Evolution of Roughness on Straining of Interstitial Free – IF Steel Sheet

2012 ◽  
Vol 504-506 ◽  
pp. 83-88 ◽  
Author(s):  
Ricardo Kirchhof Unfer ◽  
José Divo Bressan
Keyword(s):  
Plastic Strain ◽  
Tensile Test ◽  
Steel Sheet ◽  
Material Behavior ◽  
Uniaxial Tensile ◽  
Interstitial Free ◽  
If Steel ◽  
Local Necking ◽  
Incremental Step ◽  
If Steel Sheet

This study aims to assess the evolution of surface roughness and waviness parameters with plastic strain in Interstitial Free – IF steel sheet. For the achievement of this study, it was considered various roughness and waviness profile parameters such as: arithmetic average roughness (Ra), maximum distance peak-valley (Rt), average waviness (Wa) and waviness of the total height peak-valley (Wt). Tensile test specimens of IF steel at 0º, 45º and 90º to the direction of rolling were fabricated. After preparing the sheet proof specimens, it was performed simple tensile tests and measurements of roughness and waviness of the specimen surface at various strain stages resulting in a large quantity of data. During the tensile test, it has been measured the following plastic strain to indicate the incremental step: (e1) longitudinal strain and (e2) transverse strain. From these data, it was possible to obtain points needed to plot the curves of roughness and waviness parameters versus strain and to determine the material behavior using equations of the equivalent strain. From the curves drawn it was possible to see how the material roughness and waviness behaves during the straining in the uniaxial tensile state, with the possibility to predict the influence of plastic strain on roughness and waviness parameters and the onset of local necking of IF steel sheet. The waviness parameters Wt is the best for characterizing the onset of local necking.

Experimental Waviness Evolution of Interstitial Free - IF Steel Sheet under Biaxial Stretching

2015 ◽  
Vol 651-653 ◽  
pp. 102-107 ◽  
Author(s):  
José Divo Bressan ◽  
Ricardo Kirchoff Unfer
Keyword(s):  
Plastic Strain ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
Steel Sheet ◽  
Interstitial Free ◽  
If Steel ◽  
Local Necking ◽  
Biaxial Stretching ◽  
Biaxial Tests ◽  
If Steel Sheet

The purpose of present study is to present experimental results and a mathematical model for the evolution of surface waviness parameters with plastic strain of Interstitial Free - IF steel sheet under uniaxial and biaxial stretching tests. Roughness and waviness are very important quality parameters to be evaluated in sheet metal forming. Various waviness profile parameters such as the arithmetic average waviness Wa, the total height peak-valley waviness Wt, maximum peak height Pp and maximum valley depth Pv were measured during uniaxial and biaxial tests. Tensile test specimens at 0º, 45º and 90º to the direction of rolling and Nakazima type specimens of IF steel were fabricated. After preparing the test specimens, incremental simple tensile and Nakazima biaxial tests with flat punch were performed to characterize the negative and positive quadrant of the Map of Principal Surface Limit Strains, MPLS, of IF steel sheet. Measurements of waviness parameters of the specimen surface at incremental plastic strain stages were performed at the same surface site. Also, during the uniaxial and biaxial tests, the following plastic strains were calculated from printed circular mesh at each incremental step: ε1longitudinal major strain and ε2transverse minor strain. From these data, curves of waviness parameters versus equivalent strain were plotted to obtain a phenomenological equation of 4th or 3rd degree polynomial type. Furthermore, the growth rates of Wa and Wt parameters with the equivalent plastic strain were assessed. From the growth rate curves, it was possible to verify how the sheet thickness imperfections evolves during straining, being possible to predict the influence of plastic strain on the waviness values of IF steel sheets. From the analysis of Wa and Wt growth rates during straining, it was possible to proposed a criteria for the onset of local necking or limit strains in the MPLS. The waviness parameters Wt is the best for characterizing the onset of local necking in sheet metal forming.

Forming limit strains of interstitial free-IF steel sheet

2016 ◽  
Author(s):  
José Divo Bressan ◽  
Luciano Pessanha Moreira ◽  
Maria Carolina dos Santos Freitas
Keyword(s):  
Steel Sheet ◽  
Forming Limit ◽  
Interstitial Free ◽  
If Steel ◽  
If Steel Sheet

Microstructure and Texture Evolution in Cold Rolled Interstitial Free (IF) Steel Sheet during Annealing under AC Magnetic Field

2010 ◽  
Vol 638-642 ◽  
pp. 2781-2786
Author(s):  
Chang Shu He ◽  
Sadahiro Tsurekawa ◽  
Hiroyuki Kokawa ◽  
Xiang Zhao ◽  
Liang Zuo
Keyword(s):  
Magnetic Field ◽  
Steel Sheet ◽  
Texture Evolution ◽  
Rolling Direction ◽  
Recrystallization Annealing ◽  
Interstitial Free ◽  
If Steel ◽  
Ac Magnetic Field ◽  
Cold Rolled ◽  
If Steel Sheet

An AC magnetic field (0.5Tesla) is applied with the field direction perpendicular to the rolling direction during annealing of a 76% cold-rolled IF steel sheet. Microstructure and texture evolution in the as-annealed specimens were determined using SEM based OIM technique. It is found that the recrystallization is noticeably retarded by AC magnetic field annealing. At the early stage of recrystallization (annealing at 650°C for 30min), the development of (111) <123> orientations was favored by the AC magnetic field. With progress of recrystallization (annealing at 700°C and 750°C for 30min), the applied AC magnetic field suppressed the development of γ-fiber recrystallization textures to some extent.

Characteristics of Recrystallization Texture Evolution in High Magnetic Field for Interstitial Free (IF) Steel Sheet

2005 ◽  
Vol 495-497 ◽  
pp. 465-470 ◽  
Author(s):  
Chang Shu He ◽  
Yu Dong Zhang ◽  
X. Zhao ◽  
Liang Zuo ◽  
Claude Esling
Keyword(s):  
Magnetic Field ◽  
High Magnetic Field ◽  
Recrystallization Texture ◽  
Steel Sheet ◽  
Texture Evolution ◽  
Interstitial Free ◽  
If Steel ◽  
Direction Parallel ◽  
The Magnetic Field ◽  
If Steel Sheet

High magnetic field is applied with the field direction parallel to the rolling direction during annealing of a cold rolled IF steel sheet. Results of X-ray ODF analysis show that, magnetic field annealing retards the normal recrystallization texture evolution for the IF steel sheet. It is worth noting that an abnormal increase of orientation intensity at {100}<110> is found after magnetic annealing for 25min at 650°C. When the magnetic field strength is increased from 10 Tesla to 14 Tesla, the a-fiber is further strengthened, especially the {100}<110> component. Combined with EBSD analysis results, it is considered that the magnetic field does not change the mechanism of recrystallization texture evolution for the IF steel sheet in the present case.

Effects of Electric Field Annealing on Recrystallization Texture and Plastic Strain Ratio (r-Value) of IF Steel Sheet

2007 ◽  
Vol 539-543 ◽  
pp. 3478-3483
Author(s):  
Xiang Zhao ◽  
Chang Shu He ◽  
J. Xu ◽  
Liang Zuo
Keyword(s):  
Plastic Strain ◽  
Electric Field ◽  
Steel Sheet ◽  
Strain Ratio ◽  
Fiber Texture ◽  
If Steel ◽  
Plastic Strain Ratio ◽  
Field Annealing ◽  
R Value ◽  
If Steel Sheet

Effects of electric field annealing on recrystallization texture and average plastic strain ratio (r value) of IF steel sheet were studied by mean of X ray diffraction ODF analysis and the tensile test. Specimens of 75% cold-rolled IF steel sheet were annealed at 850flC for 25min,with and without electric field annealing respectively. Results show that the electric field annealing does not change the type of recrystallization texture and its formation mechanism in IF deep-drawing steel sheet, but improves the formation and development of recrystallization i-fiber texture, enhances the intensity of i-fiber texture, and retards the formation and development of c-fiber texture. Comparing with the conventional annealing, electric field annealing improves the average plastic strain ratio (r value). Possible reasons for the intensification of recrystallization i-fiber texture with the electric field applied may attribute to the reduction of stored energy, thus hindering the formation of other orientated nuclei and enhancing the nucleating ratio of i-oriented nuclei. And the intensification of recrystallization i-fiber texture was considered as the main reason for the enhancement of the plastic strain ratio (r value) in IF steel sheet.

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