MENU

/
/
Influence of annealing temperature on the performance of used welded pipe equipments

Influence of annealing temperature on the performance of used welded pipe equipments

  • Sort:Information
  • Auth:
  • Source:
  • Release time:2022-03-09 11:30
  • Pvs:

【概要描述】We know that the welding process of used welded pipe equipments will cause work hardening and welding stress during the forming and welding process. If the annealing temperature is low, the stress and hardening cannot be fully eliminated, so the strength of the welded pipe after annealing is high but the plasticity is poor. With the increase of the annealing temperature, the stress and hardening are gradually eliminated, so that the strength of the welded pipe is reduced and the plasticity is improved.

Influence of annealing temperature on the performance of used welded pipe equipments

【概要描述】We know that the welding process of used welded pipe equipments will cause work hardening and welding stress during the forming and welding process. If the annealing temperature is low, the stress and hardening cannot be fully eliminated, so the strength of the welded pipe after annealing is high but the plasticity is poor. With the increase of the annealing temperature, the stress and hardening are gradually eliminated, so that the strength of the welded pipe is reduced and the plasticity is improved.

  • Sort:Information
  • Auth:
  • Source:
  • Release time:2022-03-09 11:30
  • Pvs:
Detail

The test material is ST14 cold-rolled strip produced by Baosteel, and the chemical composition is shown in Table 1.

 

Used welded pipe equipments

 

We know that the welding process of used welded pipe equipments will cause work hardening and welding stress during the forming and welding process. If the annealing temperature is low, the stress and hardening cannot be fully eliminated, so the strength of the welded pipe after annealing is high but the plasticity is poor. With the increase of the annealing temperature, the stress and hardening are gradually eliminated, so that the strength of the welded pipe is reduced and the plasticity is improved.

 

But why does the plasticity start to decrease when the annealing temperature exceeds 800℃? From the iron-carbon phase diagram, we know that in this temperature range, the material is in the two-phase region of ferrite and austenite, and the original structure is partially transformed into austenite, but some ferrite has not been transformed. It can be known from the calculation that about 10% of the cold deformation of the experimental material occurs during the forming of the welded pipe; due to the small degree of cold deformation, the material rarely recrystallizes during annealing. These untransformed ferrites grow up during the annealing process, and the higher the temperature, the coarser the grains, and these coarse ferrite grains remain after annealing and cooling. On the other hand, the austenite formed by heating to a high temperature forms fine ferrite grains after cooling, which in turn causes uneven grain size, thereby reducing both strength and plasticity.

 

When the annealing temperature is 920℃, the welded pipe has good strength and plasticity at the same time. During the welding process of used welded pipe equipments, not only a small amount of unbalanced weld structure such as martensite is formed in the weld, but also the grains in the heat-affected zone are coarse, which all have an adverse effect on the performance. Only by heating to a temperature above Ac3 to make the structure all austenitic can these effects be eliminated, so that the structure of the weld and the base metal tends to be consistent, that is, a fine structure is obtained, thereby improving the mechanical properties of the welded pipe.

 

Problems that should be paid attention to in production

If the user requires the welded pipe to have good plasticity, but does not require too high strength, we can use the temperature between 700 ~ 800℃ for continuous annealing. In this case, the temperature range is wide, and it is easy to control the production process.

 

If the user requires the welded pipe to have high strength and good plasticity at the same time, then annealing between 700 and 800℃ cannot meet the requirements. Because in the high-frequency welding process, due to the combined effect of skin effect, proximity effect and heat conduction, the peak temperature of welding thermal cycle is distributed in gradient at the opening edge of the tube blank, and melting zone, partial melting zone and overheating structure zone appear. feature area. Therefore, the unbalanced structure and coarse structure around the weld have adverse effects on the performance of the welded pipe; to eliminate these effects, the heat treatment temperature must be increased to above Ac3. But the temperature should not be too high, otherwise the performance will deteriorate.

 

This requires that the annealing temperature be strictly controlled in the actual production process of used welded pipe equipments, so that the annealing temperature is guaranteed to be around 920℃. On the other hand, fast cooling is required in the initial stage of cooling, which requires the circulating water to have sufficient cooling capacity to ensure a uniform and refined structure after heat treatment, thereby ensuring the quality of the product.

 

The experiment was carried out in a continuous annealing furnace, and the experimental results are shown in the figure below. It can be seen that when the annealing temperature is low, the strength of the sample is high, but the plasticity is poor. With the increase of annealing temperature, the tensile strength decreased gradually and the elongation increased continuously, which was mainly because the stress and hardening in the welded pipe were gradually eliminated during the annealing process. But after the annealing temperature exceeds 800℃, not only the strength continues to decrease, but also the elongation begins to decrease.

 

Used welded pipe equipments

 

In conclusion

When the used welded pipe equipments are used to make pipes, if the welded pipe is required to have good plasticity and general strength, the temperature between 700 and 800℃ can be used. However, when the welded pipe is required to have high strength and good plasticity at the same time, it is recommended to use a temperature of 920℃ and make the water temperature of the cooling water tank lower to ensure a certain cooling rate.

 

Our company has many brands and wide resources, there is always one suitable for you. You only need to tell us your pipe manufacturing needs, our company will provide you with used welded pipe equipments that really suits your needs, welcome new and old customers to come to consult and order.

关键词:

More News

Solutions to difficulties in thick-walled pipe forming of directly forming to square pipe mill (1)
Solutions to difficulties in thick-walled pipe forming of directly forming to square pipe mill (1)
Solutions to solve the difficulties in forming thick-walled tubes of directly forming to square pipe mill include special forming unit solutions, rough forming pass solutions, fine forming pass solutions and comprehensive solutions. Let me introduce the solution to the difficult forming of thick-walled tube(1).
Detail
Solutions to solve the difficulties in forming thick-walled tubes of directly forming to square pipe mill include special forming unit solutions, rough forming pass solutions, fine forming pass solutions and comprehensive solutions. Let me introduce the solution to the difficult forming of thick-walled tube(1).
Solution for thick wall tube forming of used round pipe to square pipe machines(2)
Solution for thick wall tube forming of used round pipe to square pipe machines(2)
In the welded pipe industry, people generally regard welded pipes with a wall thickness to outside diameter (thickness-to-diameter ratio) of 12%≤t/D≤18% as thick-walled pipes. Difficulties in used round pipe to square pipe machines, clearly put forward the adjustment methods of thick-walled tube forming.
Detail
In the welded pipe industry, people generally regard welded pipes with a wall thickness to outside diameter (thickness-to-diameter ratio) of 12%≤t/D≤18% as thick-walled pipes. Difficulties in used round pipe to square pipe machines, clearly put forward the adjustment methods of thick-walled tube forming.
Solutions to difficulties in thick-walled pipe forming of directly forming to square pipe mill (1)
Solutions to difficulties in thick-walled pipe forming of directly forming to square pipe mill (1)
Solutions to solve the difficulties in forming thick-walled tubes of directly forming to square pipe mill include special forming unit solutions, rough forming pass solutions, fine forming pass solutions and comprehensive solutions. Let me introduce the solution to the difficult forming of thick-walled tube(1).
Detail
Solutions to solve the difficulties in forming thick-walled tubes of directly forming to square pipe mill include special forming unit solutions, rough forming pass solutions, fine forming pass solutions and comprehensive solutions. Let me introduce the solution to the difficult forming of thick-walled tube(1).
Analyzing the roll life of a used ERW tube mill
Analyzing the roll life of a used ERW tube mill
In the production of used ERW tube mills, the roll is the key and important special tool. Roll consumption is also a key tool for manipulating product costs. In addition, the normal operation of the roll will directly affect the output and quality of welded pipe manufacturing. Therefore, welded pipe manufacturers attach great importance to and strive to improve the service life of the roll.
Detail
In the production of used ERW tube mills, the roll is the key and important special tool. Roll consumption is also a key tool for manipulating product costs. In addition, the normal operation of the roll will directly affect the output and quality of welded pipe manufacturing. Therefore, welded pipe manufacturers attach great importance to and strive to improve the service life of the roll.
Contact information
Tel: +86-13392281699
Wechat: 13392281699
Email: zty@usedpipemill.com
Company address:No. A99, East Lecong Avenue, Lecong Town, Foshan City, Guangdong Province

Recommendation

Online Inquiry

留言应用名称:
底部留言
描述:

LINK

Contact Us

Tel (wechat): 13336487288
Wechat:+86 13336487288

WhatsApp:+86 13336487288
Email: zty@usedpipemill.com

Address: No. A99, Lecong Avenue East, Lecong Town, Foshan City, Guangdong Province

QRCODE

Copyright 0 2021 jinyujie. 粤ICP备13051810号 Powerby:  300.cn