# Acquiring High-Quality Oil Casing Steel 26CrMoVTiB under Optimal Continuous Casting Process Conditions

^{1}

^{2}

^{3}

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## Abstract

**:**

## 1. Introduction

## 2. Methods

#### 2.1. Mathematical Model

_{p}is the thermal capacity, T is the temperature, λ is the thermal conductivity, ΔH is the solidification latent heat, and f

_{s}is the solidification rate.

_{N}denotes the average nucleation supercooling degree, ΔT

_{σ}is the standard deviation of the nucleation supercooling degree, and n

_{max}is the compliance of maximum nucleation density with normal distribution.

_{1}(ΔT)

^{2}+ a

_{2}(ΔT)

^{3}

_{1}= 0 and a

_{2}= 7.511 × 10

^{−6}m·s

^{−1}·K

^{−3}.

#### 2.2. Thermo-Physical Properties

#### 2.3. Model Verification

#### 2.4. Industrial Trial Production

## 3. Results and Discussion

#### 3.1. Influence of the Superheat Degree on the Solidification Structure

#### 3.2. Influence of the Casting Speed on the Solidification Structure

#### 3.3. Influence of the Secondary Cooling Intensity on the Solidification Structure

#### 3.4. Industrial Trial Production Results

## 4. Conclusions

## Author Contributions

## Funding

## Conflicts of Interest

## References

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**Figure 2.**Changes in (

**a**) density, (

**b**) thermal conductivity, (

**c**) solid fraction, and (

**d**) enthalpy of the 26CrMoVTiB steel with temperature.

**Figure 4.**Simulation results and measured results of a continuous casting round billet, where the casting billet diameter is 178 mm on the left side.

**Figure 5.**Influence of the superheat degree on the solidification structure (

**a**–

**d**): solidification structure morphology at superheat degrees of 15, 25, 35, and 45 K, respectively; (

**e**–

**g**): changes in equiaxed crystal ratio, grain number, and average grain radius with the superheat degree, respectively.

**Figure 6.**Influence of the casting speed on the solidification structure (

**a**–

**d**): solidification structure morphology at casting speeds of 1.8, 1.9, 2.1, and 2.3 m/min, respectively; (

**e**–

**g**): changes of equiaxed crystal ratio, grain number, and average grain radius with casting speed, respectively.

**Figure 7.**Influence of the casting speed on the solidification structure (

**a**–

**d**): solidification structure morphology at specific water flows of 0.30, 0.35, 0.45, and 0.51 L/Kg, respectively; (

**e**–

**g**): changes of equiaxed crystal ratio, grain number, and average grain radius with specific water flow, respectively.

**Figure 8.**Low-power images of round billet samples produced according to the (

**a**) original process, (

**b**) scheme I, (

**c**) scheme II, and (

**d**) scheme III, where the casting billet diameter is 178 mm.

Element | Mass Fraction (wt %) | Liquidus Slope in Binary Fe-X System | Partition Coefficient | Self-Diffusion Coefficient (m^{2}/s) |
---|---|---|---|---|

C | 0.255 | −84.9 | 0.23 | 14.7 × 10^{−9} |

Si | 0.25 | −17.9 | 0.65 | 1.4 × 10^{−9} |

Mn | 0.48 | −3.3 | 0.45 | 1.6 × 10^{−9} |

P | 0.01 | −32.6 | 0.09 | 3.1 × 10^{−9} |

V | 0.10 | −36.7 | 0.98 | 11.0 × 10^{−9} |

S | 0.001 | −5.1 | 0.01 | 0.7 × 10^{−9} |

Cr | 0.50 | −0.6 | 0.47 | 1.6 × 10^{−9} |

Mo | 0.75 | −5.7 | 0.80 | 1.1 × 10^{−9} |

Parameter | Value |
---|---|

Crystallizer length (mm) | 900 |

Crystallizer water volume (L/min) | 1700 |

Cast billet size (mm) | Φ178 |

Superheat degree (K) | 40 |

Casting speed (m/min) | 1.9 |

Specific water flow (L/Kg) | 0.64 |

Cooling water ratio in the secondary cooling segment | 24:17:16:13 |

Continuous Casting Process Plan | Superheat Degree (K) | Casting Speed (m/min) | Specific Water Flow (L/Kg) |
---|---|---|---|

Original process | 40 | 1.9 | 0.64 |

Scheme I | 30 | 2.0 | 0.40 |

Scheme II | 25 | 2.1 | 0.35 |

Scheme III | 35 | 1.9 | 0.45 |

**Table 4.**Low-power test results under the equiaxed crystal ratios of cast billet samples produced according to different schemes.

Scheme | Original Process | I | II | III |
---|---|---|---|---|

Equiaxed crystal ratio (%) | 37.0 | 41.8 | 45.2 | 39.6 |

Improvement (%) | 0 | 4.8 | 8.2 | 2.6 |

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**MDPI and ACS Style**

Zhai, Y.; Pan, K.; Wu, D.
Acquiring High-Quality Oil Casing Steel 26CrMoVTiB under Optimal Continuous Casting Process Conditions. *Metals* **2019**, *9*, 993.
https://doi.org/10.3390/met9090993

**AMA Style**

Zhai Y, Pan K, Wu D.
Acquiring High-Quality Oil Casing Steel 26CrMoVTiB under Optimal Continuous Casting Process Conditions. *Metals*. 2019; 9(9):993.
https://doi.org/10.3390/met9090993

**Chicago/Turabian Style**

Zhai, Yingying, Kefeng Pan, and Dapeng Wu.
2019. "Acquiring High-Quality Oil Casing Steel 26CrMoVTiB under Optimal Continuous Casting Process Conditions" *Metals* 9, no. 9: 993.
https://doi.org/10.3390/met9090993