The seamless pipe refers to the steel pipe which is perforated by the whole round steel and has no weld seam on the surface. The seamless pipe has the size of schedule 40 pipe. It is mainly used as petroleum geological drilling pipe, octg casing, cracking pipe for petrochemical industry, boiler pipe, bearing pipe and high-precision structural steel pipe for automobile, tractor and aviation. The material of the seamless pipe includes stainless steel seamless pipe, alloy seamless pipe, etc.
No matter what material the seamless steel pipe is made of, cracking is inseparable from the influence of the composition, structure and process of the material. Billets with poor quality are also prone to cracking, such as steel ingot quality problems, and steel ingots containing air bubbles are easy to crack when formed. The internal cracking or external cracking of the seamless steel pipe may be caused by five harmful elements in terms of chemical composition. In the process, if it is overheated or over-burned, it will cause cracking, cracks caused by low-temperature rolling, and hot brittle cracks.
1. The raw material factors of seamless steel pipes: tube blanks with poor quality will have internal and external warping, scarring, cracks, etc.;
2. Heating temperature factor: The first important process of seamless steel pipe production is heating, and poor heating (uneven, insufficient temperature, etc.) will cause internal warping, etc.;
3. Equipment debugging factors: starting from the furnace, each equipment component will affect the final quality of the seamless steel pipe. For example, the scraping of the equipment parts will cause the outer skin and pits; if the punching machine is not smooth, it will cause the head of the tube blank to be drenched in water and it will be difficult to bite or the head will be warped.
4. Seamless steel pipe production process issues: process issues are also quite complicated, there are adjustment problems, equipment failure problems, and seamless steel pipe quality problems caused by the wear of process components (plugs, guide plates, rolls, etc.).
Therefore, there are dozens of possible reasons for the occurrence of a seamless steel pipe defect. If you don't see the real thing or are not on the production site, it is often difficult to tell the specific reason. From the above analysis, it is normal for the seamless steel pipe to crack, but the reason needs to be carefully observed to find the problem.
Most of the seamless pipes produced now are hot-rolled. Because of the high temperature, the deformation resistance is relatively small. Generally, steel plates are used to complete the rectification and rolling process. In this operation process, the specific thickness of the steel plate also needs to be considered. If the requirements for accuracy are relatively low, there will be no problem with the shape of the plate, and the main focus is on control. In other words, in terms of temperature control, it is also a problem that must be considered. It can be said that the consideration of this part is also very important.
There are clear quality requirements for seamless pipes in the market, especially the requirements for different alloying elements cannot be sloppy. The harmful elements in it must be strictly controlled, and the hazards and defects of the pipeline materials after the production is completed need to be considered. For example, problems such as cracks, inner folds, outer folds, crushing, delamination, scarring, dents, etc. that may occur, must also be controlled within the agreed range to avoid quality problems.