Seamless steel pipes are widely utilized across various industries, including construction, automotive, petroleum, aviation, chemicals, boilers, and the military, owing to their exceptional performance. They play a pivotal role in the economic development of the entire nation. However, in recent years, while promoting national economic growth, seamless steel pipes in China have also encountered several issues. Among these, cracking in seamless steel pipes remains a persistent concern for the steel pipe industry. Cracks during production not only result in raw material wastage but may also lead to decreased production efficiency and subsequent delays in production schedules. Furthermore, cracks in seamless steel pipes during use can cause significant property damage and even casualties. Additionally, due to the complexity of seamless steel pipe production process parameters, the cause of cracking often goes undetected promptly when it occurs.
Research into the causes of cracking in seamless steel pipes has revealed the following:
1. Defects in raw materials significantly impact the cracking of seamless steel pipes. Studies have shown that the primary type of non-metallic inclusion in cracked seamless steel pipes is ring oxide inclusions (Type D). When the ring oxide level exceeds Grade 2, it has a notable effect on steel pipe cracking. Chemical composition segregation is primarily manifested as uneven carbon element distribution and localized carbon aggregation. This phenomenon results in uneven mechanical properties within the steel pipe, leading to cracks due to internal stress during processing.
2. The metallurgical structure also significantly impacts the cracking of seamless steel pipes. Results indicate that the presence of a banded structure plays a crucial role in steel pipe cracking, particularly when the banded structure is at Grade 4 or above. Additionally, the Widmanstätten structure has a certain influence on steel pipes. Experiments have demonstrated that when the Widmanstätten structure reaches Grade 3 or above, it significantly affects the cracking of seamless steel pipes. Abnormal metallurgical structure morphology is another critical cause of steel pipe cracking. Experiments show that abnormalities in the metallurgical structure are mainly characterized by coarse grains, uneven structure, and abnormal tissue composition.
3. Based on different cracking causes, corresponding preventive or improvement measures are proposed. For non-metallic inclusions, high-quality refractory mold protection slag or suitable deoxidizers can be selected, and strict control should be exercised during the smelting and pouring processes to minimize the incorporation of non-metallic inclusions. For component segregation, the content of other elements prone to segregation, apart from carbon, can be controlled, or the pouring temperature can be reduced, or electromagnetic stirring can be employed to prevent segregation. Both banded and Widmanstätten structures can be eliminated through normalizing or annealing processes. Moreover, to prevent banded structures, segregation should be avoided. Cracking in seamless steel pipes due to abnormal metallurgical structures is primarily addressed by refining the specific parameters or methods of heat treatment.
Threeway Steel is known as a professional supplier engaged in manufacturing and distributing a wide range of steel pipe, and our headquarter located the central part of China – Hunan and six associated factories throughout China.
Threeway Steel is known as a professional supplier engaged in designing, manufacturing and distribution of a wide range of steel products with the headquarter located the central part of China – Hunan and six associated factories throughout China.
Threeway Steel is known as a professional supplier engaged in designing, manufacturing and distribution of a wide range of steel products with the headquarter located the central part of China – Hunan and six associated factories throughout China.
Threeway Steel is known as a professional supplier engaged in designing, manufacturing and distribution of a wide range of steel products with the headquarter located the central part of China – Hunan and six associated factories throughout China.
Threeway Steel is known as a professional supplier engaged in designing, manufacturing and distribution of a wide range of steel products with the headquarter located the central part of China – Hunan and six associated factories throughout China.
