AHS Steels for Automotive Parts Asst. Prof. Vitoon Uthaisangsuk, - - PowerPoint PPT Presentation

▶
ahs steels for automotive parts
SMART_READER_LITE
LIVE PREVIEW

AHS Steels for Automotive Parts Asst. Prof. Vitoon Uthaisangsuk, - - PowerPoint PPT Presentation

Jul 19, 2023 12 likes •1.03k views

20-21J 20 21June 2013 une 2013 BITE BITEC, B , Bangk angkok ok -Thailand hailand AHS Steels for Automotive Parts Asst. Prof. Vitoon Uthaisangsuk, Dr.-Ing. Department of Mechanical Engineering, Faculty of Engineering King Mongkuts

slide-1
SLIDE 1

AHS Steels for Automotive Parts

  • Asst. Prof. Vitoon Uthaisangsuk, Dr.-Ing.

Department of Mechanical Engineering, Faculty of Engineering King Mongkut’s University of Technology Thonburi (KMUTT)

1

20 20-21J 21June 2013 une 2013 BITE BITEC, B , Bangk angkok

  • k -Thailand

hailand

slide-2
SLIDE 2

Outline

  • Automotive evolution
  • Car body structures
  • Automotive steels
  • Mild steels
  • High strength steels
  • Multiphase steels
  • Press hardened steels

2

slide-3
SLIDE 3

Outline

  • Automotive evolution
  • Car body structures
  • Automotive steels
  • Mild steels
  • High strength steels
  • Multiphase steels
  • Press hardened steels

3

slide-4
SLIDE 4

Materials used for car components - 1975

Source: Ducker Worldwide

Average 1975 vehicle weight

4

slide-5
SLIDE 5

Source: Ducker Worldwide

Materials used for car components - 2007

Average 2007 vehicle weight

5

slide-6
SLIDE 6

Source: Ducker Worldwide

Trend of materials usage

6

slide-7
SLIDE 7

Source: WorldAutoSteel

Aim of automotive industries (mass reduction)

7

slide-8
SLIDE 8

Aim of automotive industries (mass reduction)

Source: WorldAutoSteel 8

slide-9
SLIDE 9

Source: WorldAutoSteel

Aim of automotive industries (mass reduction)

9

slide-10
SLIDE 10

Role of HSS and AHSS for vehicle mass reduction

10

slide-11
SLIDE 11

Growth of AHSS

11

slide-12
SLIDE 12

Increasing of safety regulations

12

Evolution of North America crash tests

slide-13
SLIDE 13

13

Safety concept

slide-14
SLIDE 14

14

Safety concept

Source : http://www.autosteel.org

slide-15
SLIDE 15

Safety concept

15

slide-16
SLIDE 16

16

Safety concept

slide-17
SLIDE 17

17

Strength comparison AHSS vs conventional HSS

Component material strength

DP 350/600 HSLA 350/450

Yield strength (MPa)

slide-18
SLIDE 18

Conflict between mass reduction & safety regulations Fuel economy / CO2 emissions

  • Lower weight / lighter gauges

Safety

  • Higher strength / heavier gauges

Conflict between safety & fuel economy / CO2 emissions Seeking of new challenging materials and manufacturing concept

18

slide-19
SLIDE 19

Outline

  • Automotive evolution
  • Car body structures
  • Automotive steels
  • Mild steels
  • High strength steels
  • Multiphase steels
  • Press hardened steels

19

slide-20
SLIDE 20

Steel sheet concept for automotive parts

Source : http://autospeed.com/cms/title_Steel-Identification-Using-Hardness-Testing/A_109717/article.html

20

slide-21
SLIDE 21

Source : http://mercedes-benz-blog.blogspot.com/2010/03/new-mercedes-benz-e-class-cabriolet_2785.html

2010 The new Mercedes-Benz E-Class

21

Steel sheet concept for automotive parts

slide-22
SLIDE 22

Source : http://boronextrication.com/tag/list-of-vehicles-with-boron-and-uhss

2011 Volvo V70 Body Structure

22

Steel sheet concept for automotive parts

slide-23
SLIDE 23

23

Source: http://carskeleton.blogspot.com/2012_04_01_archive.html

Steel sheet concept for automotive parts

2012 Audi A3 body Structure

slide-24
SLIDE 24

Source : http://www.autosteel.org

24

Steel sheet concept for automotive parts

slide-25
SLIDE 25

25

Source : http://www.autosteel.org

Steel sheet concept for automotive parts

slide-26
SLIDE 26

Cold rolled steels

26

slide-27
SLIDE 27

Overview of cold rolled steel sheets

27

slide-28
SLIDE 28

28

Strength evolutions of automotive steels

Source: http://www.metalformingfacts.com/industry-news/developments-gigapascal-strength-steels.html

slide-29
SLIDE 29

Outline

  • Automotive evolution
  • Car body structures
  • Automotive steels
  • Mild steels
  • High strength steels
  • Multiphase steels
  • Press hardened steels

29

slide-30
SLIDE 30

Mild steels

30

Best formability High and Ultra high strength steels

slide-31
SLIDE 31

Mild steels

31

slide-32
SLIDE 32

Mild steels for cold forming

32 max. C P S Mn Ti Al Si N DC04 0,08 0,030 0,030 0,40

  • 0,040

0,010 0,005 max. C P S Mn Ti Al Si N DC04 0,08 0,030 0,030 0,40

  • 0,040

0,010 0,005 >0,18 n90 value >1,6 r90 value YS MPa UTS MPa A 80% Ag % 140-210 270-350 >38% ~22 >0,18 n90 value >1,6 r90 value YS MPa UTS MPa A 80% Ag % 140-210 270-350 >38% ~22 Microstructure:

  • ferritic matrix
  • Carbides (few) and AlN

Mechanical properties:

  • Low yield strength and tensile strength
  • Low hardness
  • Very high total elongation
  • Great ductility and draw-ability

Specified value Typical value Specified value Typical value

slide-33
SLIDE 33

Mild steels for cold forming

33 Microstructure:

  • Ferritic matrix
  • Precipitates (few) of micro-alloyed

elements Mechanical properties:

  • Low yield strength and tensile strength
  • High n-value
  • High r-value
  • High uniform elongation
  • Great ductility and draw-ability

max. C P S Mn Ti Al Si N DC06 0,02 0,020 0,020 0,25 0,3 0,040 0,010 0,002 max. C P S Mn Ti Al Si N DC06 0,02 0,020 0,020 0,25 0,3 0,040 0,010 0,002 >0,22 n90 value >2,1 r90 value YS MPa UTS MPa A 80% Ag % 140-170 270-330 >41% ~25 >0,22 n90 value >2,1 r90 value YS MPa UTS MPa A 80% Ag % 140-170 270-330 >41% ~25 Specified value Typical value Specified value Typical value

slide-34
SLIDE 34

Outline

  • Automotive evolution
  • Car body structures
  • Automotive steels
  • Mild steels
  • High strength steels
  • Multiphase steels
  • Press hardened steels

34

slide-35
SLIDE 35

High strength steels

35

slide-36
SLIDE 36

Increasing strength of steel sheets

36

slide-37
SLIDE 37

High strength steel by solid solution strengthening

37

slide-38
SLIDE 38

Solid solution strengthening (mixed crystal strengthening)

38

slide-39
SLIDE 39

Influence of alloying elements on the yield point

substitutionally dissolved: P, Si, Cu, Mn, Mo, Ni, Al, Cr and interstitially dissolved: C, N

39

slide-40
SLIDE 40

High strength steels by precipitation strengthening

Formation

40

slide-41
SLIDE 41

Increasing the yield point of a-iron through different types of precipitations

41

slide-42
SLIDE 42

HS steels by work hardening (dislocation strengthening)

42

slide-43
SLIDE 43

Dislocation density as a function of amount of deformation in pure iron

Degree of deformation

43

slide-44
SLIDE 44

Evolution of dislocation structure in deformed tensile samples

44

The area next to the Lüders band is nearly without dislocation Dislocation in the area

  • f uniform elongation

Cell structure nearby fracture

slide-45
SLIDE 45

Conventional high strength steels: Micro alloyed steels

45

slide-46
SLIDE 46

Micro alloyed steels: alloying concept

46

slide-47
SLIDE 47

Metallurgical process during hot rolling

47

slide-48
SLIDE 48

Micro alloyed steels: properties, typical applications

48

slide-49
SLIDE 49

HSLA steels

49 Microstructure:

  • Ferritic microstructure with a little pearlite
  • Precipitates of micro-alloyed elements

Mechanical properties:

  • High yield strength
  • High tensile strength
  • Limited draw-ability and stretch-ability

max. C P S Mn Ti Al (min) Si Nb HX340LAD 0,11 0,030 0,025 1,00 0,15 0,015 0,50 0,09 max. C P S Mn Ti Al (min) Si Nb HX340LAD 0,11 0,030 0,025 1,00 0,15 0,015 0,50 0,09 ~0,14 n90 value ~1,0 r90 value YS MPa UTS MPa A 80% Ag % 340-420 410-510 >21% ~14 ~0,14 n90 value ~1,0 r90 value YS MPa UTS MPa A 80% Ag % 340-420 410-510 >21% ~14 Specified value Typical value Specified value Typical value

slide-50
SLIDE 50

Conventional high strength steel: High strength IF steels

50

slide-51
SLIDE 51

High strength IF steels: alloying concept

51

slide-52
SLIDE 52

High strength IF steels: properties, typical applications

52

slide-53
SLIDE 53

Conventional high strength steels: Bake hardening (BH) steels

53

slide-54
SLIDE 54

Schematic diagram of the bake hardening effect, by example of the production of a car door

54

slide-55
SLIDE 55

Increasing strength by bake-hardening

55

slide-56
SLIDE 56

Bake-hardening behavior of different steel grades

56

slide-57
SLIDE 57

Bake-hardening steels: properties, typical application

57

slide-58
SLIDE 58

Outline

  • Automotive evolution
  • Car body structures
  • Automotive steels
  • Mild steels
  • High strength steels
  • Multiphase steels
  • Press hardened steels

58

slide-59
SLIDE 59

Metastable iron - carbon (Fe-C) phase diagram

10 20 30 40 50 60 70 80 90 100 1 2 3 4 5 6 7 L Q P S O G K F D C E N B A I 500 600 700 800 900 1000 1100 1200 1300 1400 1500 1600 M

L + Fe C

3

L H

Fe 3C (Cementite)

L + 

L +  + Fe C

3

 + Fe C

3

a

a

a   

Cementite content in mass % Carbon content in mass % Temperature in °C

Source: Pitsch, W.; Sauthoff, G.; Hougardy, H.P. in: Werkstoffkunde Stahl, Band 1: Grundlagen, Verein Deutscher Eisenhüttenleute, Springer-Verlag 1985

59

slide-60
SLIDE 60

Transformation-Temperature-Time (TTT) diagram

60

slide-61
SLIDE 61

Austenite

61

slide-62
SLIDE 62

Bainite – Ferrite - Martensite

62

slide-63
SLIDE 63

Polymorphism of iron

63

slide-64
SLIDE 64

Mechanical properties of different phases in steels

Phase Re , MPa Rm, MPa A, % Hardening, HV Interstitial free condition (Ferrite) 100-150  280  50

  • Ferrite (unalloyed)

Ferrite (0,7% Ni, 0,6% Cr) Ferrite (13% Cr) 220 330 300 300 550 500 45 35  18

  • about 180
  • Pearlite

 900  1000  10

  • Cementite

 3000

  • Bainite ( 0,1% C)

400-800 550-1200  25 about 320 Martensite ( 0,1% C) Martensite ( 0,4% C) 800 2400 1200

  • 5
  • about 380
  • Austenite (18% Cr, 8% Ni)

 300  600  40

  • Phase

Re , MPa Rm, MPa A, % Hardening, HV Interstitial free condition (Ferrite) 100-150  280  50

  • Ferrite (unalloyed)

Ferrite (0,7% Ni, 0,6% Cr) Ferrite (13% Cr) 220 330 300 300 550 500 45 35  18

  • about 180
  • Pearlite

 900  1000  10

  • Cementite

 3000

  • Bainite ( 0,1% C)

400-800 550-1200  25 about 320 Martensite ( 0,1% C) Martensite ( 0,4% C) 800 2400 1200

  • 5
  • about 380
  • Austenite (18% Cr, 8% Ni)

 300  600  40

  • 64
slide-65
SLIDE 65

Homogeneity of grain structure - properties

65

slide-66
SLIDE 66

Characteristics of AHSS

66

slide-67
SLIDE 67

Microstructures of modern multiphase steels

Higher strength

67

slide-68
SLIDE 68

Microstructures vs mechanical properties of modern multi-phase steels

Tensile strength in MPa 200 400 600 800 1200 1400 1600 10 20 30 40 50 strain in %

perlite retained austenite bainite martensite

TRIP TRIP MS MS 1000 CP CP DP DP F+P

ferrite

68

slide-69
SLIDE 69

Adjustment of multiphase structures of hot-rolled strip

69

slide-70
SLIDE 70

Multiphase steels

70

slide-71
SLIDE 71

Characteristics of Dual Phase (DP) steels

71

slide-72
SLIDE 72

Dual Phase steels: materials concept

72

slide-73
SLIDE 73

Multiphase steels

73

slide-74
SLIDE 74

Characteristics of TRIP steels

74

slide-75
SLIDE 75

TRIP steels: TRansformation Induced Plasticity

75

slide-76
SLIDE 76

TRIP steels: The TRIP-effect

Strain

Stress

76

slide-77
SLIDE 77

Multiphase steels

77

slide-78
SLIDE 78

Characteristics of complex phase steels

78

slide-79
SLIDE 79

Complex phase steels: materials concept

79

slide-80
SLIDE 80

Stress-strain behavior of automotive steels

80

slide-81
SLIDE 81

Outline

  • Automotive evolution
  • Car body structures
  • Automotive steels
  • Mild steels
  • High strength steels
  • Multiphase steels
  • Press hardened steels

81

slide-82
SLIDE 82

Direct - indirect press hardening

82

slide-83
SLIDE 83

Properties of press-hardened steel sheet

83

slide-84
SLIDE 84

Temperature gradient during press hardening

84

slide-85
SLIDE 85

Protection of blank surface

85

slide-86
SLIDE 86

Demands on the surface coating

86

slide-87
SLIDE 87

Changing of surface and microstructure

87

slide-88
SLIDE 88

Trend of hot forming of steel

88

slide-89
SLIDE 89

Hot stamping

89

slide-90
SLIDE 90

Hot stamped of tailored blanks

90

slide-91
SLIDE 91

Innovation Tailored Tempering

91

slide-92
SLIDE 92

Press-hardened B-pillar

92

slide-93
SLIDE 93

Body of Audi A4

93

slide-94
SLIDE 94

Press-hardened parts in VW Passat

94

slide-95
SLIDE 95

Example of a press-hardening plant

95

slide-96
SLIDE 96

Heating of the blank

96

slide-97
SLIDE 97

Blank B-Pillar after heating just before hot stamping

97

slide-98
SLIDE 98

Hot stamping

98

slide-99
SLIDE 99

Application of advanced high strength steels

99

slide-100
SLIDE 100

Trend of advanced high strength steels

Japan World

100

slide-101
SLIDE 101

References

  • Jody N. Hall, Evolution of advanced high strength steels in automotive

applications, General Motors Company, Chair, Joint Policy Council, Auto/Steel Partnership, 2011.

  • Wagner S., Schmid P., Forming of high strength steel sheet, IFU,

Stuttgart, 2012.

  • Smith, W.F. and Hashemi, J., Foundation of metarials science and

engineering, 5th edition, McGraw-Hill, ISBN 978-007-131114-4.

  • Bleck, W., Material Science of Steel, RWTH Aachen University, 2007,

ISBN: 3-86130-923-8.

101

slide-102
SLIDE 102

Thank You

Thank You

102