February 23, 2023
It refers to the phenomenon that the materials in the equipment lose their specified functions due to the effects of pressure, time, temperature, environmental media and operation errors. For example, at 11:38 a.m. on January 28, 1986, at the Kennedy Space Center in the United States, the space shuttle Challenger was carrying out its tenth launch, but 73 seconds later, after the liftoff altitude reached 16 kilometers, an accident occurred. The Challenger exploded and disintegrated. A large number of debris from the explosion fell into the Atlantic Ocean, killing seven astronauts. Less than half a year after the completion of the project with a cost of 600 million yuan, the main steel frame structure of the main venue (i.e. the racetrack) of the International Nadam Congress in Ejin Horo Banner, Ordos, Inner Mongolia collapsed before the end of 2021.
The failure of metal components is an important safety hazard in our life. It is called failure analysis to analyze and study the characteristics and laws of various forms of failure of equipment and its components in the process of use, and find out the main causes of failure and the measures to prevent failure.
The failure forms and causes of metal materials are closely related. The failure forms are the apparent characteristics of the failure process of materials, which can be observed in appropriate ways. The failure reason is the physical and chemical mechanism leading to the failure of components, which needs to be diagnosed and demonstrated through the investigation and research of the failure process and the macro and micro analysis of the failure parts
The failure modes of materials in various engineering applications mainly include fracture, corrosion, wear and deformation, among which fracture failure is the most dangerous.
Classification of failure forms
Elastic deformation failure: elastic deformation failure occurs when the recoverable elastic deformation of the material caused by stress or temperature is large enough to affect the normal functioning of the equipment.
Plastic deformation failure: plastic deformation failure occurs when the material under load produces irrecoverable plastic deformation that is large enough to affect the normal functioning of the equipment.
Ductile fracture failure: The fracture that causes significant macroscopic plastic deformation of the material before fracture is called ductile fracture failure.
Brittle fracture failure: The fracture of material without or with little macroscopic visible plastic deformation before fracture is called brittle fracture failure.
Fatigue fracture failure: The fracture of materials under alternating load after a certain period is called fatigue fracture failure.
Corrosion failure: corrosion refers to the physical or chemical reaction between the material surface and the service environment, which causes damage or deterioration of the material. The corrosion of the material makes it unable to play its normal function is called corrosion failure. There are many forms of corrosion, including uniform corrosion that evenly spreads over the material surface and local corrosion that only occurs locally. Local corrosion can be divided into spot corrosion, intergranular corrosion, crevice corrosion, stress corrosion cracking, corrosion fatigue, etc.
Wear failure: When the materials show mutual contact or the material surface contacts with the fluid and makes relative movement, the shape, size or quality of the material surface changes due to physical and chemical effects, which is called wear. The loss of component function caused by wear is called wear failure. There are many forms of wear, including adhesive wear, abrasive wear, impact wear, fretting wear, corrosion wear, fatigue wear, etc.
Knowing how the metal components failed can take remedial measures to save the loss.
Generally, for some metal components that fail, we will use special technology to analyze them and find the direct cause of their failure. Haida has specially developed a high-precision and reliable HD-R831 metallographic microscope for you.
Through metallographic observation and macroscopic organization incision of materials, it can provide strong evidence for material failure, to ensure that qualified materials are used on equipment, to ensure the quality of equipment and facilities, and to guarantee the product quality of enterprises!