What are the common defects and causes of seamless steel tubes?

Seamless steel tubes, as an indispensable material in modern industrial fields, have a crucial impact on the safety and stability of various engineering projects in terms of their quality and performance. If defects occur during the use of seamless steel tubes, it will undoubtedly have a fatal impact on the quality of our products. Therefore, understanding the defect characteristics and causes of seamless steel tubes is of great significance for improving the quality and effectiveness of seamless steel tubes.

1. Cracks and fissures: Cracks and fissures are one of the most common defects in seamless steel tubes. The causes of cracks are diverse, mainly including poor steel quality, improper heating of tube blanks, excessive deformation pressure, and other factors.

2. Scratches and abrasions: Scratches and abrasions may be caused by residual iron oxide scale on the steel tube, insufficient or uneven strength and hardness of the mould, cracking and wear of the mould, poor hammer head, sharp edges and corners in the transition part of the hammer head damaging the mould, etc.

3. Trembling mark: The causes of trembling mark include incomplete cleaning during the pickling process, uneven annealing performance, and unreasonable use of core rods and moulds during the drawing process.

4. Peeling: In addition to the quality of the raw material tube blank, the causes of skin curling may also include improper adjustment of perforation machine parameters, low perforation temperature, sticking of steel at the top, and accumulation of oxide scale.

5. Matte surface: The main reason for the formation of hemp surface is the pitting corrosion during acid washing, and the excessive thickness and straightening of the oxide scale after annealing, which is pressed into the surface of the steel tube to form hemp surface; The storage environment of steel tubes is humid, and even spot rust may occur after water ingress, forming a rough surface after removing the rust spots.

6. Pits: The formation of pits is due to the pressure of iron oxide scale or other hard dirt on the surface of the steel tube during the pulling or straightening process, or the peeling off of the raised skin that originally existed on the surface of the steel tube.

7. Decarbonisation of oxide scale: The main reasons for decarburisation are improper temperature and time control during the heat treatment process of steel tubes, chemical reactions between the steel tube surface and atmosphere, and poor raw material measurement.

8. Scratches: Scratches are a common defect in the production of cold drawn seamless steel tubes, which are usually caused by improper operations during annealing, lifting, or straightening processes.

9. Stranding injury: Stranding injury is usually caused during the straightening process due to improper adjustment of the straightening machine roller angle, excessive pressing amount, severe wear of the straightening roller, and other situations.

Zhangjiagang Huagang Industrial Co., Ltd. has been established for nearly 20 years, strictly controlling raw materials and selecting high-quality round steel from large factories. Through years of optimising and summarising production processes, reasonable setting of process parameters such as heating temperature and deformation pressure ensures the stability and accuracy of process operations. Regularly inspect and maintain production equipment to ensure its normal operation and stable performance. Establish a comprehensive quality inspection and monitoring system to monitor and inspect the entire production process of seamless steel tubes. At the same time, strengthen management, strictly standardise operating procedures, effectively reduce the occurrence of defects in seamless steel tubes, and improve the quality and effectiveness of seamless steel tubes.