High strength formable carbon-manganese steel sheets for automotive applications

Directorate-General For Research And Innovation European Commission

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Industrial research and development

Sujets

• Sciences et techniques

Informations

• Publié par: DIRECTORATE-GENERAL-FOR-RESEARCH-AND-INNOVATION-EUROPEAN-COMMISSION
• Nombre de lectures: 8
• Langue: English
• Poids de l'ouvrage: 6 Mo

Extrait

ISSN 1018-5593
European Commission
technical steel research
Properties and in-service performance
High strength formable
carbon-manganese steel sheets
for automotive applications
STEEL RESEARCH European Commission
technical steel research
Properties and in-service performance
High strength formable
carbon-manganese steel sheets
for automotive applications
A. Jones, J. H. Reynolds, P. J. Evans, B. A. Wade
British Steel pic
9 Albert Embankment
London SE1 7SN
United Kingdom
Contract No 7210-MB/802
1 September 1990 to 31 August 1993
Final report
Directorate-General
Science, Research and Development
1998 EUR 17864 EN LEGAL NOTICE
Neither the European Commission nor any person acting on behalf of the Commission
is responsible for the use which might be made of the following information.
A great deal of additional information on the European Union is available on the Internet.
It can be accessed through the Europa server (http://europa.eu.int).
Cataloguing data can be found at the end of this publication.
Luxembourg: Office for Official Publications of the European Communities, 1998
ISBN 92-828-2150-1
© European Communities, 1998
Reproduction is authorised provided the source is acknowledged.
Printed in Luxembourg
PRINTED ON WHITE CHLORINE-FREE PAPER CONTENTS
Page
1. INTRODUCTION 13
2. WORK CARRIED OUT AT WELSH LABORATORIES 14
2.1 Laboratory Made TRIP Steels 1
2.1.1 Experimental Procedure
2.1.1.1y Made Melts2 Testing Using a Cooling Simulator4
2.1.1.3 Measurements of Retained Austenite by X-Ray Diffraction 1
2.1.2 Results and Discussion5
2.1.2.1 Retained Austenite2 Tensile Properties 16
2.1.2.3 Work Hardening Behaviour7 4 Strain Induced Transformation of Austenite 1
2.2 Structure Property Relationships of C-Mn Steels
Produced on a Wide Hot Strip Mill8
2.2.1 Experimental Procedure
2.2.2 Results and Discussion
2.2.2.1 Structure-Tensile Strength Relationship 12 Structure-Elongation Relationship9
2.3 Studies of Transformation Behaviour of TRIP Type
Steels. 1
2.3.1 Experimental Procedure & 1
2.3.1.1 Tests Using a Hot Deformation Dilatometer
2.3.2 Results and Discussion
2.3.2.1 Three-Stage Cooling (Paths AtB,C) 20 2 Continuousg (Path D)
2.4 Evaluation of the Microstructures and Properties of a TRIP
Type Production Steel 2
2.4.1 Experimental Details
2.4.1.1 Productions0 2 Tensile and Hole Expansion Tests1
2.4.1.3 Microstructural Evaluation4 Low Cycle Fatigue Tests
2.4.1.5 Forming Limit Diagram (FLD) 22
2.4.2 Results 2
2.4.2.1 Tensile Properties
2.4.2.2. Microstructures and Quantitative Measurements of
Retained Austenite
2.4.2.3 Hole Expansion Performance4 Low Cycle Fatigue Tests3
2.4.2.5 Forming Limit Diagram (FLD) 2
2.4.3 Discussion
2.5 Evaluation of the Microstructures and Properties of a
Carbon-Manganese-Silicon Production Steel 24
2.5.1 Experimental Details
2.5.1.1 Tensile Tests 22.5.1.2 Metallographic Examination 7¿ 3 Measurements of Retained Austenite by X-Ray Diffraction 25
2.5.2 Results
25
2.5.2.1 Tensile Properties
25 2 Microstructures
25
2.5.3 Discussion
25
WORK CARRIED OUT AT SWINDEN LABORATORIES 25
3.1. Experimental Procedure
2
3.1.1 Laboratory Made Casts
2
3.1.1.1 CMn Steels
25 2 TRIPs
26
3.1.1.3 Dual-Phase Steels (DP)
26
3.1.2 Production Material
26
3.1.2.1 CMn Steels
26 2e Steels
27
3.1.3 Determination of Continuous Cooling Transformation
Diagrams for Experimental Casts 27
3.1.4 Multistage Treatments of Experimental Casts >
3.1.4.1 Dilatometers
2
3.1.4.2 Simulative Heat Treatments
28
3.1.5 Determination of Continuous Cooling Transformation
Diagrams for Production Casts9
3.2 Results 2
3.2.1 Continuous Cooling Transformation 2
3.2.1.1 Undeformed Transformation Diagrams
3.2.1.1.1 Base CMn, Dual-Phase and TRIP Steels2 CMn Steel Types
3.2.1.1.3. Dual-Phase Steel Types 30
3.2.1.1.3.1 Low Si Types2 SiCr Types
3.2.1.1.3.3 SiMos
3.2.1.1.4 TRIP Steel Type
3.2.1.2 Transformation Behaviour Following Deformation 3
3.2.1.2.1 CMn Steel TypesO 2 Dual-Phase Steel Types1
3.2.1.2.2.1 Low Si Types 3I 2 SiCr Types
3.2.1.2.2.3 SiMos
3.2.1.2.3 TRIP Steel Types
3.2.2. Multistage Thermomechanical Treatments 3
3.2.3e Heat Treatments *2
3.2.4 Dual-Phase Production Trial Casts3
3.3 Discussion of Work Carried out at S winden Laboratories 3
3.3.1 Effects of Composition on Transformation Behaviour 3
3.3.2s of Deformation onnr5
3.3.3 Production Trials 37
4. GENERAL DISCUSSION9
4.1 Optimisation of Composition and Structures 3
4.1.1 CMn Steel
4.1.2 Dual-Phase Steels 40 4.1.3 Tri-Phase C-Mn-Si Steel 40
4.1.4 TRIP Steels
4.2 Control of Processing Variables1
4.2.1 Dual-Phase Steels
4.2.2 TRIP Steels2
4.3 Factors Affecting Structure/Properties 4
4.3.1 Carbon-Manganese and Dual-Phase Steels 4
4.3.2 TRIP Steels 43
4.4 Possible Rationalisation of Compositions4
4.5 Future Work
5. CONCLUSIONS5
REFERENCES6
TABLES
FIGURES 89 LIST OF TABLES
1. CHEMICAL COMPOSITIONS OF STEELS.
2. COOLING CONDITIONS AND RESULTS OF EVALUATION.
3. MEASUREMENTS OF RETAINED AUSTENITE.
4. TENSILE PROPERTIES OF STEELS COOLED USING VARIOUS CONDITIONS
(SEE TABLE 2).
5. CHANGE IN VOLUME FRACTION OF RETAINED AUSTENITE DURING TENSILE
STRAINING.
6. TENSILE PROPERTIES AND MICROSTRUCTURES OF CARBON-MANGANESE
STEELS PRODUCED ON A WIDE HOT STRIP MILL.
7. MICROSTRUCTURES PRESENT IN DILATOMETER SAMPLES.
8. RESULTS OF CONTINUOUS COOLING DILATOMETRIC TESTS AFTER
DEFORMATION.
9. TENSILE PROPERTIES FOR STEEL 14 (COIL C).
10.ES FOR STEEL 14 (COIL D).
11. RETAINED AUSTENITE MEASUREMENTS FOR STEEL 14 - BEFORE STRAINING.
12.DES FOR STEEL 14 - AFTER SPECIMEN
STRAINING.
13. HOLE EXPANSION VALUES FOR STEEL 14.
14. CYCLIC STRESS AND TOTAL STRAIN AMPLITUDE DURING LOW CYCLE
FATIGUE TESTS USING CONSTANT PLASTIC STRAIN AMPLITUDE FOR A TRIP
TYPE PRODUCTION STEEL.
15. RESULTS OF LOW CYCLE FATIGUE TESTS USING CONSTANT PLASTIC
AMPLITUDE FOR A TRIP TYPE PRODUCTION STEEL.
16. TENSILE PROPERTIES AND RETAINED AUSTENITE CONTENTS OF SELECTED
SPECIMENS.
17. RELATIONSHIP BETWEEN HOLE EXPANSION AND AMOUNT OF RETAINED
AUSTENITE.
18. TENSILE PROPERTIES OF STEEL 13.
19. MICROSTRUCTURES PRESENT IN STEEL 13.
20. CHEMICAL COMPOSITION OF LABORATORY AND PRODUCTION MATERIALS.
21. ACTUAL AND CALCULATED Aci AND Ac3 TEMPERATURES.
22. MICROSTRUCTURE AND HARDNESS DETERMINATIONS, FROM
UNDEFORMED SAMPLES FOR STEEL IS. 23. MICROSTRUCTURE AND HARDNESS DETERMINATIONS FROM 30%
DEFORMED SAMPLES FOR STEEL IS.
24.E AND HARDNESSS FROM
UNDEFORMED SAMPLES FOR STEEL 3S.
25.E AND HARDNESS DETERMINATIONS FROM 30%
DEFORMED SAMPLES FOR STEEL 3S.
26. MICROSTRUCTURE AND HARDNESSS FROM
UNDEFORMED SAMPLES FOR STEEL 4S.
27.E AND HARDNESS DETERMINATIONS FROM 30%
DEFORMED SAMPLES FOR STEEL 4S.
28.E AND HARDNESSS FROM
UNDEFORMED SAMPLES FOR STEEL 5S.
29. MICROSTRUCTURE AND HARDNESS DETERMINATIONS FROM 30%
DEFORMED SAMPLES FOR STEEL 5S.
30.E AND HARDNESSS FROM
UNDEFORMED SAMPLES FOR STEEL 6S.
31.E AND HARDNESS DETERMINATIONS FROM 30^
DEFORMED SAMPLES FOR STEEL 6S.
32. MICROSTRUCTURE AND HARDNESS'S FROM
UNDEFORMED SAMPLES FOR STEEL 7S.
33.E AND HARDNESS DETERMINATIONS FROM 30<v
DEFORMED SAMPLES FOR STEEL 7S.
34.E AND HARDNESSS FROM
UNDEFORMED SAMPLES FOR STEEL 8S.
35. MICROSTRUCTURE AND HARDNESS DETERMINATIONS FROM 30'>
DEFORMED SAMPLES FOR STEEL 8S.
36.E AND HARDNESSS FROM
UNDEFORMED SAMPLES FOR STEEL 9S.
37.E AND HARDNESS DETERMINATIONS FROM 30?,
DEFORMED SAMPLES FOR STEEL 9S.
38. MICROSTRUCTURE AND HARDNESSS FROM
UNDEFORMED SAMPLES FOR STEEL 10S.
39.E AND HARDNESS DETERMINATIONS FROM 30%
DEFORMED SAMPLES FOR STEEL 10S.
40.E AND HARDNESSS FROM
UNDEFORMED SAMPLES FOR STEEL US.
41. MICROSTRUCTURE AND HARDNESS DETERMINATIONS FROM 30%
DEFORMED SAMPLES FOR STEEL US. 42. MICROSTRUCTURE AND HARDNESS DETERMINATIONS FROM
UNDEFORMED SAMPLES FOR STEEL 12S.
43.E AND HARDNESSS FROM 30%
DEFORMED SAMPLES FOR STEEL 12S.
44.E AND HARDNESS DETERMINATIONS FROM
UNDEFORMED SAMPLES FOR STEEL 13S.
45. MICROSTRUCTURE AND HARDNESSS FROM 30%
DEFORMED SAMPLES FOR STEEL 13S.
46.E AND HARDNESS DETERMINATIONS FROM
UNDEFORMED SAMPLES FOR STEEL 14S.
47.E AND HARDNESSS FROM 30%
DEFORMED SAMPLES FOR STEEL 14S.
48. MICROSTRUCTURE AND HARDNESS DETERMINATIONS FROM
UNDEFORMED SAMPLES FOR STEEL 16S.
49.E AND HARDNESSS FROM 30%
DEFORMED SAMPLES FOR STEEL 16S.
50.E AND HARDNESS DETERMINATIONS FROM
UNDEFORMED SAMPLES FOR STEEL 17S.
51. MICROSTRUCTURE AND HARDNESSS FROM 30%
DEFORMED SAMPLES FOR STEEL 17S.
52.E AND HARDNESS DETERMINATIONS FROM
UNDEFORMED SAMPLES FOR STEEL 18S.
53.E AND HARDNESSS FROM 30%
DEFORMED SAMPLES FOR STEEL 18S.
54. PERCENTAGE OF RETAINED AUSTENITE AND HARDNESS OF SAMPLES
FOLLOWING MULTISTAGE TREATMENTS.
55. TENSILE PROPERTIES OF STEEL 6S (TRIP) FOLLOWING MULTISTAGE
HEAT TREATMENTS.
56.E