Strain hardening characteristics of deep drawing quality steels with geometric constraints
Bibliographic record
Abstract
Strain hardening characteristics of two rolled deep drawing quality (DDQ) steels, namely, interstitial free (IF) and aluminium killed (AK), have been studied with and without the presence of geometric constraints at room temperature. Strain hardening exponent and rate are investigated for plain, centre holed and double notched sheet specimens for both longitudinal and transversal orientations. Four empirical relations based on total and incremental stress and strain components are considered to get a deeper insight into the deformation and workhardening behaviour of annealed sheets. Strain hardening exponents and yield strengths for steel with ultralow carbon contents (IF) are found in the range of 0·22–0·30 and 145–170 MPa respectively. The steel grade (AK) with higher carbon content (0·028%) and yield strength (174–197 MPa) exhibits strain hardening exponent around 0·18–0·27. Single and two-stage workhardening is observed for the IF and AK grades. Workhardening as a function of plastic strain follows the power law relation of the form workhardening rate (WHR) = α(ϵT)β . A transition from high to low hardening rate tends to occur for strains ranging from 0·05 to 0·10. An analytical model is formulated for theoretical estimation of strain hardening exponent from true strain data. The experimentally determined and the theoretically computed strain hardening exponent data match fairly well.On a étudié les caractéristiques d’écrouissage de deux aciers laminés de qualité emboutissage (DDQ), nommément sans interstitiel (IF) et calmé à l’aluminium (AK), avec et sans la présence de contraintes géométriques, à la température de la pièce. On examine l’exposant et la vitesse d’écrouissage pour des échantillons de tôle lisse, à trou central et avec entaille double, tant dans l’orientation longitudinale que transverse. On considère quatre relations empiriques basées sur les composantes de contrainte et de déformation, totales et incrémentales, afin d’obtenir une compréhension plus profonde du comportement de déformation et de durcissement des tôles recuites. La valeur des exposants d’écrouissage et les limites d’élasticité pour l’acier à teneur extrêmement basse en carbone (IF) se trouvent dans la gamme de 0·22–0·30 et 145–170 MPa, respectivement. La nuance d’acier (AK) avec une teneur plus élevée en carbone (0·028%) et une limite d’élasticité plus élevée (174–197 MPa) exhibe un exposant d’écrouissage autour de 0·18–0·27. On observe le durcissement simple ou en deux étapes pour les nuances sans interstitiel ou calmé à l’aluminium. Le durcissement en fonction de la déformation plastique suit une relation de loi de puissance de la forme WHR = α(ϵT)β. Une transition d’une vitesse élevée à basse du durcissement tend à se produire pour les déformations allant de 0·05–0·10. On formule un modèle analytique pour l’estimation théorique de l’exposant d’écrouissage à partir de véritables données de déformation. Les données d’exposant d’écrouissage déterminées expérimentalement et calculées théoriquement se rapprochent relativement bien.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".