Materials & lightweighting: strategies, applications, opportunities

Vehicles with lower greenhouse impact are one of the four mega-forces for change that will shake-up the automotive industry in the next 15 or 20 years. Along with digitalisation of automotive, new powertrain technologies and autonomous vehicles.

Why lightweighting matters right now

• Concern about greenhouse gases is growing. More and more people are convinced that something needs to be done, and soon. Long-term, radically alternative powertrains and more efficient surface transport systems or self-driving cars may be a large part of the answer. But they are not the whole solution, and they are still too far way to make a big difference before the end of the next decade. At the same time, conventional powertrains may be subject to diminishing returns after the astounding efficiency gains of the last fifteen years.
• Lightweighting will have a key role in long term improvements in fleet energy consumption, whatever the powertrain solution or long term structure or organisation of the road transport fleet. But lightweighting will also be an important technology in the interim. Lightweighting is likely to be a growing part of the bridging solutions that enable more economy to be won from conventionally powered, traditionally set-up vehicles in the next ten years and beyond.
• Lightweighting is a key demand on the automotive industry that affects a huge range of products that are being designed now and in the near future. It is a trend that is important to OEMs, first and second tier suppliers,  as well as the materials suppliers themselves – with ramifications for the structure and skill-sets of the industry in the long term.

About the report

“Materials & lightweighting: strategies, applications, opportunities” explores technical and production features of a wide variety of new materials that carmakers are turning to in the effort to meet lightweighting goals. The report is a deep-dive that covers topics including technical, strategic and cost challenges in the application of materials such as high-tech steels, aluminum alloys, magnesium and titanium.

The report report answers technical questions, outlines the strategies for each OEM, and suggests opportunities for suppliers. It provides analytical comparisons of the use of materials from quality, manufacturing and cost perspectives, and includes 36 detailed company profiles.

Table of Contents

1. Introduction 12
Government policy initiatives 15
Weight based versus footprint based initiatives 20
Weight based 95 g/km target 22
Footprint based 95 g/km 23

2. Barriers to weight reduction 26
Product differentiation 26
Vehicle weight and safety 27
Improved vehicle dynamics and safety 30
Process development 31
Cost development 32

3. Sustainability considerations 33
Mass reduction and vehicle lifecycle CO₂ emissions 33
Case study Audi TT MY 2014 – 2015 36
End-of-life vehicles consideration 37

4. Historic perspective 41

5. Weight reduction by sector 48
Platform and module considerations 48
Body structure 52
Powertrain 54
Chassis 56
Interior developments 61

6. Materials technology 62
Steels 62
Steel industry global outlook 62
Advanced steel developments 63
Advanced alloy steels 68
Complex Phase steels (CP) 68
Dual Phase Steels (DP) 69
Ferritic-Bainitic Steel (FB) 70
Hot formed steel (HF) 70
Martensitic steel (MS) 71
Post forming heat treatable steel (PFHT) 71
Transformation-Induced Plasticity Steel (TRIP) 72
Twinning Induced Plasticity Steel (TWIP) 72
Boron UHSS 75
Special process steels 76
Evolving AHSS types 76
Three-phase steel with nano-precipitation 77
Quenching and partitioning 78
Competition from other materials 78

7. Steel forming technology 79
Hydroforming 79
Tailored blanks 79
Hot stamping 80
Zinc-Magnesium coated hot dip galvanised steel 82
Stainless steels for car frames 82

8. Aluminium alloys 84
Aluminium alloy systems 88
Wrought Alloy Series 89
Casting Alloys 92
Growth opportunities for aluminium 94
Powertrain applications 97
Chassis applications 100
Recycling 114

9. Magnesium 117
Magnesium versus aluminium 122
Price volatility 123
Demand for magnesium 127
Magnesium advantages 128
Magnesium extraction 131
Alloy and process development 132
Magnesium sheet production and stamping 137
Forging 139

10. Titanium 142
Titanium aluminides 144
Turbochargers 145
Titanium engine applications 146
Exhaust Systems 148
Titanium chassis applications 149
Brake Systems 149
Springs, bolts and fasteners 149
Lowering the cost of titanium 150
Extraction 150
Fabrication 150

11. Composite and Plastic Materials 153
Carbon Fibre 153
Types by raw materials: 157
Carbon fibre cost reduction 158
Process development 163
Thermocomposite materials 166
Thermoset versus thermoplastic 166
Plastics 169
Sheet moulding compound (SMC) 171

12. Nano-scale materials 173
Honeycomb structures 178

13. Hybrid materials technology 179

14. Bio-Materials 182
Challenges in bio-material application 183
Current and future applications 184
Textiles 188
Woven and knitted fabrics 188
Joining technology 191
Welding 191
Laser welding 191
Magnetic pulse welding 193
Plasma arc welding 194
Deformation resistance welding 195
Ultrasonic aluminium welding 195
Friction stir welding 197
Laser-Assisted Friction Stir Welding 198
Adhesive bonding 198
Hybrid bonding 201
Riveting 202
Self-piercing rivets 202

15. Company Profiles

Aapico Hitech Public Co.
Aichi Steel
Alcoa
Aleris
Amag Austria Metall
Arcelor Mittal
Basf
Benteler
CIE Automotive
Constellium
Faurecia
Georg Fischer
Gestamp
Gibbs Die Casting
GKN
Gurit
IMG
Iochpe Maxion
Kaiser Aluminium
Linamar Corporation
Luxfer Group
Magna
Martinea International
Meridian
Montupet SA
Novelis
Plastic Omnium
Shiloh Industries
Stemcor
Superior Industries
Tata Steel
Teijin
Thyssenkrupp
Tower International
Voestalpine
Yorozu Corporation

Table of Figures

• Figure 1: Characteristics of passenger cars and light-commercial vehicles (vans) in the EU: market share, vehicle mass, and vehicle size (footprint) 15
• Figure 2: 2012 performance of key EU passenger car manufacturers, including 2015 and 2020 (effectively 2021) target 16
• Figure 3: Average 2012 fuel consumption (in l/100 km, bold) and CO2 emission level (in g/km, in parentheses) of key EU passenger car manufacturers, including 2020 (effectively 2021) targets 19
• Figure 4: VW Golf evolution of kerb weight (kg) 1990 – 2015 21
• Figure 5: Options for a mass-based target system for reaching 95 g/km 21
• Figure 6: Effects of varying the emission target line slope (weight-based system) 22
• Figure 7: Options for a footprint-based target system for reaching 95 g/km 23
• Figure 8: Effects of varying the emission target line slope (footprint-based system) 25
• Figure 9: Issues that are barriers to weight reduction (LHS) 26
• Figure 10: Average kerb weight by segment MY 1990 – 2015 26
• Figure 11: A hybrid aluminium and advanced steel structure, Mercedes-Benz C-Class (2015) 27
• Figure 12: Relative CO2 reduction benefits vs relative cost 32
• Figure 13: The use phase dominates lifecycle vehicle emissions 33
• Figure 14: Analysing lifetime greenhouse gas effects 34
• Figure 15: Materials in body structure 2014 MY Audi TT 35
• Figure 16: Greenhouse gas emissions for various materials 35
• Figure 17: Materials evolution Audi TT MY2014 – 2015 36
• Figure 18: Greenhouse gas emission values for the entire lifecycle of the Audi TT Coupè 36
• Figure 19: Components in the Volkswagen Golf Mark 7 39
• Figure 20: Global automotive microelectromechanical systems (MEMS) sensors shipments 2010 – 2016 40
• Figure 21: Mini segment average kerb weights 1990 – 2015 (Europe) 41
• Figure 22: Lower mid segment average kerb weights 1990 – 2015 (Europe) 41
• Figure 23: Upper mid segment average kerb weights 1990 – 2015 (Europe) 42
• Figure 24: Luxury segment average kerb weights 1990 – 2015 (Europe) 42
• Figure 25: Average profit per vehicle versus CO2 compliance costs 43
• Figure 26: Progress in weight reduction through materials technology 43
• Figure 27: Trends in aluminium use 44
• Figure 28: Weight share of modules and their weight increase. 44
• Figure 29: The multi-material vehicle concept applied to the Audi A8 body-in-white 45
• Figure 30: PSA’s adjustable platform architecture 49
• Figure 31: Assembly kits in the Volkswagen Group 50
• Figure 32: Platform/ module evolution 2015 – 2020 51
• Figure 33: Changes in steel usage in BIW application 52
• Figure 34: Front bumper material and design for the Alpha Romeo Giulietta delivers 31 kg weight saving 53
• Figure 35: Estimated BIW materials composition 2006 and 2015 forecast 53
• Figure 36: Aluminium/ magnesium lightweight design 6 cylinder engine 54
• Figure 37: Engine weight and performance for aluminium and cast iron blocks 55
• Figure 38: Aluminium cylinder head with integrated exhaust manifold 56
• Figure 39: Areas for chassis weight reduction 57
• Figure 40: A lightweight strut with a fibreglass wheel carrier 58
• Figure 41: Range Rover magnesium front end structure 59
• Figure 42: Porsche 918 Spyder CFRP monocoque construction 59
• Figure 43: Alfa Romeo 4C carbon fibre production 60
• Figure 44: Mass reduction in seat design 61
• Figure 45: Apparent steel usage by region in 2015 62
• Figure 46: BIW materials by tensile strength BMW 6 Series 63
• Figure 47: Overall demand for auto steel and other metals and materials 65
• Figure 48: Advanced steel development expressed in terms of tensile strength 66
• Figure 49: VW changes in steel alloy use 2003 – 2015 68
• Figure 50: Microstructure of TRIP steel 72
• Figure 51: Advanced steel development for the future 75
• Figure 52: Use of boron steel in BMW’s 6 Series BIW 75
• Figure 53: Nanosteels’s nano-scale microstructure 76
• Figure 54: Nanosteel’s new class of AHSS materials 77
• Figure 55: Steel processing portfolio 80
• Figure 56: MagiZinc corrosion performance 81
• Figure 57: Aluminium content per vehicle (lbs 1975 – 2025) 84
• Figure 58: Aluminium content by component systems 85
• Figure 59: Average Al content by OEM for sample vehicles 2012 85
• Figure 60: Aluminium content increase (Kg) EU 2006 – 2012 86
• Figure 61: Aluminium and plastic componentry BMW 7 Series body structure 86
• Figure 62: Aluminium content in 2012 87
• Figure 63: Aluminium content change by vehicle segment (US) 87
• Figure 64: Iso-strength curves for 6000 Series alloys 91
• Figure 65: Composition of 7000 Series alloys 93
• Figure 66: Potential for aluminium extrusion use 94
• Figure 67: Aluminium content 2006 model and 2012 model 96
• Figure 68: Required aluminium additions to raise aluminium content by 40kg 97
• Figure 69: Automotive material distribution 2015 – 2025 97
• Figure 70: Federal Mogul’s Advanced Estoval II piston 99
• Figure 71: Aluminium steering knuckle 101
• Figure 72: BMW 5 Series with aluminium front and rear axle subframes 102
• Figure 73: Air suspension system components 105
• Figure 74: European aluminium direct weight savings and market penetration 2013 107
• Figure 75: European aluminium content (kg) D and E segment closures and body 109
• Figure 76: Cost of different aluminium structural body components 110
• Figure 77: Aluminium product forms in the Jaguar XJ (X350) 111
• Figure 78: Aluminium body of the Jaguar XJ (X351) 112
• Figure 79: Shift of materials applied for the Jaguar XJ: X350 – X351 113
• Figure 80: Aluminium recycling schematic 115
• Figure 81: Magnesium content per vehicle 117
• Figure 82: Single piece magnesium tailgate inner panel 118
• Figure 83: Specific strength versus specific stiffness for various materials 119
• Figure 84: Magnesium demand breakdown 121
• Figure 85: Lifecycle analysis of cast engine block for a vehicle life of 200,000 km 122
• Figure 86: Magnesium pricing history 123
• Figure 87: Global magnesium production 1998 and 2011 by region 124
• Figure 88: Die-cast magnesium motorcycle engine blocks 130
• Figure 89: A BMW magnesium cross-car beam giving a 50% weight saving over its steel fabrication alternative 131
• Figure 90: Cathodic poisoning to capture atomic hydrogen that otherwise is fundamental to the corrosion process 132
• Figure 91: Die cast V6 engine block 133
• Figure 92: AM-SC1 three cylinder engine block 134
• Figure 93: Stamped magnesium tailgate 135
• Figure 94: Thermally formed magnesium alloy sheet trunk lid inner 136
• Figure 95: Potential magnesium applications 137
• Figure 96: Potential magnesium extrusion use 138
• Figure 97: Turbocharger turbine wheel made from gTiAl 145
• Figure 98: Application of titanium-Metal Matrix Composite (MMC) alloys for engine components 146
• Figure 99: Connecting rod made of Ti-SB62 split using laser cracking 146
• Figure 100: Titanium MMC crankshaft using Ti-4A-4V+12% TiCl 147
• Figure 101: VW Golf 4-Motion titanium exhaust 148
• Figure 102: Comparison between titanium and steel spring showing 50% weight saving 149
• Figure 103: laser sintered complex titanium components 150
• Figure 104: Price elasticity of demand for various engineering materials 151
• Figure 105: Carbon fibre parts being moulded in BMW’s Leipzig plant 153
• Figure 106: Carbon fibre monocoque McLaren MP4-12C 154
• Figure 107: Density strength relationships for various engineering materials – composites 155
• Figure 108: Carbon fibre product types by mechanical properties 156
• Figure 109: The cost gap between aluminium and carbon fibre will decrease over time using an aggressive cost reduction scenario 159
• Figure 110: CFRP cost structure evolution 160
• Figure 111: Resin Transfer Moulding (RTM) process chain 162
• Figure 112: Resin Transfer Moulding (RTM) process schematic 162
• Figure 113: McLaren’s MP4-12C featuring a carbon fibre monocoque safety cell 163
• Figure 114: a schematic roadmap of CFRP future development 164
• Figure 115: Schematic of the Resin Spray Transfer process 165
• Figure 116: Advanced engineering plastics use in the Bayer demonstration vehicle 168
• Figure 117: Density strength relationships for various engineering materials – polymers 169
• Figure 118: Emerging automotive nanotechnology uses 173
• Figure 119: Nanocomposite interior component 175
• Figure 120: Bayer Carbon Nanotubes 176
• Figure 121: Over injection moulding of metal structures 179
• Figure 122: Optimised component design achieved by intrinsic materials hybridisation 179
• Figure 123: A schematic illustrating a holistic interdisciplinary approach to multi-material design and manufacture 180
• Figure 124: Optimal continuous fibre reinforcement design for thermoplastic component 180
• Figure 125: Hybrid materials process schematic 181
• Figure 126: Wheat Straw/ Polypropylene storage bin and cover liner used in the 2010 Ford Flex 185
• Figure 127: Joining technologies used in automotive manufacturing 191
• Figure 128: Laser welded door containing three different steels 192
• Figure 129: Friction stir welding 196
• Figure 130: Friction stir welding 197
• Figure 131: Laser assisted friction stir welding 198
• Figure 132: Blind rivets 202
• Figure 133: Tread forming screws 202
• Figure 134: Self-piercing rivets 203

Table of Tables

• Table 1: The relative cost of fuel economy measures – gasoline engines 12
• Table 2: The relative cost of fuel economy measures – diesel engines 13
• Table 3: 2012 performance of key EU passenger car manufacturers, including 2015 and 2020 (effectively 2021) targets 18
• Table 4: Sales/registrations-weighted averages per manufacturer in 2009 24
• Table 5: Changes in assessed sustainability categories Audi TT Coupè MY2014 – 2015 37
• Table 6: OEM statements and commitments to weight reduction 47
• Table 7: Multi-materials potential body applications 48
• Table 8: Fuel economy improvement and costs for powertrain 54
• Table 9: Weight reduction in lightweight shock absorber assemblies 56
• Table 10: Steel types used in automotive applications 67
• Table 11: Market penetration of BIW applications 2013 88
• Table 12: weight reduction versus the price increase by replacing steel by aluminium 2013 88
• Table 13: European aluminium content by sample vehicle 2012 95
• Table 14: Future aluminium content analysis 95
• Table 15: properties of magnesium alloys compared with plastics, steel and aluminium 120
• Table 16: Potential for weight saving replacing aluminium with magnesium in the powertrain 125
• Table 17: Mechanical and physical properties of Magnesium 129
• Table 18: Typical properties of TiAl based alloys compared with well known titanium alloys 144
• Table 19: Material comparison with carbon fibre 157
• Table 20: Carbon fibre cost trends 158
• Table 21: Material comparison with carbon fibre 158
• Table 22: A range of JVs between OEMs and carbon fibre producces 161
• Table 23: DoE US targets and metrics for carbon fibre and composites 166
• Table 24: Advantages and disadvantages of thermoset and thermoplastic composites 167
• Table 25: Thermocomposite materials 167
• Table 26: Emerging applications for carbon nanotube based materials technology 174
• Table 27: Mechanical properties of selected fibres and polymers 182
• Table 28: Bio-based content of selected automotive components 184
• Table 29: Selected bio-based automotive components 186