HPb58-2 brass has good mechanical properties, processing performance and corrosion resistance, and is widely used in the production of sanitary products, water supply and drainage pipes, medals, serpentine pipes, condenser pipes, bullet shells and various complex shapes of punching products and small hardware. Wait. Brass has good corrosion resistance, but is more sensitive to stress corrosion cracking, especially brass with a zinc content greater than 15% (mass fraction) has a high sensitivity to stress corrosion cracking. Therefore, the brass needs to be relieved after processing to reduce the stress corrosion cracking tendency; in terms of corrosive media, brass has a greater sensitivity to stress corrosion cracking of sulfur-containing corrosive media, such as corrosive elements in the environment The presence of sulfur, oxygen, chlorine, etc., will accelerate the occurrence of stress corrosion cracking.

According to the results of fracture analysis, metallographic examination and energy spectrum analysis, there is no obvious macroscopic deformation of the fracture of the angle valve, the crack source is located on the inner surface, the crack is bifurcated, the fracture microscopically shows the cleavage brittle fracture characteristics, and the fracture surface corrosion products There are corrosive elements sulfur, oxygen, chlorine, etc. These characteristics indicate that the cracking of angle valves is a typical stress corrosion cracking. Stress corrosion cracking needs to meet two conditions, one is corrosive medium, and the other is the effect of stress, especially tensile stress, so it can be inferred that there is a certain tensile stress inside these cracked angle valves. Some sources point out that such tensile stress often comes from welding, cold working, heat treatment and assembly processes.

The failure of the angle valve is a typical stress corrosion cracking. The excessive stress of the angle valve assembly is the main cause of the stress corrosion cracking. It is recommended that the assembly strength should be controlled when assembling the brass angle valve to avoid leaving excessive internal stress in the angle valve and causing early failure of the angle valve.