Hot expansion steel pipe is a type of steel pipe is made by hot expansion process. Hot expansion process is a popular choice to manufacture large diameter steel pipes, such as 660mm, 762mm, and 914mm, etc. So what's the advantages and disadvantages of hot expansion steel pipes.
Advantages of Hot expansion steel pipes
1. Improving mechanical properties: Hot expansion process can effectively eliminate internal stress, significantly improving mechanical properties of steel pipes.
Reducing hardness and improving plasticity: After the steel pipe undergoes hot expansion process, the hardness will decrease, and the plasticity will increase, which is convenient for cutting and processing.
2. Flexible specification choice: Hot expansion process can produce multiple dimensions of steel pipes. Non-standard dimensions steel pipe also can be produced.
Disadvantages of Hot expansion steel pipes
1. After hot expansion, non-metallic inclusions (mainly sulfides and oxides, with silicates) inside the hot expansion steel pipe are compressed into thin sheets, results in a layering condition. Layering greatly deteriorates the tensile function of hot expanded steel pipes along the thickness direction, and there is a possibility of interlayer tearing during weld shrinkage. The local strain caused by weld shrinkage often reaches multiple times the yield point strain, which is much larger than the strain caused by load.
2. Residual stress caused by uneven cooling. Residual stress is the stress that self balances inside without external force. Various types of hot expanded steel pipes have this type of residual stress, and usually the larger the cross-sectional size of the steel, the greater the residual stress. Although residual stress is self balanced, it still has corresponding interference on the function of steel components under external forces. It will cause adverse effects in areas such as deformation and impact resistance.
In summary, although hot expansion steel pipes have multiple advantages, they also have disadvantages. Therefore the using of hot expansion steel pipes should depend on specific application needs.
