Material Behavior Characterization via Multi-Directional Deformation of Sheet Metal: Session I
Sponsored by: TMS Materials Processing and Manufacturing Division, TMS: Shaping and Forming Committee
Program Organizers: Daniel Coughlin, United States Steel Corp; Cody Miller, Los Alamos National Laboratory; Kester Clarke, Los Alamos National Laboratory; Piyush Upadhyay, Pacific Northwest National Laboratory; John Carsley, Novelis, Inc.
Monday 8:30 AM
March 20, 2023
Room: Aqua 309
Location: Hilton
Session Chair: Daniel Coughlin, United States Steel Corporation; Cody Miller, Los Alamos National Laboratory
8:30 AM Cancelled
Comparison of Plasticity and Fracture Behaviors of Conventional and 3rd Gen. AHSS: Sriram Sadagopan1; Hong Zhu1; Gang Huang1; Brian Lin1; 1ArcelorMittal Global R&D
The recent development of 3rd generation of Advanced High Strength Steels offers an attractive solution to automotive OEMs for affordable lightweighting while at the same time offering good formability and safety performance. While the development has mostly focused on conventional measures of improved formability such as uniform elongation, bendability to name a few, very little work has been published on comparing the behaviors of the 3rd Gen. AHSS to conventional AHSS such as DP steels at the same strength level. This paper provides an in-depth comparison of the behavior of 3rd Gen. AHSS to conventional AHSS under simulative stamping conditions with an emphasis on plasticity and fracture behavior under different stress states. Furthermore, the paper will also present results on evolution of the microstructure of these steels with increasing deformation and the implication of these results on the eventual fracture behavior.
9:00 AM Invited
A Practical Edge Fracture Limit for the Advanced High Strength Steels: Hua-Chu Shih1; 1United States Steel
A robust methodology is in demand to evaluate and develop edge fracture limit and subsequently predict the sheared edge formability. In the study, different shear edge conditions of various AHSS materials were evaluated by the conventional hole expansion test and the half specimen dome test (HSDT). The edge fracture limit developed from HSDT method was validated by FEA predictions with experimental data. Results indicated that material processed along rolling direction under the 15-18% cutting clearance can deliver a competitive sheared edge formability as the laser cutting edge. The edge limit developed from the hole expansion test can be utilized for a more conservative sheared edge formability prediction on normal mechanical-trim edge blank, while HSDT data for a properly prepared edge condition can be used for the prediction of laser-trim edge blank. A proposed five levels shear face condition vs. stretchability reduction chart is recommended for a quick field validation criterion.
9:30 AM Invited
Characterization and Modeling of Anisotropic Fracture of Advanced High Strength Steels: Jun Hu1; 1Cleveland-Cliffs Steel
New generations of advanced high strength steels (AHSSs) possess improved strain hardening behavior and resistance to necking that are favorable for automotive body applications. Yet the multiphase microstructure that brings this merit also causes complex orientation-dependent fracture behavior in these steels. This work started from conducting a series of experiments to exhibit the anisotropic fracture of selected AHSSs and highlight the importance and necessity of anisotropic fracture models. A stress-based and a strain-based anisotropic fracture models were calibrated based on the same coupon-level experimental results. Subsequently, with the same plasticity model, the two fracture models were implemented into finite element simulations of a sub-assembly level experiment of sophisticated loading conditions. Eventually, the fracture simulations based on the two models were evaluated by the experimental measurements and compared with each other to reveal their highlights, limitations, and potential improvements.
10:00 AM Break
10:20 AM
Examining Temperature, Strain Rate, and Strain State on TRIP-assisted Steel Forming Behavior: Christopher Finfrock1; Nathan Smith2; Melissa Thrun1; Amy Clarke1; Kester Clarke1; 1Colorado School of Mines; 2Colorado School of Mines/Montana Tech
TRansformation Induced Plasticity (TRIP) assisted alloys take advantage of metastable phase changes during deformation to increase strain hardening rate and delay strain localization. The stability of the metastable phases is important and may be affected by deformation parameters such as temperature, strain rate, and strain path. However, decoupling the effects of these parameters can be difficult especially when considering high strength metals that may generate significant heat from work during deformation. Here, we present outcomes of experiments to separate the effects of strain rates, temperatures, and strain states relevant to forming of high strength alloys at or near room temperature.