Grant: Collaborative Research and Development Grants
University of Waterloo
$84,616.00
Understanding and Controlling Transformations in the HAZ of 3G AHSS
EF 2020-21
Résumé
The Intergovernmental Panel on Climate Change reported that greenhouse gas (GHG) emissions must decrease to net-zero by 2055 to limit global warming to 1.5°C above pre-industrial levels. Automakers plan to decrease the GHG emissions of their vehicles by using ultra high strength steels (UHSS), with ultimate tensile strength (UTS) greater than 1 GPa, in their vehicles. UHSS allows thinner steels to be used for parts, reducing part weight, while retaining part strength. However, when UHSS are resistance spot welded (RSW), their complex composition and microstructure can lead to hardness peaks, softening, and liquid metal embrittlement (LME) cracks near the weld. These phenomena are not fully understood, but, it is known that thermal history will affect both weld hardness and LME.
The proposed CRD project will better understand transformations and LME formation occurring during RSW of UHSS. This knowledge will be used to modify the RSW process to maximize joint performance and minimize LME cracking. To facilitate this, the weldability steels with UTS of 980 MPa and 1180 MPa. In-use steels with dual-phase (DP) microstructure and state-of-the-art Quench & Partition (QP) steels will be compared, enabling an understanding of how base material strength and microstructure affect transformations during welding and LME. The project will characterize transformations in the heat affected zone (HAZ) through changes in observed structures and mechanical properties. LME sensitivity in these steels will also be characterized. LME sensitivity will be mapped as with respect to welding parameters and in-situ observations of crack formation will be made. Understanding how thermal history affects HAZ transformations and LME will be used to optimize the welding process to maximize post-weld quality, informing a model to predict post-weld properties and cracking severity. These results will benefit Canada by increasing adoption of new UHSS steels into vehicles, creating a demand for Canadian steelmakers to make these high value steels, that will be used in Canadian automotive production.
Programme
Collaborative Research and Development Grants
Bénéficiaire
Emplacement
Ontario, Canada
Type de bénéficiaire
Academia
Type
Grant
Source
NSERC's Awards Data
Tel que publié
Application id
539602-2019
Name nom
Biro, Elliot
Department département
Mechanical Engineering and Mechatronics
Organization id
33
Institution établissement
University of Waterloo
Province en
Ontario
Province fr
Ontario
Country en
CANADA
Country fr
CANADA
Fiscal year exercice financier
2020
Competition year année de concours
2019
Award amount
84616
Program id
CRDPJ
Program name en
Collaborative Research and Development Grants
Program name fr
Subventions de recherche et développement coopérative
Group en
Research partnerships programs
Group fr
Programmes de partenariat
Committee code
96
Committee name en
RPP Internal Decision Cttee
Committee name fr
Cté de décision interne - PPR
Area of application code
1208
Area of application group en
Advancement of knowledge
Area of application group fr
Avancement des connaissances
Area of application en
Materials sciences
Area of application fr
Sciences des matériaux
Research subject code
2001
Research subject group en
Materials science and technology
Research subject group fr
Science et technologie des matériaux
Research subject en
Materials structure, properties and testing
Research subject fr
Structure, propriétés et essais des matériaux
Installment
inst:2 - 2
Partie
1
Nb partie
2
Application title
Understanding and Controlling Transformations in the HAZ of 3G AHSS
Keyword
NSERC
Application summary
The Intergovernmental Panel on Climate Change reported that greenhouse gas (GHG) emissions must decrease to net-zero by 2055 to limit global warming to 1.5°C above pre-industrial levels. Automakers plan to decrease the GHG emissions of their vehicles by using ultra high strength steels (UHSS), with ultimate tensile strength (UTS) greater than 1 GPa, in their vehicles. UHSS allows thinner steels to be used for parts, reducing part weight, while retaining part strength. However, when UHSS are resistance spot welded (RSW), their complex composition and microstructure can lead to hardness peaks, softening, and liquid metal embrittlement (LME) cracks near the weld. These phenomena are not fully understood, but, it is known that thermal history will affect both weld hardness and LME.
The proposed CRD project will better understand transformations and LME formation occurring during RSW of UHSS. This knowledge will be used to modify the RSW process to maximize joint performance and minimize LME cracking. To facilitate this, the weldability steels with UTS of 980 MPa and 1180 MPa. In-use steels with dual-phase (DP) microstructure and state-of-the-art Quench & Partition (QP) steels will be compared, enabling an understanding of how base material strength and microstructure affect transformations during welding and LME. The project will characterize transformations in the heat affected zone (HAZ) through changes in observed structures and mechanical properties. LME sensitivity in these steels will also be characterized. LME sensitivity will be mapped as with respect to welding parameters and in-situ observations of crack formation will be made. Understanding how thermal history affects HAZ transformations and LME will be used to optimize the welding process to maximize post-weld quality, informing a model to predict post-weld properties and cracking severity. These results will benefit Canada by increasing adoption of new UHSS steels into vehicles, creating a demand for Canadian steelmakers to make these high value steels, that will be used in Canadian automotive production.
