Normalization heat treatment method of heavy-gauge low-alloy steel plates

A technology for normalizing heat treatment and alloy steel plates, applied in heat treatment furnaces, heat treatment equipment, furnaces, etc., can solve the problem that the performance of the center of the steel plate is difficult to meet the requirements, the improvement effect of grain size, internal stress and harmful structure is not obvious, and the performance of the steel plate Impact and other issues, to achieve the effect of high and low temperature impact energy, reduce production costs, and save alloy costs

Inactive Publication Date: 2012-10-17
WUYANG IRON & STEEL +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Most low-alloy steels are delivered in a normalized state. This heat treatment method is often used in the actual production of this steel type, but the conventional normalizing heat treatment method can only play a good role in thin steel plates. For large-thickness steel plates, after conventional normalizing heat treatment, the improvement effect of grain size, internal stress and harmful structure is not obvious, and the physical properties of the steel plate are also greatly affected, especially the performance at the center of the steel plate is very Difficult to meet requirements

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0015] The normalizing heat treatment method of the large-thickness low-alloy Q345E steel plate in this embodiment, the thickness of the steel plate is 80mm, the chemical composition of the steel plate is as follows: C: 0.16%, Si: 0.30%, Mn: 1.55%, P: 0.015%, S: 0.005%, Nb: 0.020%, Al: 0.045%, Ti: 0.002%, V: 0.006%, and the balance is Fe and unavoidable impurities.

[0016] The specific steps are:

[0017] (1) Heating: Normalizing heating temperature is 900°C;

[0018] (2) Heat preservation: heat preservation time is 1.8min / mm;

[0019] (3) Water-cooling process: after the steel plate comes out of the heating furnace, it is cooled in water in time, and the time interval from the furnace to the start of water cooling is 0.5min; it is cooled by roller transmission and header spray laminar flow, and 4~21 sets of water are opened. The upper and lower water ratio is 1 : 2.4, the control roll speed is 24m / min, the cooling rate of the steel plate is guaranteed to be 9°C / s, and the ...

Embodiment 2

[0022] The normalizing heat treatment method of the large-thickness low-alloy S355J2+N steel plate in this embodiment, the thickness of the steel plate is 180mm, the chemical composition of the steel plate is as follows: C: 0.18%, Si: 0.35%, Mn: 1.50%, P: 0.015%, S: 0.010%, Nb: 0.020%, Al: 0.045%, Ti: 0.002%, V: 0.006%, and the balance is Fe and unavoidable impurities.

[0023] The specific steps are:

[0024] (1) Heating: Normalizing heating temperature is 920°C;

[0025] (2) Heat preservation: heat preservation time is 2.0min / mm;

[0026] (3) Water-cooling process: After the steel plate comes out of the heating furnace, it is cooled in water in time, and the time interval from the furnace to the start of water cooling is 0.3min; the water tank is used for cooling, and the cooling time of the steel in water is controlled to be 1.5min. By controlling the water exchange rate of 100 per hour Tons and water temperature of 40°C, control the vertical placement of the steel plate ...

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Abstract

The invention provides a normalization heat treatment method of heavy-gauge low-alloy steel plates. The method concretely comprises the steps of heating, heat insulating and cooling. The steel plates prepared through the method of the invention comprise the following components: 0.18% or less of C, 0.50% or less of Si, 1.60% or less of Mn, 0.020% or less of P, 0.010% or less of S, 0.06% or less of Nb, 0.02-0.06% of Al, 0.03% or less of Ti, 0.08% or less of V, and the balance Fe and inevitable impurities. Different heat insulation time and cooling technologies are adopted according to different thicknesses of the steel plates, the heat insulation period is 1.8min/mm and a rolling transmission and collector spray water laminar flow mode is adopted to cool when the thicknesses of the steel plates are equal to or less than 100mm, and the heat insulation period is 2.0-2.2min/mm and a water tank cooling mode is adopted to cool when the thicknesses of the steel plates are greater than 100mm. The normalizing heat treatment technology of the invention allows the cooling intensity and the cooling speed of cores of the steel plates to be improved, the nucleation rate of the steel plates to be improved, tissues in the centers of the steel plates to be refined, the quality of the steel plates to be guaranteed and bad tissues and performances caused by uneven heavy-gauge steel plate cooling to be effectively solved, and is especially suitable for heat treatment technologies of thick steel plates.

Description

technical field [0001] The invention belongs to the technical field of heat treatment of steel plates, and in particular relates to a normalizing heat treatment method for large-thickness low-alloy steel plates. Background technique [0002] Normalizing heat treatment is a heat treatment process in which steel is heated to an appropriate temperature above Ac3 or Acm, and then cooled for a certain period of time to obtain ferrite pearlite structure. Normalizing heat treatment can refine grains, eliminate internal stress, eliminate Widmanstatten structure and Ribbon tissue. Most low-alloy steels are delivered in a normalized state. This heat treatment method is often used in the actual production of this steel type, but the conventional normalizing heat treatment method can only play a good role in thin steel plates. For large-thickness steel plates, after conventional normalizing heat treatment, the improvement effect of grain size, internal stress and harmful structure ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C21D1/28C21D9/46
Inventor 韦明李红文胡丽周宋向前吴天育贺霄
Owner WUYANG IRON & STEEL
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