High Strength Aluminium Fasteners G. Ross/R. Eul

Transcription

1 High Strength Aluminium Fasteners G. Ross/R. Eul

2 Content: TFS Key Facts Aluminium Fastener History Advantages & Benefits Applications Characteristics - Stress Corrosion Cracking - Fatigue Resistance - Relaxation Behaviour Manufacturing Process Current State of the Art - Customer Requirements - Achieved Product Performance Summary

3 TFS Key Facts World Headquarters: Troy, Michigan, USA Employees: Approximately 10,000 employees of which more than 54% are based outside of the United States Locations: More than 40 manufacturing locations in 17 countries Key Markets: Automotive, aerospace, construction, industrial, non-automotive transportation, and electronics Our Customers: Servicing our customers in more than 150 countries, they include GM, Ford and DaimlerChrysler, BMW, Boeing, Motorola, PSA, Volkswagen, HarleyDavidson, Hewlett-Packard, Delphi, Butler Building, Freightliner, and growing

4 TFS Product Offering TFS offers an extensive product portfolio in order to become a single-source supplier to its target customer base External Threaded $1067M (55%) TORX PLUS Mag-Form HangerMate PT Taptite Strux Machine Screws Engine bolts Tapping Screws SEMS Internal Threaded Nuts $143M (7%) Cage Nuts Threaded inserts Clinch Nuts High-Strength Hexert Rivtex Engineered Components $353M (18%) Cold Formed Specials Sheet Extrusions Intevia Assemblies Fine blankings Blind Fasteners $251M (13%) Speed Fastening Blind Inserts Breakstem Blind Rivets Aerospace Blind Fasteners Rivetless Nut Plate Installation Systems $34M (2%) Hand Tools Genesis Autoload Automated Assembly Systems Other Products $83.7M (4%) Metal Stampings Plastic retainers $1.932B 2004 Revenues RIPP

5 Aluminium Fastener History at TEXTRON Over 50 years experience, manufacturing Blind Rivets and Lockbolts made from AW2024, AW5019, AW5022, AW6061. Cold formed specials at Schrozberg plant made from AW6082, AW5019 as standard product range Screws made from AW7075 u. AW6063 globally circa 1995 first activities developing high strength Aluminium fasteners for Magnesium & Aluminium gearbox applications circa 2000 TEXTRON started to concentrate on material types AW6013 und AW6056

6 Related Standards DIN EN 515 Wrought Products; Temper Designations DIN EN Mechanical Properties of Fasteners ; Bolt, Screws Studs & Nuts made of Non-Ferrous Metals DIN EN Aluminium and Aluminium Alloys-Drawn Wire; Part 1: Technical Conditions for Inspection and Delivery DIN EN Part 2: Mechanical Properties DIN EN Part 3: Tolerances on Dimensions DIN EN Aluminium and Aluminium Alloys - Drawing Stock; Part 1: General Requirements and Technical Conditions EN Chemical Composition and Form of Wrought Products

7 Advantages of Aluminium Fasteners Weight reduction of about 65% due to reduced material density Example: Panhead ITX, M8 X 40 Weight Aluminium Version 6,5g Weight Steel Version 18,7g Weight Reduction 65% per piece Saving design room due to similar mechanical properties ca. 3xd 1xd Design follows the principle that fastener is the weakest part in the joint!

8 Advantages of Aluminium Fasteners Impressive reduction of Relaxation Behaviour at higher temperature, compared to steel fasteners Remaining Clamp load after temperature load and cooling down to room temperature Increasing temperature will provide additional clamp-load which will result in plastic deformation within fastener and specimen under head bearing area. In result the remaining clamp load of a steel fastener will fall below that of an equivalent Aluminium fastener.

9 Advantages of Aluminium Fasteners Reduced galvanic corrosion sensitivity against typical charges of joints with Aluminium and Magnesium specimens Steel 8.8 within Mg-Alloy (AZ91) Due to high difference in the electrochemical potential Magnesium material will be consumed Aluminium within Mg-Alloy (AZ91) Balance in ECP makes the fastener perfect for use in Al / Mg joints, normally no coating needed

10 Applications Characteristics Stress Corrosion Cracking - Occurs in SCC sensitive materials in combination with tensile stress and the presence of a corrosive environment - Is a complex phenomenon where electrochemical, mechanical and metallurgical factors are synergistically involved - Is difficult to control therefore has to be prevented High resistance to SCC -no failure -no relevant reduction in tensile strength -no metallographic evidence of SCC 6000-er All 7049 T T T T T73 Moderate resistance to SCC -no failure - no relevant reduction in tensile strength -there is metallographic Evidence of SCC 2024 T T T74/T T74/T T T T76 Results from ESA (European Space Agency) Low resistance to SCC -failure occur during test -reduction of tensile strength -there is evidence of SCC from metallographic 2024 T3/T All 7075 T T T T T6 All alloys in the 6000-serial are high resistant against SCC 7XXX alloys with a special heattreatment (e.g. T 73) are also resistant, but: T 73 T 73 is an over-aging process with the result of decreasing mechanical properties and elongation after fracture

11 Applications Characteristics Grain structure is measured and described by ASTM E Most of the customers require for GS 3 (e.g. VW) Core Area (T6) Surface Area (T9) A defined grain structure and size has to be provided & observed to get the required mechanical properties, like: Cold Formability Fatigue Strength Tensile Strength Yield Strength

12 Applications Characteristics Temperature Resistance - An important point for the user is the bolt s creep resistance under temperature influence. - Bolts made of AW 6056 (6013) perfectly meet the customer demands. Festigkeit/Tensile Strength in MPa Warmauslagerung bei 150 C/therm ic exposure at 150 C Zeit in h/time in hours EN AW-7075 EN AW-6056 AW-7075: Tensile strength loss about 25% AW-6056 fully meets customer requirements, strength loss less than 10%

13 Applications Characteristics Influence of Ageing by Heating Time to Product Properties Screw Type: I-Torx-Panhead M8x40 T9 Yield Point Ultimate Strength Elongation After Fracture 100,00 % v o m % 8 h of -W 8h-Value e r t 80,00 60,00 40,00 20,00 120,00 115,00 110,00 105,00 100,00 95,00 90,00 85,00 Optimal ageing time will be at about 8-12 hours Extension of ageing process may slightly increase tensile strength; but result in significant loss elongation after fracture 80, , Ageing Warmauslagerungszeit by Heating Time in h [h]

14 Manufacturing Process Aluminium Fasteners require specific conditions compared to steel, to achieve a capable manufacturing process! Wire Packed Shipment Limited Storage Time (max. 6 month) Specified Delivery conditions (treatment, grain size, lubrication, ) Made from primary Aluminium Heading Typical progression design Non mixed manufacturing with steel allowed - steel chips on Al-surface will cause chemical corrosion Specific header lubricant to be used

15 Manufacturing Process Cleaning For Aluminium suitable cleaning detergent to be used (alkaline instead of acidic) Rolling Typical tool design recommended - adapted in- and outlet Specific Aluminium lubricant to be used Non mixed manufacturing with steel allowed - steel chips on Al-surface will cause chemical corrosion Heat Treatment Critical process, requires precise temperature and time adjustment Main influence to product performance - Tensile strength - Yield Point - Elongation after Fracture - Relaxation Behaviour

16 Current State of the Art Customer Requirements (Standards) TEXTRON Ultimate Tensile Strength [MPa]: Yield Point [MPa]: min. 350 min. 350 Elongation after Fracture [%]: min. 4 min. 7 Fatigue Strength [MPa]: min Friction Coefficient [total]: 0,09-0,15 0,09-0,15 Grain Size [ASTM]: min. 2,5-3,0 3 Material Type : AL9 (6013/6056) AW 6056 Temperature Resistance over [1000 h at 150 C] max. drop in strength 10% < 10%

17 Current State of the Art Product Performance - Tensile Test M 8x40 Panhead I-TORX Material: AW 6056 T9 Results: Nr S0 L0 Rp 0,2 Rm mm² mm N/mm² N/mm² max min , ,02 427, , ,12 437, , ,95 431, , ,35 422,6 5 36, ,89 425,3 Statistics: Serie S0 L0 Rp 0,2 Rm n = 5 mm² mm N/mm² N/mm² x 36, ,66 429,04 min 36, ,35 422,6 max 36, ,12 437,94 Kraft-Spannung Tensile in N/mm² Strength [%] Elongation Dehnung in [%] %

18 Current State of the Art Product Performance Fatigue Test Test procedure according to DIN 969 M 8x40 Panhead I-TORX Material: AW 6056 T9 Kraftamplitude F sa = σm x A d3 (Abweichung siehe DIN 969) 1 2 Bruch kein Bruch (N min = 10 7 Lw) Mean Strength: σ m =266 MPa Probability of Survival: σ A 10%= 41,25 MPa σ A 50%= 37,50 MPa σ A 90%= 33,75 MPa N/mm² Lastspielzahl in Summe der Spalten Achieved results exceed current customer expectation of min. 15,00 MPa б = 30 [N/mm²] d = 5 [N/mm²]

19 Current State of the Art Product Performance Friction Coefficient M 8x40 Panhead I-TORX Material: AA 6056 T9

20 Current State of the Art Process Optimization by F.E. Simulation System in use: MSC Superform

21 Product Samples at TEXTRON Kepla-Coat by AHC hard coating (oxidation) + paint

22 Summary Application of Aluminium Fasteners within Automotive light weight design will provide major technical improvements, like: Weight reduction Constant and remaining clamp load Reduced galvanic corrosion The selection of: The optimal material and deliverer The right way in heading & threading process The importance of the correct and controlled heat treatment process Are the challenges of the manufacturing process