Local heat treatment method for primary and secondary heating, regulating and controlling residual stress

A technology of local heat treatment and residual stress, applied in the field of heat treatment, can solve the problems of stress corrosion cracking of welded joints, uneven microstructure of welded joints, and difficulty in eliminating residual stress of welding, etc., to reduce labor intensity, easy operation, and reduce construction. effect of cycles

Active Publication Date: 2020-06-16
CHINA UNIV OF PETROLEUM (EAST CHINA)
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  • Application Information

AI Technical Summary

Problems solved by technology

The main contradictions at present are: First, the microstructure of the welded joint is not uniform, and there are microscopic defects inside, such as element segregation or metal compounds (such as carbide and δ phase), which generate microscopic stress concentration and provide a driving force f

Method used

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  • Local heat treatment method for primary and secondary heating, regulating and controlling residual stress
  • Local heat treatment method for primary and secondary heating, regulating and controlling residual stress
  • Local heat treatment method for primary and secondary heating, regulating and controlling residual stress

Examples

Experimental program
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Effect test

Embodiment example 1

[0083] Such as Figure 1~3 , a super-large pressure vessel has a cylinder thickness of 50mm and a diameter of 40m. The reinforcing plate is a "circular" reinforcing plate with a thickness of 120mm and a diameter of about 4.2m. The width of the main heating belt is 600mm, the distance between the main and auxiliary heating belts is 400mm, the width of the auxiliary heating belt is 400mm, and the maximum temperature of the auxiliary heating is 500°C. Numerical simulation is carried out according to the heat treatment conditions and related inputs. Only the main heating method, that is, "bull's eye" heating, is used to obtain the stress cloud distribution after the heating is completed as follows: figure 2 shown. Depend on figure 2 It can be seen that a large compressive stress is generated on the top and bottom of the reinforcing plate, and the distance from the weld seam is about 600mm. On this basis, the local heat treatment method of primary and secondary cooperative he...

Embodiment example 2

[0085] Such as figure 1 , establish an axisymmetric model, the size of the closed weld of the cylinder is φ20000×50×92000, V-shaped groove, a total of 60 welds. The width of the main heating belt is 400mm, the distance between the main and auxiliary heating is 300mm, the width of the auxiliary heating belt is 300mm, and the holding temperature of the auxiliary heating is 300°C. Welding and heat treatment process analysis of body closing welds is carried out by using numerical simulation method. The local heat treatment method of primary and secondary heating is adopted. Output the axial and hoop stress distribution of the P1 path near the inner wall weld of the closing weld of the cylinder, as shown in the figure. Figure 4 (a) The ordinate indicates the axial stress along the P1 path of the inner wall of the closed weld of the cylinder, and the abscissa indicates 30mm from both sides of the weld; Figure 4 The ordinate in (b) represents the hoop stress along the P1 path of...

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Abstract

The invention relates to the technical field of heat treatment, and provides a local heat treatment method for primary and secondary heating, regulating and controlling residual stress. The local heattreatment method comprises the steps that a primary heating belt is applied to a welding line, the welding line microstructure and hardness are regulated and controlled, so that the structure is uniform, and microcosmic residual stress is regulated and controlled; and a secondary heating belt is applied at the distance from the welding line, compression stress is generated on the inner surface ofthe welding line, and macroscopic compression stress is regulated and controlled. No rib plates are used for deformation, and the maximum deformation is transferred to a non-welding line area; by applying the secondary heating and strictly controlling primary and secondary heating time interval, the welding residual stress can be greatly regulated and controlled while the structure is improved; and the local heat treatment effect can reach the optimal, lesser tensile stress and even pressure stress is generated on the inner surface of the welding line, and the problem of leakage due to the fact that corrosion and cracking are generated at welding lines of large equipment is fundamentally solved.

Description

technical field [0001] The invention relates to the technical field of heat treatment, in particular to a local heat treatment method for primary and secondary heating to regulate residual stress. Background technique [0002] As an important technology for major equipment manufacturing and safety, heat treatment is also a major problem. In petrochemical, nuclear power and other fields, pressure vessels, as key core equipment, are the main places to realize heat and mass transfer chemical reactions, and their in-service safety is of great significance. At present, my country's pressure vessels are constantly developing in the direction of large diameter, ultra-thickness, and ultra-length in terms of size, and the size continues to break through world records. The stress corrosion cracking (SCC) problem of welded joints has become the main reason for the failure of petrochemical and nuclear power equipment. [0003] Due to the limitation of the volume of the heat treatment ...

Claims

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Application Information

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IPC IPC(8): C21D11/00C21D9/50C21D1/42
CPCC21D1/42C21D9/50C21D11/00Y02P10/25C21D2221/00
Inventor 蒋文春金强谷文斌涂善东
Owner CHINA UNIV OF PETROLEUM (EAST CHINA)
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