Low-cost production process for Q355C steel plate

A production process, low-cost technology, applied in the field of steel plates, can solve the problems of difficult to achieve low-cost production and high price

Active Publication Date: 2020-09-04
TIANJIN IRON & STEEL GRP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Because of the requirement of impact toughness at lower temperatures, microalloying elements such as Nb and V are routinely used for microalloying in production to ensure the str

Method used

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  • Low-cost production process for Q355C steel plate
  • Low-cost production process for Q355C steel plate
  • Low-cost production process for Q355C steel plate

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0034] Steel type: Q355C; billet thickness 250mm; rolled product specification: 16mm; quantity: 8 pieces, 80.20t in total.

[0035] 1. Melting composition: C=0.17%, Si=0.30%, Mn=1.45%, P=0.015%, S=0.012%, Alt=0.025%;

[0036] The slab has a good low-magnification structure, with H content of 2.5ppm, T[O]: 20ppm, and N content of 44ppm.

[0037] 2. Soaking temperature: 1200°C; rough rolling start temperature: 1130°C; finish rolling start temperature: 950°C; final rolling temperature 840°C; ACC final cooling temperature 680°C.

[0038] 3. The distribution of rough and finish rolling passes is 7 / 7, the intermediate billet is 80mm, and the compression ratio of the intermediate billet is 5. The specific parameters are shown in Table 1.

[0039] Table 1 Embodiment 1 rolling pass situation

[0040]

[0041] 4. After the steel plate is rolled, it goes off-line for stack cooling, and the off-line temperature is 250°C.

[0042] 5. After the steel plate stack is cooled to room temp...

Embodiment 2

[0047] Steel type: Q355C; slab thickness 250mm; rolled product specification: 30mm; quantity: 7 pieces, 85.23t in total.

[0048]1. Melting composition: C=0.15%, Si=0.35%, Mn=1.51%, P=0.018%, S=0.010%, Alt=0.025%;

[0049] The low-magnification structure of the slab is good, the H content is 2.5ppm, T[O]: 22ppm; the N content is 49ppm.

[0050] 2. Soaking temperature: 1180°C; rough rolling start temperature: 1100°C; finish rolling start temperature: 910°C; final rolling temperature 840°C; ACC final cooling temperature 650°C.

[0051] 3. The distribution of rough and finish rolling passes is 7 / 7, the intermediate billet is 110mm, and the intermediate billet compression ratio is 3.7. The specific parameters are shown in Table 3.

[0052] Table 3 Example 2 rolling pass situation

[0053]

[0054] 4. After the steel plate is rolled, it goes off-line for stack cooling, and the off-line temperature is 280°C.

[0055] 5. After the steel plate stack is cooled to room temperature...

Embodiment 3

[0060] Steel type: Q355C; slab thickness 250mm; rolled product specification: 50mm; quantity: 6 pieces, 78.72t in total.

[0061] 1. Melting composition: C=0.18%, Si=0.32%, Mn=1.56%, P=0.017%, S=0.008%, Alt=0.030%;

[0062] The low-magnification structure of the slab is good, the H content is 1.8ppm, T[O]: 20ppm; the N content is 46ppm.

[0063] 2. Soaking temperature: 1160°C; rough rolling start temperature: 1090°C; finish rolling start temperature: 870°C; final rolling temperature 850°C; ACC final cooling temperature 630°C.

[0064] 3. The distribution of rough and finish rolling passes is 5 / 7, the intermediate billet is 150 mm, and the compression ratio of the intermediate billet is 3. The specific parameters are shown in Table 5.

[0065] Table 5 Embodiment 3 rolling pass situation

[0066]

[0067] 4. After the steel plate is rolled, it goes off-line for stack cooling, and the off-line temperature is 310°C.

[0068] 5. After the steel plate stack is cooled to room t...

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Abstract

The invention relates to low-cost production process for a Q355C steel plate. The Q355C steel plate comprises the following chemical components in percentage by mass: 0.11%-0.20% of C, not greater than 0.20%-0.45% of Si, 1.1%-1.6% of Mn, 0.015%-0.045% of Alt, not greater than 0.025% of P, not greater than 0.015% of S and the balance Fe; the internal quality of the steel plate is improved via converter smelting, reasonable end-point carbon content control, complete deoxygenation, white slag refining and soft blowing, calcium treatment, and continuous casting; and the internal quality of the steel plate is further improved through rough rolling and finish rolling two-phase controlled rolling, and reasonable allocation for rolling temperatures, speeds and passes. According to the low-cost production process for the Q355C steel plate, the impact toughness at 0 DEG C is improved by reducing a C content; expensive Nb and V are replaced by cheap micro-alloy element Al, so that the profit maximization is realized, and the impact toughness is further improved; and the Q355C steel plate is produced through a rolling process which is matched with the components, and the cost of a ton of steelcan be reduced by 50 yuan.

Description

technical field [0001] The invention belongs to the technical field of steel plates, in particular to a low-cost Q355C steel plate production process. Background technique [0002] Q345 grade low-alloy structural steel is one of the most basic steel types. It has a large stock and circulation in the market. Its implementation standard is GB / T 1591-2008, which was adopted on February 1, 2019. Replaced by the new version of GB / T 1591-2018. The biggest change in the new standard is the Q345 strength grade. In the new version, the Q345 grade grade is canceled and replaced by the Q355 grade. The requirement is changed to 355MPa for upper yield. Therefore, the market is facing a transition from Q345 to Q355. [0003] Q355C steel is a high-quality low-alloy structural steel. Compared with the ordinary quality grade Q355B, the P and S content requirements are lower, and at the same time it requires 0°C impact performance indicators. It is widely used in rolling stock, lifting equ...

Claims

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Application Information

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IPC IPC(8): C22C38/02C22C38/04C22C38/06C21D8/02
CPCC21D8/0226C22C38/02C22C38/04C22C38/06
Inventor 王佩鑫刘桂华张楠计艳辉徐振坤
Owner TIANJIN IRON & STEEL GRP
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