Hot Rolled Steel Pipe

Hot-rolled seamless steel pipe: Hot-rolling is rolling performed above the recrystallization temperature. Hot-rolled steel pipes are divided into general steel pipes, low- and medium-pressure boiler steel pipes, high-pressure boiler steel pipes, alloy steel pipes, stainless steel pipes, petroleum cracking pipes, geological steel pipes and other steel pipes.

The main standards are GB/T5310-2008 (high pressure seamless pipe for boiler), GB/T6479-2000 (high pressure seamless steel pipe for fertilizer equipment), YB235-70 (seamless steel pipe for geological drilling), YB528-65 (oil drilling) Seamless steel pipe), GB/T9948-2006 (seamless steel pipe for petroleum cracking), etc.

The main purpose

Seamless hot-rolled steel pipes belong to the hot-rolling process of seamless steel pipes, which are mainly used in the construction industry, machinery industry (bearing sleeves, processing machinery parts), power industry, nuclear power industry, etc.

Processing technology

Hot-rolled seamless steel tubes are generally produced on automatic tube rolling mills. The solid tube is inspected and cleaned of surface defects, centered on the perforated end of the tube, and then sent to the heating furnace for heating, pierced on the piercing machine, while rotating and advancing continuously, under the action of the roller and the plug, the inside of the tube gradually becomes The cavity is formed, the capillary tube is weighed, and then sent to the automatic rolling mill to continue rolling, and finally the wall thickness is uniformed by the equalizer, and the diameter is sizing by the sizing machine to meet the specification requirements

Process overview

Round tube blank → heating → piercing → three-roll cross rolling, continuous rolling → tube stripping → sizing → cooling → billet tube → straightening → hydraulic test (or flaw detection) → marking → storage

FAQ

1. Question: What are the advantages and disadvantages of hot-rolled seamless steel pipes?

Answer: Advantages:

It can destroy the casting structure of the steel ingot, refine the grain of the steel, and eliminate the defects of the microstructure, so that the steel structure is dense and the mechanical properties are improved.

Shortcoming:

1. After hot rolling, the non-metallic inclusions (mainly sulfides and oxides, as well as silicates) inside the steel are pressed into thin sheets, and delamination (interlayer) occurs.

2. Residual stress caused by uneven cooling. Residual stress is the internal self-balanced stress without external force. Hot-rolled steel sections of various cross-sections have this kind of residual stress. Although the residual stress is self-balanced, it still affects the performance of steel components under external force. Certainly affect. For example, it may have adverse effects on deformation, stability, fatigue resistance, etc.

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