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

Mechanical properties of different phases in steels Phase Phase R e , MPa R e , MPa R m , MPa R m , MPa A, % A, % Hardening, HV Hardening, HV  280  280  50  50 Interstitial free condition Interstitial free condition 100-150 100-150 - - (Ferrite) (Ferrite)  220  220  300  300  45  45 Ferrite (unalloyed) Ferrite (unalloyed) - -  330  330  550  550  35  35 Ferrite (0,7% Ni, 0,6% Cr) Ferrite (0,7% Ni, 0,6% Cr) about 180 about 180  300  300  500  500  18  18 Ferrite (13% Cr) Ferrite (13% Cr) - -  900  900  1000  1000  10  10 Pearlite Pearlite - -  3000  3000 Cementite Cementite - - - - - - Bainite (  0,1% C) Bainite (  0,1% C)  25  25 400-800 400-800 550-1200 550-1200 about 320 about 320 Martensite (  0,1% C) Martensite (  0,1% C)  800  800  1200  1200  5  5 about 380 about 380 Martensite (  0,4% C) Martensite (  0,4% C)  2400  2400 - - - - - -  300  300  600  600  40  40 Austenite (18% Cr, 8% Ni) Austenite (18% Cr, 8% Ni) - - 64

Homogeneity of grain structure - properties 65

Characteristics of AHSS 66

Microstructures of modern multiphase steels Higher strength 67

Microstructures vs mechanical properties of modern multi-phase steels 50 40 F+P 30 DP DP strain in % TRIP TRIP 20 CP CP 10 MS MS 0 200 400 600 800 1200 1400 1600 1000 Tensile strength in MPa ferrite perlite retained austenite bainite martensite 68

Adjustment of multiphase structures of hot-rolled strip 69

Multiphase steels 70

Characteristics of Dual Phase (DP) steels 71

Dual Phase steels: materials concept 72

Multiphase steels 73

Characteristics of TRIP steels 74

TRIP steels: TRansformation Induced Plasticity 75

TRIP steels: The TRIP-effect Stress Strain 76

Multiphase steels 77

Characteristics of complex phase steels 78

Complex phase steels: materials concept 79

Stress-strain behavior of automotive steels 80

Outline • Automotive evolution • Car body structures • Automotive steels • Mild steels • High strength steels • Multiphase steels • Press hardened steels 81

Direct - indirect press hardening 82

Properties of press-hardened steel sheet 83

Temperature gradient during press hardening 84

Protection of blank surface 85

Demands on the surface coating 86

Changing of surface and microstructure 87

Trend of hot forming of steel 88

Hot stamping 89

Hot stamped of tailored blanks 90

Innovation Tailored Tempering 91

Press-hardened B-pillar 92

Body of Audi A4 93

Press-hardened parts in VW Passat 94

Example of a press-hardening plant 95

Heating of the blank 96

Blank B-Pillar after heating just before hot stamping 97

Hot stamping 98

Application of advanced high strength steels 99

Trend of advanced high strength steels World Japan 100