How about the corrosion resistance of stainless steel hollow spheres?
types and definitions of corrosion; A stainless steel can have good corrosion resistance in many media, but in other media, corrosion may occur due to low chemical stability. Therefore, a stainless steel cannot be resistant to all media. In many industrial applications, stainless steel can provide satisfactory corrosion resistance. According to the experience of use, in addition to mechanical failure, the corrosion of stainless steel hollow spheres is mainly manifested in: a serious form of corrosion of stainless steel is local corrosion ( Stress corrosion cracking, spot corrosion, intergranular corrosion, corrosion fatigue and crevice corrosion). These failure cases caused by local corrosion account for almost more than half of the failure cases. In fact, many failure accidents can be avoided through reasonable material selection.
metal corrosion can be divided into three types according to mechanism: special corrosion, chemical corrosion and electrochemical corrosion. The vast majority of metal corrosion in real life and engineering are electrochemical corrosion. Stress corrosion cracking (SCC) : Refers to a general term for alternating failure of stressed alloys due to the expansion of strong lines in corrosive environments. Stress corrosion cracking has brittle fracture morphology, but it may also occur in materials with high toughness. The necessary condition for stress corrosion cracking is tensile stress ( Whether it is residual stress or external stress, or both)And specific corrosive media. The formation and expansion of the pattern are roughly perpendicular to the direction of tensile stress. The stress value that causes stress corrosion cracking is much smaller than that required for material fracture without corrosive medium.
at the microscopic level, the crack passing through the grain is called the transgranular crack, while the crack spreading along the grain boundary is called the intergranular crack, when stress corrosion cracking extends to its depth ( Here, the stress on the section of the loaded material reaches its fracture stress in the air), The material is in normal crack ( In tough materials, it is usually through polymerization of microscopic defects)And disconnected. Therefore, the section of the part that fails due to stress corrosion cracking will contain the characteristic area of stress corrosion cracking and the 'dimple' area associated with the polymerization of micro-defects. Spot corrosion: spot corrosion refers to local corrosion with high degree of dispersion on the surface of metal materials, which is mostly non-corrosive or slightly corrosive. The size of common corrosion spots is less than 1. , The depth is often larger than the surface aperture, the lighter ones have shallower corrosion pits, and the more serious ones even form perforations.