Progress of Research and Development ofMagnesium alloys on New Energy Vehicles inChina
Shi Wenfang, Wang Huaiguo
The Nonferrous Metals Society of China
Mao PingliShenyang University of Technology
November, 20181

Outline Research Background Magnesium smelting technology

 New Magnesium alloys development
 Fabrication Technologies of Magnesium alloys
 Evaluation Methods of Magnesium Development of Typical Magnesium components
 Integrated Application of Magnesium Components
 Development of Mg electric bus boy

 Challenges Faced with the Application of Mg

2

Research Background—Rich in natural resoures Magnesium is rich in natural resources
 China is a major producer and exporter of magnesium.

3Research Background—Lightweight
The lightweight advantage of magnesium has beenhighly valued by the world wide. And China is noexception

FeAlMg44

Research Background— Enviroment Protection
In October 2016, The Society of Automotive in China released “the technology
roadmap for energy saving and new energy vehicles” .
To fulfill the Energy-efficiency goal the technique roadmap require that: To the year of 2020, the application of magnesium alloy in a single car must
exceed 15Kg
 To the year of 2025, the application of magnesium alloy is 25Kg
 To the year of 2030, the application of magnesium alloy is 45Kg.

Magnesium
alloy

2020

2025

2030

The magnesium
consumption per vehicle isThe magnesium
consumption pervehicle is 25 kg.

The magnesium
consumption per vehicle
is 45 kg.

15 kg

5

Magnesium smelting technology
 Vertical tank reducing furnace heat accumulation combustion
technology
 Developed a novel heat accumulation combustion vertical tank reducing
furnace.
 The energy consumption was significantly reduced due to the compact
structure of the furnace and high density tank of the combustion chamberStandard coal consumption:less than 4.5 tons per ton Mg

NANJING YUNHAI SPECIAL METALS CO.,LTD

Magnesium smelting technology
 Bottom slag removal technology Recovery and purify technology of the smelting waste
 Low grade smelting waste vacuum distill technology

Has been widely used in magnesium smelting industry and greatly increases Mg
smelting efficiency

NANJING YUNHAI SPECIAL METALS CO.,LTD

Magnesium alloys development
 Fatigue-resistant cast magnesium alloy Magnesium alloy: Mg-8Zn-0.5Al-0.5Cu-0.5Mn; Mg-8Zn-1Al-0.5Cu-0.5Mn ;Mg-6Zn-1Al-0.5Cu-0.5Mn
 After two-stage aging, the mechanical properties: σb≥300MPa, σ0.2≥205MPa, δ≥10%.
 Fatigue property: Mg-8Zn-1Al-0.5Cu-0.5Mn alloy, the fatigue strength is higher than
90MPa (5×107)

Mg-8Zn-1Al-0.5Cu-0.5Mn Mechanical properties of alloy at room temperature
Extensibility（AlloyStatus%）
Mg-8Zn-0.5Al0.5Cu-0.5Mn
Mg-8Zn-1Al-0.5Cu0.5Mn
Mg-6Zn-1Al-0.5Cu0.5Mn

T6213.0312.6

10.9

T6

228.0

328.0

14.7

T6

208.3

309.1

10.9

Fatigue performance test results of Mg8Zn-1Al-0.5Cu-0.5Mn alloy

Institute of Metal Research, Chinese Academy of Sciences

8

Magnesium alloys development
 Impact-resistant cast magnesium alloy
The developed Mg-4Zn-3Y-0.3Zr alloy, after T4 or T6 treatment, the staticmechanical properties: σb ≥ 250MPa, σ0.2 ≥ 170MPa, δ ≥ 15%, and at high strain rate
(The strain rate is 500～4000s -1 ), δ≥10%, and the performance meets therequirements of the assessment index.
350

Mg-4Zn-3Y0.3Zr

T4270℃ aging
320℃ aging

162.4
181.6
178.7

231.5
254.2
250.3

14.3
15.5
15.7

300

stress,MPa

Mg-4Zn-3Y Mechanical properties of heat-treated alloys
Processingd5（%）
Alloy
state

250-1

2789s
-1
2358s
-1
2005s

200
150
10050

Impact compression-strain curve of Mg4Zn-3Y-0.3Zr alloy (as cast)

00.00

0.04

0.08

0.120.16

srain

Shenyang University of Technology

9Magnesium alloys development
 High plasticity magnesium alloy
 Several low-cost and high plasticity deformation magnesium alloys have beendeveloped The room temperature mechanical properties: σb≥250MPa, σ0.2≥190MPa, δ≥20%.
 Mg-1Al-1Sn alloy is equivalent to AZ31 alloy in deformation ability. After hotextrusion at 300oC, the mechanical properties: σb≥280MPa, σ0.2≥230MPa, δ≥22%.
High plasticity Mg alloys

Main feature

Market Price(ten-thousand)cost

Mg-2Zn-Mn-(0.2-0.6)Ce

High plasticity
medium strength

2.3-3.2

5% higher than AZ31

Mg-0.3Zr-2Zn

Medium strengthand ductility

2.5-3.5

15% higher than AZ31

Mg-1Al-1Sn

Better strengthand ductility

2.1-2.9

Equal to AZ31

Harbin Institute of Technology

10Magnesium alloys development
 Creep and heat resistant cast magnesium alloy
 Developed GW83 alloy Mechanical properties after die casting and heat treatment: σb 310MPa, σ0.2230MPa, δ 9%.

 200oC high temperature mechanical properties: σb 280MPa, σ0.2 225MPa, δ 20.5%.
 Creep properties: 200 oC at 70MPa, the total creep of 100 hours is about 0.0036%.
It is showing good creep resistance.

Creep curve of peak aged GW83 alloy

Shanghai Jiao Tong University

11Magnesium alloys development
 High strength wrought magnesium alloy
 High-strength wrought magnesium alloy EW75M with density of 1.92g/cm3
 RT mechanical properties after a invented whole set treatment technology:
σb ≥ 470 MPa, σ0.2 ≥ 390 MPa, δ ≥ 7%.

Multi direction forging+ direct extrusion

General Research Institute for Nonferrous Metals (GRINM)

12

Magnesium alloys development
New die-cast magnesium alloy Three types of die-casting magnesium alloys, Mg-Al-Sn, Mg-Sm-Zn and Mg-NdZn alloys, were developed.
 The effects of alloying elements on microstructure and properties were studied.
 The composition range, casting process parameters and heat treatment processparameters were optimized for the alloys

The composition of AT72 alloy
is lower than that of AZ91, but its
strength is similar to that of AZ91.,
The plasticity is improved bynearly 2 times, showing excellent
comprehensive performance.

Die castingalloyYield
tensileElongation(%)
Strength(MPa) strength(MPa)

Mg-9Al-6Sn

154

230

3.4

Mg-7Al-2Sn
AZ91
AM60
AM50
AS41
AE42131130115
105
150
110

227
230
205
207
220
244

8.5
366412

Shanghai Jiao Tong University13Fabrication Technologies of Magnesium alloys
 High Vacuum die casting technology
 High vacuum die casting system was designed.
 The vacuum pressure less than 5 kPa can beachieved within 1.5 seconds under actual castingconditions.
 The mechanical properties is increased and theporosity is decreased

vacuum pressure

Vacuum valve pressure curve under
actual vacuum die casting conditions

1103230
Tsinghua University
Test Date: Nov.30,2011
Test Die: Mechanical Property Test Die
HVV+Normal Plunger
Test Condition: Vacuum Casting Condition
Alloy: JDM3Slow shot speed: 0.40 m/s improved

Porosity distribution

Vacuum Pressure(kPa)9080706024222018141240

10308620410Tsinghua UniversityShenyang University of Technology

2616Valve pressure
Cylinder Pressure

5028

Cylinder Pressure(MPa)100200123

45Time(s)

67890
1014

Fabrication Technologies of Magnesium alloys
 Large size billet semi-continuous casting technology
 Large size flate billet was fabricated by semi-continuous casting technology.
 The semi-continuous casting process was optimizedin based on the analysis of flow
and temperature field.
 The large size of 850mm  850mm 350mm flat billet of AZ31B magnesium alloy
was successfully fabricated.

AZ31Bmagnesiu
m alloy

850mm850mm x350mm flat billet

North East University

15

Fabrication Technologies of Magnesium alloys
 Wide sheet rolling technology
 Maximum width of 1600mm, a thickness range of 8mm-100mm medium plate Maximum width of 1500 mm and a minimum thickness of 1.0mm.
 The maximum coil weight is 1000kg.
 Mechanical properties of AZ31B sheet: σb = 282MPa, δ = 20.5%.

A magnesium alloy wide sheet rolling production line,with an annual production capacity of 2,000 tons.
Wide-width plate heavy reduction

Shanxi Wenxi silver light magnesium industry (Group) Co., Ltd16

Fabrication Technologies of Magnesium alloys
 Magnesium alloy sheet strip casting and rolling technology
 Developed a Low-cost,high-efficiency cast rolling technology
 Have the ability to supply the production of cast rolling sheet with width of 800mm
and thickness of 2.5-8mm, sheet coils with thickness of less than 4mm and finishingrolling sheet coils with thickness of 0.3-2.5mm.
 Mechanical properties of typical AZ31B magnesium alloy: σb 250MPa, δ 25%, yield tostrength ratio  0.4.

Production line withan annual production
capacity of 1,000
tons of cast rolling
sheet

North East University17

Fabrication Technologies of Magnesium alloys
 Extrusion-rolling technology for Mg alloy strip
 The thickness of Mg alloy strip is 0.6mm, width of 500mm.
 Single roll weight is 300kg

 Mechanical properties: σb=356MPa, δ=21%, sheet anisotropy factor r =1.07
Built a strip production line with the annual capacity of more than 1,000 tons

Magnesium strip rolling lineMagnesium strip roll

Shanxi Wenxi silver light magnesium industry (Group) Co., Ltd18

Fabrication Technologies of Magnesium alloys
 Wide-width thin-walled hollow Mg profile technology
 A Mg profile product for high speed trains was successfully fabricated.
 The profile with the circumcircle diameter of 504 mm, the wall thickness of 1.8-3.5mm and length of 15m and more;the tensile strength of the profile is 258 MPa and the elongation is 11%.
Mg profile
product for highspeed trains

4500 tons extrusion production line

University of Chongqing

19

Fabrication Technologies of Magnesium alloys
 Wide-width thin-walled hollow Mg profile straightening
technology
 Combined using medium-temperature tension straightening technology and pressure
and torsion straightening technology.
 Built a digital control special device for magnesium alloy profiles.
 The bending of the product is controlled less then 1.5mm/m, and minimum value isless then 0.5mm/m.
 It was sucessfully used in Boeing guide rail straightening.
Boeing guide rail
Straightening production line

University of Chongqing

20Fabrication Technologies of Magnesium alloys
 Continuous high-speed casting and extrusion technology
 Developed a continuous high-speed casing and extrusion technology for Mg alloys.
 For rods with a diameter of Φ8-20mm, the speed is up to 30m/min; For wires with a diameter of 2-4mm, the speed is up to 40m/min.

Wire production

North East University

The equipment

21

Fabrication Technologies of Magnesium alloys
 Magnesium alloy friction stir welding technology
 Friction stir welding (FSW) technology was developed for the similar magnesium
alloys and dissimilar magnesium alloys with different welding speeds and different

plate thicknesses.
 The fatigue performance of AZ31 FSW joint at high speeds was found to be better thanthat at low speeds Two 1000 mm × 500 mm × 5 mm magnesium alloy sheets were successfully weldedby FSW, and the maxium deformation is less than 3mm/m2
FSW
Sheet before weld

AZ31 FSW joint fatigue performance

Institute of Metal Research, Chinese Academy of Sciences

Sheet after weld
22

Evaluation Methods of Magnesium Durability evaluation
 The uniaxial fatigue life of three types of welded joints (FSSW, TIG, FSW) of fouralloys (AZ31, AZ91, AM60, and ZACM) was evaluated.
 The fatigue life of ZACM alloy FSW joint exceed 1107 cycle when the stressamplitude is 80MPa.
 The fatigue crack originates from the subsurface of the specimen and expands along
the weld zone.

ZACM casting alloy

Institute of Metal Research, Chinese Academy of Sciences

23

Evaluation Methods of Magnesium Crashworthiness evaluation
Split Hopkinson Pressure Bar(SHPB) was used toevaluate the crashworthiness of Mg alloys.
Tested materials: vacuum die-casting AM60B; diecast AT72, as-rolled AZ31 and extruded MgGdY alloy.
The joint of AZ31 alloy was also evaluated after FSW.

400

specialTIG

400200-1950s-11520s-12170s-12300s-12451s

10000.00

0.05

0.100.15

True stress/MPa

True stress/MPa300

300200FSW-1940s-11838s-12253s-12343s-12797s

10000.00

True strain

0.05

0.100.15

True strain

Rolled AZ31 alloyShenyang University of Technology

24Evaluation Methods of Magnesium
Institute of Metal Research,
Chinese Academy of Sciences Corrosion Protection Evaluation

Xi’an University ofTechnology MAO(micro-arc oxidation) + electrophoretic coating, MAO + electrostatic spray coating

 MAO + inorganic sealing Self-sealing MAO coating
 MAO nano-self-assembled composite coating
Corresion Rate of Mg / mm/year

6MountingCompoundPowdercoat
MAO
CoatSubstrate

MAO+ electrostatic spraying
Coating surface and surface morphology

MAO+ electrostatic spraying
wheel

55.1
AZ31B Substrate
MAO
MAO+Sol
MAO+ED
MAO+Powder

432
1
0.4

0.38

0.3
0.2

0.16

0.1

0.005

0.004

0.0

Average corrosion rate of different
treated magnesium alloys
25

Development of Typical Magnesium components Steering gear Housing
Cadillac CTS engine bracket designed with CAE and manufactured with high vacuum
die-casting technology. When the vacuum is 5KPa, the porosity is as low as 0.05%.

a）5KPa； b）20KPa；c）50KPa; d）100KPa

Shenyang University of Technology

X-Ray detection

26

Development of Typical Magnesium components
 Volvo Central console bracket
 Material: AZ91
 Design: CAE

 Technology: Vacuum die-casting. The weight of single-mode casting is 5.9 kg,
the projected area of parts is about 0.4m2, the parts porosity is less than 1.5%.

Simulation

Chongqing Boao Industrial Co., LtdCasting: One mold two pieces27

Development of Typical Magnesium components
 Steering column bracket (ROEWE 750)
 Material: AZ91
 Design: CAE, Topological optimization technology. a reinforced rib structure
was designed to replace the think well structure where it bear weak stress Technology: Sand casting: pouring temperature 700℃, sand baking temperature:200℃; graphite coating, coating thickness 0.5 mm.

Shenyang University of Technology28

Development of Typical Magnesium components
 Magnesium wheel(ROEWE 750)
 Material: ZM203, JDM-1 alloy two materials
 Design: CAE analysis; Technology: low pressure casting, gravity casting.

Wheel radial fatigue test stress map

Shanghai Jiao Tong University29

Integrated Application of Magnesium Components
 ROEWE 750 PLUG-IN Fuel-cell vehicle

Shanghai Motor Co., LtdSynchronized with ROEWE 750PLUG-IN fuel cell sedan, 10 kinds of typical magnesium
alloy components were developed. The total weight is more than 100Kg; sampling performanceof typical parts is: σb=350MPa, δ=20%.
Magnesium alloy is 100Kg
Among them, wrought magnesium alloyis 35.727Kg

PLUGIN fuelcellsedan30Integrated Application of Magnesium Components
 Karting racing car
13 kinds of typical magnesium alloy parts with the total weight of 8.73Kg
were developed for K-JSA, K-JSB and K-JSC karting racing cars. The lightweight ratio is 6.8%. The racing cars passed the collision and road test.

K-JSC Karting Racing
car on the track

Collision test31

Development of Mg electric bus boy
 development of high performance profile

MeltingCasting

ZTM Mg alloy
profilesHeat treatment

Extrusion32

Development of Mg electric bus boy
 development of high performance profile A rapid extrusion technology was developed.
 This technology reduce the energy consumption of the equipment
and increase the life of the extrusion cylinder significantly.
 A total of 23 kinds of magnesium alloy profiles were prepared bythis technology, and the extruded product rate is ≥90%.
 After the surface treatment of the profile paint, the neutral salt
spray corrosion test reached 9 grades over 800h, and the coating
adhesion reached 0 grade.

Mechanical Properties• UST＞350MPa• YS＞280MPa• d＞10%。

33

Development of Mg electric bus boy
 development of high performance profile
Developed a fluorine and chrome freephosphating technology, and it was
successfully applied in the Riveting between
Mg alloy and 6082 Al.

Mg

AlMAO of Mg-Al joint
Riveting between
Mg alloy and 6082
Al profile

polarization curve
34Development of Mg electric bus boy
 Development of Mg Bus body
Body stiffness analysis (CAE)
Vertical bend condition• Low temperature fast extrusion
technique for Mg alloy profile• High performance Mg alloy
profile• Mg-Al joining technique
Max deformaiton:26.48mm
Front left wheel suspend condition• Surface protection technique forMg profile.

Application of Mg alloy inthe bus body is 226Kg.
Compare with the steel andaluminum body, the lightweight is 780Kg and 110Kg,respectively. And the lightweight ratio is 70% and 30%,respectively.

Max deformaiton:33.05mm
Right sharp turn condition

Max deformaiton:28.05mm

Magnesium bus body

Magnesium bus demo35

Challenges Faced with the Application of Mg
Take the advantages of materials and technology
Most experts thought that the fundamental way to solve the problems ofenvironment protection and energy shortage is to develop the electrical vehicle.
However, the weight increased by battery is an inevitable problem faced with EV.
Then the questions is: how can we take the advantage of lightweight given by
light metal, such as Mg, Al, Ti, ect., but avoid the drawback of weight increasing
by battery?.

36

Challenges Faced with the Application of Mg
Let the proper materials play its own roles in proper filed

Strategies and methods to increase Mg application in automobile(Volkswagen Development Center)37

38