Development of process technology for third generation Advanced High Strength Steel (AHSS)
- Develop third generation AHSS through Quenching and Partitioning (Q&P) route with excellent strength-ductility combinations (T.S. X %El. ≥ 25 GPa % with 800-1200 MPa TS)
- Establish alloy design and kinetics of Q&P process to produce AHSS sheet.
- Establish correlation among process parameters, microstructural evolution and mechanical properties of Q&P processed steel.
RDCIS/SAIL and CSIR-NML has undertaken a collaborative assignment for development of third generation of advanced high strength steel through quenching and partitioning process having high strength with enhanced ductility and good formability.
The scope of the study under this collaborative work would involve following work elements:
- Design of alloy chemistries and heat treatment (quenching & partitioning) parameters
- Heat making and hot rolling at laboratory scale
- Dilatometry test and physical simulation of Q&P cycle in thermo-mechanical process simulator (Gleeble)
- Investigation of the microstructure after quenching & partitioning (Q&P) cycle simulations
- Cold rolling in laboratory scale
- Q&P treatment on cold rolled sheet in prototype annealing simulator
- Evaluation of microstructure and mechanical properties of the cold rolled Q&P samples
- Analyzing results to establish structure – property correlation
- Preparation and submission of completion report
Project is ongoing, Alloy design and kinetics study done followed by heat making and hot rolling to 4.5 mm thickness sheet.
Automobiles are the second largest source of greenhouse gas emissions in the world because of which stringent environmental regulations to control emissions have been incorporated globally in recent years. This calls for weight saving in the body-in-white (BIW) and other automotive parts to maximize the fuel efficiency.
Quenching and partitioning advanced high strength steel will enable end user to use thinner gauge, which would reduce overall weight of the vehicle leading to lower fuel consumption and greenhouse gas emissions.
Fig1: Thermodynamic property diagram showing the variation of phase fraction with temperature in Alloy 1 and Alloy 2
Fig2: Kinetics study showing variation of final retained austenite fraction with quenching temperature in quenching and partitioning process of alloy 1 and alloy 2.
Fig.3: SEM image showing mostly martensitic structure in hot rolled sheet(~20 mm) of alloy 1 and alloy 2.