Views: 3 Author: Site Editor Publish Time: 2021-06-21 Origin: Site
Stainless steel materials are basically corrosion-resistant. At the same time, compared with other metal products, the corrosion resistance is better. Compared with stainless steel square tube, the corrosion resistance is needless to say. However, after long-term use, corrosion and rust can not be avoided, and there are many factors that damage the corrosion resistance, not only caused by improper treatment, The basic elements are related to each other, so it is difficult to know what the basic elements are when each product is corroded and rusted.
I、 Environmental factors
It mainly refers to the physical, chemical and electrochemical properties of the ring mirror, such as multi-component, concentration, temperature, pressure, acidity and conductivity. These parameters are closely related to the whole corrosion process of stainless steel pipe. Therefore, when analyzing the corrosion failure of stainless steel square pipe, we must first find out the medium conditions leading to corrosion.
II、 Basic elements of materials
As we all know, the whole corrosion process of stainless steel square tube is the whole process of chemical or electrochemical reaction between the ring mirror medium and the outer surface or interface of steel tube raw materials, so stainless steel material is a necessary and important part of the whole corrosion process. From the perspective of materials, the following aspects deserve special attention:
1. The smelting quality of stainless steel square tube raw materials. It mainly refers to the chemical composition of steel pipe raw materials, non-metallic inclusions, shrinkage cavity, segregation, slag inclusion and other conditions during pouring, as well as white spots and other defects that may be caused during the whole cooling process.
2. The production and processing quality of stainless steel seamless pipe mainly refers to the defects such as intergranular oxidation (overburning), folding, pressing iron oxide scale, delamination, banded structure, overheating and inhomogeneity of structure, which may be caused in the whole heating process during rolling, forging and extrusion, and the microcracks which may be caused during rapid cooling.
3. Improper heat treatment process or numerical control flame cutting of stainless steel seamless steel tube mainly refers to the defects caused by overheating or Overburning of temperature, coarse grain, decarburization, carburization, quenching crack, temper brittleness, failure to temper after quenching, unsuitable microstructure and improper sensitization solution caused by excessive temperature, There are also the basic elements of thermal processing technology such as improper numerical control flame cutting.
III、 Basic elements of structure design and manufacturing of mechanical equipment
1. The basic elements of design in the structural design of mechanical equipment should avoid stress concentration, residual liquid and other non-standard conditions in the structural design of mechanical equipment, and the consistency of raw materials and ring mirror should be considered in the selection of mechanical equipment materials.
2. The basic elements of stainless steel square pipe production and processing in the whole process of mechanical equipment production and processing, special attention should be paid to the external surface defects such as knife marks, scratches, burrs, partial overheating and grinding cracks caused by cold processing (such as turning, planing, milling, grinding, etc.) to the external surface of mechanical equipment, and special attention should also be paid to the pickling, grinding and other defects of stainless steel seamless pipe Hydrogen embrittlement caused by electroplating. Special attention should be paid to the root crack, liquid metal embrittlement, uneven microstructure, residual stress not eliminated after welding, undercut of weld, poor welding process, mismatch between welding rod and raw material, etc. Because the installation process is not standard, it may lead to stress concentration, or too tight with each other, resulting in additional stress and dislocation and other defects.
There are many factors that damage the corrosion resistance of stainless steel seamless square tube and cause corrosion and rusting. Even if the influence on it is not great, it also has an impact on it. Therefore, in order to reduce the destructive force on the tube and prolong the service life, the above factors have many aspects, even if the influence on it is not great, I hope you can do a good match in the production and use of the process.