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Control method for avoiding large-thickness medium-and-high carbon steel cutting delayed cracks in winter

A technology of delayed cracking and control method, applied in the direction of heat treatment process control, manufacturing tools, gas flame welding equipment, etc., can solve the problems of waste products, influence, influence on corporate image, etc., to reduce martensitic structure, reduce stress concentration, The effect of reducing production costs

Active Publication Date: 2015-10-21
WUYANG IRON & STEEL
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0002] When producing medium and high carbon steel in winter, as the temperature gradually decreases, a large number of cutting delay cracks appear on the cutting surface after flame cutting of large thickness steel plates, which greatly increases the unplanned quantity and even produces waste products, which seriously affects the production cost and contract of the enterprise. Realization rate, for the current low-profit iron and steel industry, enterprises have a large number of unplanned, which has a very adverse impact on the production and operation environment
At the same time, the contract cannot be honored on time, which also seriously affects the image of the company in the eyes of customers, affects the competitiveness of the company's products, and has a greater adverse impact on the subsequent development of the company.

Method used

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  • Control method for avoiding large-thickness medium-and-high carbon steel cutting delayed cracks in winter
  • Control method for avoiding large-thickness medium-and-high carbon steel cutting delayed cracks in winter
  • Control method for avoiding large-thickness medium-and-high carbon steel cutting delayed cracks in winter

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0031] Embodiment 1: The control method adopts the following specific techniques.

[0032] Steel type 45#, thickness specification 120mm, composition design (by weight percentage): C 0.46%, Mn 0.75%, other components comply with GB / T711-2008 standard.

[0033] Process: (1) Normalizing in the car bottom furnace, the normalizing temperature is 860 ℃ ~ 870 ℃, the heating coefficient (holding time) 1.5min / mm, air cooling.

[0034] (2) After normalizing, the steel plate is required to be cut at a warm temperature, sheltered from the wind during cutting, and the cutting temperature is 120°C; after the steel plate is cut, it should be heated in a slow cooling pit within 2.5 hours for stress relief treatment.

[0035] (3) Stress relief treatment: the heating temperature of the slow cooling pit is 330°C, the steel plate is put into the furnace for 2 hours and then cooled to room temperature of 25°C with the furnace.

[0036] The tissue diagram of the 45# steel plate after the cut of t...

Embodiment 2

[0037] Embodiment 2: This control method adopts the following specific techniques.

[0038] Steel type 45#, thickness specification 180mm, composition design (by weight percentage): C 0.47%, Mn 0.85%, other components comply with GB / T711-2008 standard.

[0039] (1) Normalize in the car bottom furnace, the normalizing temperature is 860℃~880℃, the heating coefficient (holding time) is 1.5min / mm, and air-cooled.

[0040] (2) After normalizing, the steel plate is required to be cut at a temperature, sheltered from the wind during cutting, and the cutting temperature is 135°C; after the steel plate is cut, it is heated in a monomer furnace within 2.5 hours for stress relief treatment.

[0041] (3) Stress relief treatment: the heating temperature of the monomer furnace is 320°C, the steel plate is put into the furnace for 2.5 hours and then cooled to room temperature of 20°C with the furnace.

[0042] The tissue diagram of the 45# steel plate after the cut of the present embodimen...

Embodiment 3

[0043] Embodiment 3: This control method adopts the following specific techniques.

[0044] Steel type 45#, thickness specification 300mm, composition design (by weight percentage): C 0.47%, Mn 0.78%, other components comply with GB / T711-2008 standard.

[0045] (1) Normalize in the car bottom furnace, the normalizing temperature is 860℃~880℃, the heating coefficient (holding time) is 1.8min / mm, and air-cooled.

[0046] (2) After normalizing, the steel plate is required to be cut at a temperature, sheltered from the wind during cutting, and the cutting temperature is 135°C; after the steel plate is cut, it is heated in a monomer furnace within 2.5 hours for stress relief treatment.

[0047] (3) Stress relief treatment: the heating temperature of the monomer furnace is 350°C, the steel plate is put into the furnace for 2 hours and then cooled to room temperature of 26°C with the furnace.

[0048] The tissue diagram of the 45# steel plate after the cut of the present embodiment ...

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Abstract

The invention discloses a control method for avoiding large-thickness medium-and-high carbon steel cutting delayed cracks in winter. A high carbon steel plate is slowly cooled after normalizing treatment and flame cutting are carried out; in the high carbon steel plate, the content of C ranges from 0.45wt% to 0.47wt%, and the content of Mn ranges from 0.70 wt% to 0.85wt%; and in the normalizing treatment process, the normalizing temperature ranges from 850 DEG C to 880 DEG C, and the heat preservation time ranges from 1.5 min / mm to 2.5 min / mm. According to the method, the design of the high C content and the high Mn content is adopted, so that the martensitic structure is effectively reduced, the stress concentration caused by the heat treatment is reduced, and generation of the delayed cracks is effectively avoided. According to the method, when flame cutting is carried out, temperature waiting cutting is adopted, wind-avoiding cutting is carried out so as to decrease the cooling speed of a cutting face after the steel plate is cut, and the cut steel plate enters a slow cooling pit in time for stress treatment; generation of the martensitic structure is reduced more efficiently, the structure stress concentration is reduced, and the stress delayed cracks caused after flame cutting are avoided; and the outer-plane rate of the delayed cracks of the cutting face is controlled to be within 1%, the production efficiency is effectively improved, and the production cost is reduced.

Description

technical field [0001] The invention belongs to the technical field of steel plate surface quality control, in particular to a control method for avoiding cutting delayed cracks of large-thickness medium-high carbon steel in winter. Background technique [0002] When producing medium and high carbon steel in winter, as the temperature gradually decreases, a large number of cutting delay cracks appear on the cutting surface after flame cutting of large thickness steel plates, which greatly increases the unplanned quantity and even produces waste products, which seriously affects the production cost and contract of the enterprise. Cash rate, in view of the current micro-profit steel industry, enterprises have a large number of unplanned, which has a very adverse impact on the production and operation environment. At the same time, the contract cannot be honored on time, which also seriously affects the image of the enterprise in the eyes of customers, affects the competitivene...

Claims

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Application Information

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IPC IPC(8): C21D9/52C21D11/00C21D1/28C22C38/04B23K7/00
Inventor 谷盟森王会岭刘丹余景明宋庆吉靳兴亚张鹏云刘利香付冬阳
Owner WUYANG IRON & STEEL