrated in Figure 6 as compared to the prior art Figure 5.
  • Referring now to Figure 8, the left side of the graph presents the average values of the measured flatwise tension strength test results shown in Figure 7. The right side of Figure 8 shows a comparison of the associated core node bond strength. The nodes were prepared by resistance spot welding similar to that illustrated in Figure 4. The strength enhancement of the core node bond is due to the same effects, which improved the face sheet to core bond joint.
  • The present invention preferably includes a step of cooling the titanium alloy articles after the step of heat treating discussed above, and then aging the articles at a temperature in a range of about 850°F to 1150°F for a period of about 8 hours to 24 hours to prevent silicide precipitation. The step of aging preferably comprises aging the articles at a temperature of about 1100°F. It is understood that the step of cooling comprises cooling in a protective environment. This step of cooling is preferably conducted at a cooling rate in a range of 5°F per minute to 500°F per minute.
  • Unlike diffusion bond applications of the prior art, which generally involve the application of high pressures, the process of the present invention does not require such a complicating process application. The bonded surfaces outside the weld zone are brought together in solid contact by the shrinkage stresses of the resistance welds in the absence of the external mechanical forces acting on the titanium alloy articles.
  • Obviously, many modifications and variations of the present invention are possible in light of the above teachings. For example, Figures 9a-d illustrates various other alpha/beta titanium alloy systems which may utilize the principles of the present invention. It is, therefore, to be understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically described. What is claimed and desired to be secured by Letters Patent of the United States is:
  • According to its broadest aspect the invention relates to a process for enhancing the bond strength of a metallurgical joint between two titanium alloy articles, comprising the step of:
  • a) resistance welding two titanium alloy articles; and
  • b) heat treating said resistance welded titanium alloy articles.
  • It should be noted that the objects and advantages of the invention may be attained by means of any compatible combination(s) particularly pointed out in the items of the following summary of the invention and the appended claims.
    • SUMMARY OF THE INVENTION
  • 1. A process for enhancing the bond strength of a metallurgical joint between two titanium alloy articles, comprising the steps of:
  • a) resistance welding two titanium alloy articles; and
  • b) heat treating said resistance welded titanium alloy articles in a vacuum or inert environment at temperatures in a range of 1675°F to 1825°F for a period of 15 minutes to 4 hours, wherein said process is performed in the absence of any substantial external mechanical forces intended for enhancing the metallurgical joint between said titanium alloy articles.
  • 2. The process wherein said step of resistance welding comprises resistance welding a honeycomb core structure with a face sheet.
  • 3. The process wherein said step of resistance welding comprises resistance welding α + β titanium alloy articles; and wherein said step of heat treating comprises heat treating in a range of 1700°F to 1800°F for a period of 1-3 hours.
  • 4. The process , wherein said step of resistance welding comprises:
  • resistance welding at least one α + β titanium alloy article to a second titanium alloy article; and
    wherein said step of heat treating comprises heat treating in a range of between 1700°F - 1800°F for a period of 1-3 hours to transform said at least one α + β titanium alloy article into an α + α2 + β titanium alloy article.
  • 5. The process wherein said second titanium alloy article also has an α + β microstructure.
  • 6. The process wherein said step of resistance welding comprises:
  • resistance welding at least one α + α2 + β titanium alloy article to a titanium alloy article; and
    wherein said step of heat treating comprises heat treating in a range of between 1700°F - 1800°F for a period of 1-3 hours.
  • 7. The process wherein said second titanium alloy article also has an α + α2 + β microstructure.
  • 8. The process wherein said step of heat treating is conducted in a vacuum environment.
  • 9. The process further including a step of cooling said titanium alloy articles after said step of heat treating and then aging said articles at a temperature in a range of about 850°F to 1150°F for a period of about 8 hours to 24 hours to prevent silicide precipitation.
  • 10. The process wherein said step of aging comprises aging said articles at a temperature of about 1100°F.
  • 11. A process for enhancing the bond strength of a metallurgical joint between two titanium alloy articles, comprising the steps of:
  • a) resistance welding two titanium alloy articles;
  • b) heat treating said resistance welded titanium alloy articles in a vacuum or inert environment at temperatures in a range of 1675°F to 1825°F for a period of 15 minutes to 4 hours, wherein said process is performed in the absence of any substantial external mechanical forces intended for enhancing the metallurgical joint between said titanium alloy articles;
  • c) cooling said titanium alloy articles; and
  • d) aging said articles at a temperature in a range of 850°F to 1150°F for a period of 8 hours to 24 hours.

Claims (10)

  1. A process for enhancing the bond strength of a metallurgical joint between two titanium alloy articles, comprising the steps of:
    a) resistance welding two titanium alloy articles; and
    b) heat treating said resistance welded titanium alloy articles in a vacuum or inert environment at temperatures in a range of 1675°F to 1825°F for a period of 15 minutes to 4 hours, wherein said process is performed in the absence of any substantial external mechanical forces intended for enhancing the metallurgical joint between said titanium alloy articles.
  2. The process of Claim 1, wherein said step of resistance welding comprises resistance welding a honeycomb core structure with a face sheet.
  3. The process of Claim 1, wherein said step of resistance welding comprises resistance welding α + β titanium alloy articles; and wherein said step of heat treating comprises heat treating in a range of 1700°F to 1800°F for a period of 1-3 hours.
  4. The process of Claim 1, wherein said step of resistance welding comprises:
    resistance welding at least one α + β titanium alloy article to a second titanium alloy article; and
    wherein said step of heat treating comprises heat treating in a range of between 1700°F - 1800°F for a period of 1-3 hours to transform said at least one α + β titanium alloy article into an α + α2 + β titanium alloy article.
  5. The process of Claim 4, wherein said second titanium alloy article also has an α + β microstructure.
  6. The process of Claim 1, wherein said step of resistance welding comprises:
    resistance welding at least one α + α2 + β titanium alloy article to a titanium alloy article; and
    wherein said step of heat treating comprises heat treating in a range of between 1700°F 1800°F for a period of 1-3 hours.
  7. The process of Claim 1, wherein said second titanium alloy article also has an α + α2 + β microstructure.
  8. The process of Claim 1, wherein said step of heat treating is conducted in a vacuum environment, and/or wherein said process of claim 1
    further including a step of cooling said titanium alloy articles after said step of heat treating and then aging said articles at a temperature in a range of about 850°F to 1150°F for a period of about 8 hours to 24 hours to prevent silicide precipitation,
    and/or wherein preferably said step of aging comprises aging said articles at a temperature of about 1100°F.
  9. A process for enhancing the bond strength of a metallurgical joint between two titanium alloy articles, comprising the steps of:
    a) resistance welding two titanium alloy articles;
    b) heat treating said resistance welded titanium alloy articles in a vacuum or inert environment at temperatures in a range of 1675°F to 1825°F for a period of 15 minutes to 4 hours, wherein said process is performed in the absence of any substantial external mechanical forces intended for enhancing the metallurgical joint between said titanium alloy articles;
    c) cooling said titanium alloy articles; and
    d) aging said articles at a temperature in a range of 850°F to 1150°F for a period of 8 hours to 24 hours.
  10. A process for enhancing the bond strength of a metallurgical joint between two titanium alloy articles, comprising the step of:
    a) resistance welding two titanium alloy articles; and
    b) heat treating said resistance welded titanium alloy articles.
EP19970117489 1997-10-09 1997-10-09 Process for enhancing the bond strength of resistance welded joints between titanium alloy articles Expired - Lifetime EP0915180B1 (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
ES97117489T ES2188844T3 (en) 1997-10-09 1997-10-09 PROCEDURE TO INCREASE THE UNION RESISTANCE OF WELDED JOINTS BETWEEN TITANIUM ALLOY ARTICLES.
DE1997618648 DE69718648T2 (en) 1997-10-09 1997-10-09 Process for improving the adhesive strength between welded titanium alloy objects
EP19970117489 EP0915180B1 (en) 1997-10-09 1997-10-09 Process for enhancing the bond strength of resistance welded joints between titanium alloy articles

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP19970117489 EP0915180B1 (en) 1997-10-09 1997-10-09 Process for enhancing the bond strength of resistance welded joints between titanium alloy articles

Publications (2)

Publication Number Publication Date
EP0915180A1 true EP0915180A1 (en) 1999-05-12
EP0915180B1 EP0915180B1 (en) 2003-01-22

Family

ID=8227460

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19970117489 Expired - Lifetime EP0915180B1 (en) 1997-10-09 1997-10-09 Process for enhancing the bond strength of resistance welded joints between titanium alloy articles

Country Status (3)

Country Link
EP (1) EP0915180B1 (en)
DE (1) DE69718648T2 (en)
ES (1) ES2188844T3 (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104400202A (en) * 2014-10-27 2015-03-11 四川成发航空科技股份有限公司 Resistance positioned welding limiting tool suitable for sealed assembling of small-diameter honeycomb
FR3100466A1 (en) * 2019-09-09 2021-03-12 Safran Nacelles Method of brazing a powertrain panel using different input alloys
FR3106290A1 (en) * 2019-09-09 2021-07-23 Safran Nacelles Structural and / or acoustic panel for an aircraft propulsion system

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0466606A1 (en) * 1990-07-13 1992-01-15 Sumitomo Metal Industries, Ltd. Process for manufacturing corrosion-resistant welded titanium alloy tubes and pipes

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0466606A1 (en) * 1990-07-13 1992-01-15 Sumitomo Metal Industries, Ltd. Process for manufacturing corrosion-resistant welded titanium alloy tubes and pipes

Non-Patent Citations (4)

* Cited by examiner, † Cited by third party
Title
K.C.WU ET AL: "CORRELATION OF PROPERTIES AND MICROSTRUCTURE IN WELDED TI-6AL-4V-2SN", WELDING JOURNAL. INCLUDING: WELDING RESEARCH, vol. 60, no. 11, November 1981 (1981-11-01), MIAMI US, pages 219S - 226S, XP002057699 *
KOLOMENSKII A B ET AL: "EFFECT OF ANNEALING IN VARIOUS MEDIA AND OF PURIFYING PICKLING ON THE ENDURANCE OF WELDED JOINTS IN SHEETS OF VT6CH (TITANIUM) ALLOY", WELDING INTERNATIONAL, vol. 3, no. 1, 1989, pages 42 - 44, XP000027087 *
LYASOTSKAYA V S ET AL: "THERMOCYCLIC HIGH FREQUENCY TREATMENT OF WELDED JOINTS IN VT22 TITANIUM ALLOY", WELDING INTERNATIONAL, vol. 5, no. 5, 1 January 1991 (1991-01-01), pages 389 - 391, XP000226477 *
M.D.DONACHIE JNR: "TITANIUM - A TECHNICAL GUIDE", 1988, ASTM, OHIO, US, XP002057700 *

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104400202A (en) * 2014-10-27 2015-03-11 四川成发航空科技股份有限公司 Resistance positioned welding limiting tool suitable for sealed assembling of small-diameter honeycomb
CN104400202B (en) * 2014-10-27 2016-10-05 四川成发航空科技股份有限公司 It is applicable to minor diameter honeycomb seal assembling resistance tack welding limiting tool
FR3100466A1 (en) * 2019-09-09 2021-03-12 Safran Nacelles Method of brazing a powertrain panel using different input alloys
FR3106290A1 (en) * 2019-09-09 2021-07-23 Safran Nacelles Structural and / or acoustic panel for an aircraft propulsion system

Also Published As

Publication number Publication date
EP0915180B1 (en) 2003-01-22
DE69718648T2 (en) 2003-10-30
DE69718648D1 (en) 2003-02-27
ES2188844T3 (en) 2003-07-01

Similar Documents

Publication Publication Date Title
Ellis Joining of aluminium based metal matrix composites
İpekoğlu et al. Effects of initial temper condition and postweld heat treatment on the properties of dissimilar friction-stir-welded joints between AA7075 and AA6061 aluminum alloys
Charit et al. Multi-sheet structures in 7475 aluminum by friction stir welding in concert with post-weld superplastic forming
US5830289A (en) Process for enhancing the bond strength of resistance welded joints between titanium alloy articles
US6543670B2 (en) Interface preparation for weld joints
EP3013514B1 (en) Improved structural elements obtained by linear friction welding
US4691856A (en) Diffusion bonding method using a high energy beam
CA1071037A (en) High temperature titanium braze foil
Kumar et al. Effect of SiC/Si3N4 micro-reinforcement on mechanical and wear properties of friction stir welded AA6061-T6 aluminum alloy
El-Shennawy et al. Metallurgical and mechanical properties of heat treatable aluminum alloy AA6082 welds
Chen et al. Dual-beam laser welding of ultra-thin AA 5052-H19 aluminum
EP0915180B1 (en) Process for enhancing the bond strength of resistance welded joints between titanium alloy articles
Madhusudhan et al. An experimental study on the effect of weld parameters on mechanical and micro structural properties of dissimilar aluminium alloy FS welds
Shirzadi et al. Joining stainless steel metal foams
Dunford et al. Diffusion bonding of Al–Li alloys
US6758388B1 (en) Titanium aluminide honeycomb panel structures and fabrication method for the same
AU733811B2 (en) Process for enhancing the bond strength of resistance welded joints between titanium alloy articles
EP1238741B1 (en) Fabrication method for Titanium aluminide honeycomb panel structures
JP4101333B2 (en) Process for increasing the joint strength of intermetallic joints between titanium alloy parts
Nayeb-Hashemi et al. The effect of processing variables on the microstructures and properties of aluminum brazed joints
GB2241914A (en) Diffusion bonding of aluminium-lithium alloys
Holko Enhanced Diffusion-welding of TD-NiCr Sheet
EP3366407B1 (en) Structure and method of making same involving welding otherwise non-weldable materials
Goddard et al. Feasibility of brazing and welding aluminum-graphite composites
Ditzel Microstructure/property relationships in aluminum friction stir welds

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): DE ES FR GB

17P Request for examination filed

Effective date: 19991111

AKX Designation fees paid

Free format text: DE ES FR GB

17Q First examination report despatched

Effective date: 20001227

GRAG Despatch of communication of intention to grant

Free format text: ORIGINAL CODE: EPIDOS AGRA

GRAG Despatch of communication of intention to grant

Free format text: ORIGINAL CODE: EPIDOS AGRA

GRAH Despatch of communication of intention to grant a patent

Free format text: ORIGINAL CODE: EPIDOS IGRA

GRAH Despatch of communication of intention to grant a patent

Free format text: ORIGINAL CODE: EPIDOS IGRA

GRAA (expected) grant

Free format text: ORIGINAL CODE: 0009210

AK Designated contracting states

Kind code of ref document: B1

Designated state(s): DE ES FR GB

REG Reference to a national code

Ref country code: GB

Ref legal event code: FG4D

REF Corresponds to:

Ref document number: 69718648

Country of ref document: DE

Date of ref document: 20030227

Kind code of ref document: P

ET Fr: translation filed
RAP2 Party data changed (patent owner data changed or rights of a patent transferred)

Owner name: THE BOEING COMPANY

REG Reference to a national code

Ref country code: ES

Ref legal event code: FG2A

Ref document number: 2188844

Country of ref document: ES

Kind code of ref document: T3

PLBE No opposition filed within time limit

Free format text: ORIGINAL CODE: 0009261

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT

26N No opposition filed

Effective date: 20031023

REG Reference to a national code

Ref country code: FR

Ref legal event code: PLFP

Year of fee payment: 19

REG Reference to a national code

Ref country code: FR

Ref legal event code: PLFP

Year of fee payment: 20

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: GB

Payment date: 20161027

Year of fee payment: 20

Ref country code: DE

Payment date: 20161027

Year of fee payment: 20

Ref country code: FR

Payment date: 20161025

Year of fee payment: 20

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: ES

Payment date: 20161026

Year of fee payment: 20

REG Reference to a national code

Ref country code: DE

Ref legal event code: R071

Ref document number: 69718648

Country of ref document: DE

REG Reference to a national code

Ref country code: GB

Ref legal event code: PE20

Expiry date: 20171008

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: GB

Free format text: LAPSE BECAUSE OF EXPIRATION OF PROTECTION

Effective date: 20171008

REG Reference to a national code

Ref country code: ES

Ref legal event code: FD2A

Effective date: 20180508

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: ES

Free format text: LAPSE BECAUSE OF EXPIRATION OF PROTECTION

Effective date: 20171010