Ningbo 180 alloy steel pipe in stock
| Alloy steel | 15crmoG | 133*18 | national standard | of large number | of large number | Electronic discussion | *** |
| Alloy steel | 15crmoG | 140*5 | national standard | of large number | of large number | Electronic discussion | *** |
| Alloy steel | 15crmoG | 140*5.5 | national standard | of large number | of large number | Electronic discussion | *** |
| Alloy steel | 15crmoG | 140*6 | national standard | of large number | of large number | Electronic discussion | *** |
| Alloy steel | 15crmoG | 140*12 | national standard | of large number | of large number | Electronic discussion | *** |
| Alloy steel | 15crmoG | 140*12.5 | national standard | of large number | of large number | Electronic discussion | *** |
Knowledge of Ningbo 180 alloy steel pipe
1. Production process and key points
The production process is as follows: billet sawing, billet heating, piercing, pipe rolling, micro tension reducing, cooling, straightening, pipe cutting, packaging and delivery.
2. Determination of process parameters and pass design
When using ￠ 120mm continuous casting billet to produce 114mm × 22mm steel pipe, the wall thickness coefficient of steel pipe is large, which makes the transverse wall thickness of steel pipe after sizing uneven, resulting in serious degree of "inner hexagon" on the inner surface of steel pipe.
In micro stretch reducing process, reducing ratio is the main factor to produce "inner hexahedron". The influence mechanism of total reducing rate and single stand reducing rate is the same. If the reduction ratio is too large, the tension coefficient will increase, and the axial flow will be intensified, while the radial flow will be weakened and the radial wall thickness will be uneven. That is to say, the larger the reduction rate of single stand means that the higher the non-uniformity of height compression and the difference of metal flow between the top and the roll gap, the more will aggravate the formation of inner polygon. When the total reduction rate is constant, increasing the number of finished frames can reduce the reduction rate of single stand. The front frame of sizing mill 5 is optimized and used. The reduction rate of each stand can be calculated by the formula. The reduction rate of the first stand depends on the size of the outer diameter before sizing. In actual production, this number is a range value, so the reducing rate of the first stand is an uncertain value.
Brief introduction of Ningbo 180 alloy steel pipe
Although the diffusion ability of hydrogen in alloy steel pipe is very strong, it is still affected by many factors such as crystal structure. For example, the diffusion coefficient of hydrogen in hCPA titanium and BCCB titanium is quite different. The diffusion coefficient of hydrogen in β titanium is several to dozens of orders of magnitude higher than that in a titanium. In addition, the diffusion rate of hydrogen is also affected by temperature and surface state. The higher the temperature, the greater the diffusion coefficient of hydrogen. Titanium has strong chemical activity and can react with oxygen rapidly at room temperature.
Therefore, the surface of alloy steel pipe is easy to be polluted by oxygen, resulting in the decrease of hydrogen absorption capacity of titanium. During the diffusion process of hydrogen in alloy steel pipe, at the temperature of hydrogen permeation, hydrogen molecules first decompose into hydrogen atoms and impact on the surface of alloy. Due to the loose structure at the grain boundary and phase boundary, hydrogen atoms preferentially diffuse at the grain boundary or phase boundary in a short distance, so that the hydrogen concentration in these two places reaches saturation in a short time. Finally, the hydrogen atom diffuses into the grain through the lattice and completes the diffusion process. Through the study of hydrogen diffusion kinetics in tigal based alloy, a similar conclusion is drawn. The alloys with different hydrogen content can be obtained by controlling hydrogen pressure, hydrogen temperature and holding time. The results show that there is no macroscopic hydrogen concentration gradient in the sample after high temperature gas charging, and hydrogen distributes uniformly in the whole thickness range. However, if there is a stress concentration, hydrogen atoms will diffuse and gather in the three-dimensional stress region under the action of stress, and a new concentration equilibrium will be achieved in the local position of the stress region.
|
