# Reduced Slit Rolling Power in Rebar Steel Production

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## Abstract

**:**

## 1. Introduction

## 2. Material and Method

^{−1}), and C is the carbon content (wt.%).

^{−1}) at a temperature of 1100 °C.

^{−1}at a temperature range from 900 °C to 1050 °C. In hot rolling with strain rate range up to 100 s

^{−1}, the deformation process can be considered as isothermal, as stated by El-Magd et al. [12], and the temperature effects can be ignored. However, in the current hot rolling processes, the average strain rate reached 200 s

^{−1}, which still could be considered as the moderate strain rate and isothermal conditions that can be applied for simplification. The transition from isothermal to adiabatic deformation depends on the strain (as a source of temperature rise), strain rate, and the material thermal properties, as reported by El-Magd [13]. Therefore, the effect of extreme conditions of both strain and strain rate under the roll knife apex arises. Thus, ductile fracture parameters are going to be measured and compared during the strand severance step.

## 3. Finite Element Modeling

^{−1}and temperature of 1100 °C, as shown in Figure 5. The other material parameters at 1100 °C are taken as follows: Young’s modulus = 95 GPa, Poisson ratio = 0.35, and density = 7800 kg/m

^{3}. The surface-to-surface contact interaction between rollers and billet is modeled through a penalty contact with a tangential friction coefficient of 0.35 [16]. In boundary conditions, the billet longitudinal velocity along the z-axis is set at 150 mm/s, which is equivalent to 47.1 radians/s angular velocity of rollers. All other degrees of freedom are fixed for both rollers and billet. The rollers are modeled as discrete rigid bodies using 4node 3D bilinear rigid quadrilateral (R3D4) elements. While the billet is modeled as a deformable body using an 8-node linear brick hourglass control element with reduced integration (C3D8R). The number of elements in billets A and B are 140,448 and 84,000 with the average aspect ratios of 1.29 and 1.09, respectively. In roller, the number of elements is 2264 with the average aspect ratio of 1.29. The finite element models are shown in Figure 6 and Figure 9. A fully dynamic implicit integration scheme (simulation algorithm) is used; the maximum number of increments are 10,000 and the initial increment size is 0.001, without mass scaling.

## 4. Results and Discussion

#### 4.1. Strip Edging for Preslitting

#### 4.2. Finite Element Simulations of Preslitting Stand

#### 4.3. Deformation Behaviour at the Preslitting Stand

## 5. Conclusions

- The geometry (W/H) of the strip entering the edging pass is numerically tested by compression using grooved and grooveless dies, and verified by comparing it with the images of produced strips.
- The FE result of rolling power (185 kW) is found to be in good agreement with the available experimental data (216 kW). This shows the validation of the FE model and boundary conditions.
- The established FE model is used further to simulate the rolling of a double barreled strip to evaluate its performance in terms of rolling power.
- The FE results revealed that pre slit rolling of single barrel strip is associated with a power reduction of approximately 12.12%.
- Higher localized stresses in a preslitting pass at the roll knife of a single barrel strip could cause severe wear of the roll knife apex.

## Author Contributions

## Funding

## Institutional Review Board Statement

## Informed Consent Statement

## Data Availability Statement

## Acknowledgments

## Conflicts of Interest

## References

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**Figure 1.**Slitting passes of the single barreled strip first and second knifing type passes in the slit rolling subsequence; commonly named ‘dogbone’ pass and ‘slitting’ pass, respectively.

**Figure 3.**Schematic of the roll pass of stand 14. (

**a**) Original grooved rolls, (

**b**) modified grooveless roll, and (

**c**) stand 15 with dogbone pass.

**Figure 4.**Images of real strips as obtained after rolling through stand 14. (

**a**) Strip deformed by grooved rolls, (

**b**) strip deformed by grooveless rolls.

**Figure 5.**Flow curves according to Misaka’s material model as a function of strain and strain rate (20–300 s

^{−1}) at a temperature of 1100 °C.

**Figure 10.**Idealization of the entry strip to stand 14. (

**a**) Strip in the grooved roll, (

**b**) strip in the grooveless roll, and (

**c**) meshed strip for FE simulation.

**Figure 11.**Von Mises stress distribution on the deformed strip after strip deformation by stand 14. (

**a**) Strip deformed by grooved rolls; (

**b**) strip deformed by grooveless rolls.

**Figure 12.**Equivalent plastic strain distribution on the deformed strip after strip deformation by stand 14. (

**a**) Strip deformed by grooved rolls, (

**b**) strip deformed by grooveless rolls.

**Figure 19.**Material deformation parameters for single and double barrels, (

**a**) von Mises stress, (

**b**) equivalent plastic strain, (

**c**) maximum principal logarithmic strain.

**Figure 20.**Schematic representation of the deformation stages at stand 15 (preparation stage for slitting) of the single barreled strip resulting from the edging process at stand 14.

Element | C | Mn | Si | Cr | Ni | S | P | Fe |
---|---|---|---|---|---|---|---|---|

Wt. % | 0.25 | 0.55 | 0.15 | 0.1 | 0.1 | 0.04 | 0.04 | Bal. |

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**MDPI and ACS Style**

Khan, R.; Ataya, S.; Elgammal, I.; Essa, K.
Reduced Slit Rolling Power in Rebar Steel Production. *Materials* **2023**, *16*, 2104.
https://doi.org/10.3390/ma16052104

**AMA Style**

Khan R, Ataya S, Elgammal I, Essa K.
Reduced Slit Rolling Power in Rebar Steel Production. *Materials*. 2023; 16(5):2104.
https://doi.org/10.3390/ma16052104

**Chicago/Turabian Style**

Khan, Rashid, Sabbah Ataya, Islam Elgammal, and Khamis Essa.
2023. "Reduced Slit Rolling Power in Rebar Steel Production" *Materials* 16, no. 5: 2104.
https://doi.org/10.3390/ma16052104