September 13, 2011

Rich TenagliaEngineering Manager, Materials and Ultrasonic ProcessingEmail: rtenaglia@ewi.orgPhone: 614.688.5241Overview of Industry Trends and Needs for Dissimilar Materials Joining

IntroductionPresent an overview of the key drivers for dissimilar materials joining applications in various industries.

Major reasons why dissimilar material joints are needed include:

Lightweight structuresStructures with locally tailored propertiesCorrosion resistanceEconomical use of valuable alloysThermal management and electrical conductivityInnovative product designs and functionalityCost reduction

Why is detailed info about DMJ hard to find?Lots of articles referring to use of dissimilar materials, many about modeling and sanitized research about joint properties and testing.

But case studies and details about specific joining process parameters, part designs, joint geometry, costs, and overall performance benefits are almost always missing. Why??

Why is detailed info about DMJ hard to find?Number of Publications from 1970 to 2008 Related to Different Materials Including DMJ

Materials1970-19801981-19901991-20002001-2008Al/Al alloys1521228222901512Cu/Cu alloys122116101627944Co/Co alloys8816715866Mg/Mg alloys112193268360Ni/Ni alloys72312491302516Steel (CS)/low-alloy steel60213231101558Stainless steel105418801812921Cast iron8718115642Ti/Ti alloys 4247881051565Reactive metals/Zr alloys8522627183Precious metals/Au/Ag/Pt339464586272Refractory metals/refractory alloys6721421174Ceramics28216522088950Polymers/plastics19976411841003Composites2247041173879Dissimilar joining/welding3872633766963804

DMJ Needs by Industry

Why is detailed info about DMJ hard to find?Developing a successful dissimilar materials joint is often crucial to the technical and commercial success of a product and is therefore held as proprietary and often viewed as intellectual know-how.

Achieving a successful dissimilar materials joint often requires a significant amount of development work and testing; few companies wish to share at no cost with their competition.

Why all the interest in DMJ?Materials cost so much these days!!..Cr, Ni, Cu, rare earthsalmost everything!We just have to get our quality up, but our costs down!We need innovative products to keep up with our competition!Weve squeezed about all the cost and performance we can from our existing product.

Aerospace - StructuresOpportunities to use different aluminum alloys/tempers for upper and lower wing skins, stringers, and spars.

Each structural part has different strength, formability, and corrosion-resistance requirements.

Solid-state joining techniques being developed to eliminate costly riveting.

Aerospace Engines/BlisksSource: MTU Aero Engines, GmbHOpportunities to use different alloys for hub (stress rupture) and blades (deformation and creep resistance)

Components with better high temperature properties for increased operating efficiency

Design for repair and blade replacement

AerospaceSource: MTU Aero Engines, GmbHEmerging developments for DMJ inertial friction welding for blisk stages, moving from titanium alloy fan blisks to nickel-based hot stages.

Automotive and TransportationMazda MX-5 aluminum trunk lid and steel bolt retainer joined by friction spot welding2012 Audi A6 featuring aluminum and steel constructionTrends toward dissimilar metal joining driven by weight reduction efforts to drive toward new CAFE standards.

Renewed challenges for prevention of galvanic corrosion.

Batteries Hybrid VehiclesNumerous emerging designs for lithium-ion batteriesDissimilar material joining challenges for electric, hybrid, and plug-in hybrid electric vehicles.

Complex material combinations with special needs including:

High production throughput and process robustness, cost reduction, long-term service durability, consistent performance, and improved NDE methods for quality assurance.

Heavy TransportationFuel-efficient freight transportationAluminum-steel rail freight carsRising costs of fuels driving needs to lightweight construction; aluminum and composite parts joined to steel and stainless structures.Fuel-efficient municipal vehicles

Alternative Energy ProductionSolar: Bonding metallic conductors to silicon and glass (coated and uncoated) panel surfaces, ideal for joining of conductors and dissimilar material heat sinks for thermal management. Images courtesy of S-Bond Technologies Wind: High-power transients present thermal management challenges in electrical conversion equipment; various combinations of metals, ceramics, glass, and composites are used.

Thermal Management: Al-Cu and Al-SiC joints finding extensive application in the bonding of cold plates, vapor chambers, heat sinks, and other thermal management components.Sensors: Sensors and sensor housings often require metal-to-metal and/or metal-to-ceramic bonds that make electrical connections or hermetic seals.DMJ driven by the nature of the system components and functional needs for thermal management and electrical conductivity.

MedicalGrowing trends in endoscopic, less-invasive surgical techniques.

Growing trend in single-use, pre-sterilized surgical tools.

Microjoining of expensive titanium and stainless steel parts that are invasive to less expensive, stronger steels for non-invasive portions of devices.

Electronics and TelecommunicationsThe ever increasing need for bandwidth and speed are driving the use of higher powered electronics in telecommunications in local broadcast vans, cell towers, central servers, and satellites.

High-power electronics often require unique thermal management systems, including: passive heat sinks, finned heat exchangers, and actively cooled cold plates.

A requirement to join Al and Cu parts is common, but emerging applications include joining of graphite, aluminum and silicon carbide (Al:SiC) as weight reduction and increased thermal performance are needed.

Oil and GasNew oil and gas production fields face material challenges for arctic or deep, sour gas (H2S-containing) environments.

Growing need for lower-cost cladding approaches for corrosion resistance and improved joining of bimetallic riser pipe.

Other DMJ needs involve metal-ceramic joining for sensors and housings to guide smart drilling systems and wear seals.X65 Steel pipe with Inconel 625 inner claddingImage courtesy Voest-Alpine

Summary - Takeaways

Joint design and material thicknessesDifferences in melting temperatureThermal expansion-contraction mismatch during joining and in serviceFixturing and constraint effects on joining stressesFormation of brittle intermetallic compounds during joining which may lead to brittle jointsHeating and cooling rate effects on the microstructure of the jointNeeds for pre and post heatingNeeds for composite transition materials or special filler materials during joiningPotential for galvanic corrosion problems in service

DMJ is more involved than just a material combination lots to consider..EWIs experience and knowledge with dissimilar materials joining can help you meet your needs.

Questions?Rich TenagliaEngineering Manager, Materials and Ultrasonic ProcessingEmail: rtenaglia@ewi.orgPhone: 614.688.5241

New combinations of materials are being incorporated into designs of devices and structures to optimize performance and cost. Weight reduction, improved damage tolerance, life extension, ease of repair, material availability, and cost savings are some considerations in material selection. Material properties like corrosion and/or wear resistance, high-temperature strength, creep-rupture, thermal fatigue, and other specific mechanical and physical properties impact the function and performance of devices and structures. As designers work to meet competing cost and performance challenges, the application of dissimilar material combinations continues to increase. However, a key limitation in the application of many dissimilar material combinations is the ability to economically and reliably produce dissimilar material joints which meet performance goals.Mazda Motor Corporation developed direct spot joining technology to weld aluminum and steel. Friction stir welding was first employed in 2003 in the development of the Mazda RX-8 sports car, which used friction heat to join separate aluminum sheets. The technology evolved and was used to join the trunk lid and bolt retainer for the 2006 Mazda MX-5 sports car.

By optimizing the rotating tool shape and joining characteristics, and by using galvanized steel on one side, joining aluminum and steel is a practical feasibility.

Compared with conventional joining techniques such as riveting or clinching, spot friction welding makes it easier to join materials that are difficult to deform, such as aluminum castings and high tensile steel. Additionally, running costs can be reduced because riveting becomes unnecessary.The technology improves the potential of coupling aluminum parts to steel in vehicle bodies and helps lower the costs of production, Mazda says. The company adds that the technology contributed significantly to its vehicle weight reduction efforts during the development of the new MX-5, where each gram of weight shed was counted.Mazda Motor Corporation developed direct spot joining technology to weld aluminum and steel. Friction stir welding was first employed in 2003 in the development of the Mazda RX-8 sports car, which used friction heat to join separate aluminum sheets. The technology evolved and was used to join the trunk lid and bolt retainer for the 2006 Mazda MX-5 sports car.

By optimizing the rotating tool shape and joining characteristics, and by using galvanized steel on one side, joining aluminum and steel is a practical feasibility.

Compared with conventional joining techniques such as riveting or clinching, spot friction welding makes it easier to join materials that are difficult to deform, such as aluminum castings and high tensile steel. Additionally, running costs can be reduced because riveting becomes unnecessary.The technology improves the potential of coupling aluminum parts to steel in vehicle bodies and helps lower the costs of production, Mazda says. The company adds that the technology contributed significantly to its vehicle weight reduction efforts during the development of the new MX-5, where each gram of weight shed was counted.Mazda Motor Corporation developed direct spot joining technology to weld aluminum and steel. Friction stir welding was first employed in 2003 in the development of the Mazda RX-8 sports car, which used friction heat to join separate aluminum sheets. The technology evolved and was used to join the trunk lid and bolt retainer for the 2006 Mazda MX-5 sports car.

By optimizing the rotating tool shape and joining characteristics, and by using galvanized steel on one side, joining aluminum and steel is a practical feasibility.

Compared with conventional joining techniques such as riveting or clinching, spot friction welding makes it easier to join materials that are difficult to deform, such as aluminum castings and high tensile steel. Additionally, running costs can be reduced because riveting becomes unnecessary.The technology improves the potential of coupling aluminum parts to steel in vehicle bodies and helps lower the costs of production, Mazda says. The company adds that the technology contributed significantly to its vehicle weight reduction efforts during the development of the new MX-5, where each gram of weight shed was counted.Many applications for dissimilar materials joining have been for surgical tools, boroscopes and non-invasive diagnostics equipment such as remote sensors.

Applications being developed include disposable surgical tools for orthopedic procedures, joining stainless steel cutting edges to lighter, less expensive, non-invasive sections of the component. Other medical related components include sensor electrodes, boroscope windows and cutting-cauterizing electrodes.Oil and gas drillinguses smart drilling systems, containing dozens of sensors to regulate the speed, location and direction of a drill in order to permit the operators to guide the drill head to oil and gas deposits. The sensors and enclosures that protect the sensors require joining a range of dissimilar metals to a variety of ceramics. Additional applications in this market area include wear seals joining ceramics to metals.