The industrial definition of straight seam steel pipe is a steel pipe formed by a weld seam parallel to the longitudinal direction of the steel pipe. Longitudinal steel pipe can usually be divided into metric electric welded steel pipe, electric welded thin-walled pipe, cooling oil pipe for transformers, etc. In the introduction of straight seam welded pipe production process is simple, high production efficiency, low cost, the development of faster. The industrial strength of spiral welded pipe is generally higher than the straight seam welded pipe, if you can use a narrower billet to produce a larger diameter welded pipe, we can also use the same width of the billet to produce a different diameter welded pipe. However, compared with the same length of straight seam pipe, the length of the welded seam if increased by 30 to 100%, and the production speed is lower.

Straight fung steel pipe is a general welded pipe used to transport low pressure fluids. Made of Q195, Q215A, Q235A steel, Q235B plain carbon. Steel pipe to be hydrostatic, bending, flattening and other experiments, there are certain requirements for surface quality, usually delivery length of 4-12m, often required to fixed (or times the length) delivery. The specification of welded pipe is expressed in nominal caliber (mm or inch) nominal caliber is different from the actual, welded pipe according to the specified wall thickness of ordinary steel pipe and thickened steel pipe two.

Straight seam steel pipe dense out of the furnace and the difference between the back of the furnace

1.Straight seam steel pipe furnace

Furnace is a common process in the processing of the preparatory heat treatment process. Most of the machine parts and work, mold blanks after the furnace, can eliminate the internal stress and composition of the cast, forged and welded parts of the organizational heterogeneity; can improve and adjust the mechanical properties of straight seam steel pipe, ready for the next process organization. Performance requirements are not high, less important parts and some ordinary castings, weldments, furnace can be used as the final heat treatment.

Longitudinal steel pipe furnace is the steel pipe temperature to the appropriate strength, holding time, and then slowly cooled to obtain close to the equilibrium organization of the heat treatment process. The purpose of the furnace is to uniform chemical composition, improve mechanical properties and process performance, eliminate or reduce internal stress and prepare for the final heat treatment of parts.

Straight seam steel pipe furnace technology is quite diverse, according to the heating intensity can be divided into two categories: one is in the critical strength (Ac3 or Ac1) above the furnace, also known as phase change recrystallization furnace. Including complete furnace, incomplete furnace, isothermal furnace, spheroidal furnace and diffusion furnace, etc.; the other category is below the critical strength (Ac1), also known as small pressure furnace. Including recrystallization furnace, stress relief and hydrogen removal furnace. According to the cooling method can be divided into continuous cooling out of the furnace and isothermal out of the furnace.

2.Straight seam steel pipe dense and back to the furnace

Straight seam steel pipe dense and back to the furnace is a very important heat treatment process, the process is very widely used. Densification can significantly improve the strength and hardness of straight seam steel pipe. If you then with a different strength of the furnace, you can eliminate (or reduce) the dense stress, but also to get the strength, hardness and toughness to meet the different requirements. Therefore, the dense and back to the furnace is inseparable from the two heat treatment process.

2.1straight seam steel dense

Dense is to heat the steel above the critical point, holding after cooling at a rate greater than the critical cooling rate (Vc) to get three or ingestion of good organization of the heat treatment process.

2.2Straight seam steel back to the furnace

Furnace is the dense steel temperature rise to a certain strength below the A1 point after holding for a certain period of time, in an appropriate manner cold to room temperature heat treatment process. It is the next heat treatment process immediately after the dense, while determining the organization and performance of the steel pipe in use, related to the service life of the workpiece, so it is a key process.

The main purpose of the furnace is to reduce or eliminate the dense stress; to ensure the corresponding tissue transformation, so that the size and performance of the workpiece is stable; to improve the thermal and plasticity of straight seam steel pipe, choose a different furnace strength, to obtain the appropriate combination of hardness, strength, plasticity or toughness to meet the performance requirements of different workpieces.

Cangzhou Shenlong Pipe Manufacturing Co., Ltd. is a professional manufacturer, processor and seller of all kinds of steel pipes and pipe fittings, with production base in Cangzhou, Hebei Province. The production base is located in Cangzhou, Hebei Province, China. It was built in 1992 and covers an area of more than 60,000 square meters, with more than 200 employees (including 30 inspectors) and an annual production capacity of about 150,000 tons of steel pipes and 40,000 tons of pipe fittings.