The principle of seamless steel penetration testing is simple and the method is flexible. It can detect surface opening defects in any direction at one time. It has high detection sensitivity for surface opening defects of austenitic stainless steel seamless steel pipe material workpieces. It is one of the most commonly used non-destructive testing methods. one. There are mainly the following types:
1. Classification by penetrant
According to the dye components contained in the penetrant, it is divided into three categories: fluorescence method (I), coloring method (II), and fluorescent coloring method (III).
The fluorescence method has high sensitivity but requires a black light. It is recommended for high-strength steels, crack-sensitive materials, and workpieces prone to stress corrosion cracking. The coloring method is the most widely used, and the fluorescent coloring method is rarely used.
2. Classification by penetrant removal
According to the removal method of the penetrant, it can be divided into three categories: washing type (A), post-emulsification type (lipophilic type B, hydrophilic type D) and solvent removal type (C).
The water washing type is easy to operate and has a low cost; the post-emulsification type has high sensitivity and good repeatability, but the cost is high; the solvent removal type is the most widely used.
3. Classification according to the method of applying imaging agent
According to the method of applying the developer, the developer is divided into five categories: dry powder (a), water-soluble (b), water-suspended (c), solvent-suspended (d), and self-imaging (e).
Dry powder imaging will not spread over time; water dissolution and water suspension are suitable for large-scale workpieces; solvent suspension is simple to operate; self-imaging does not use imaging agents.
4. Classification by sensitivity and type of remover
According to the sensitivity level of penetration detection, it can be divided into five categories: very low, low, intermediate, high and super high.
According to the type of remover, it is divided into three categories: halogenated solvents, non-halogenated solvents, and special application type solvents.
Generally, the IIC method is used for the site without water source and power source; the I/IIC method is used for the local detection of large workpieces; the I/IIA method is used for the workpieces with rough surface and low detection sensitivity.For the detection of large batches of workpieces, the I/IIA method is used; for the workpieces with a smooth surface and high detection sensitivity, the I/IIB/D method or the IC method is used.