1、 Definition and Analysis of Failure
Failure: Failure occurs when a component fails to achieve its intended function due to changes in size, shape, material organization, and performance. In the standards of the Ministry of Aviation, a failed component is defined as a malfunctioning component.
Failure analysis: A technical and management activity that comprehensively analyzes the macroscopic and microscopic characteristics, materials, processes, physical and chemical properties, specified functions, stress states, and environmental factors of failed components, identifies effective modes and causes, and proposes preventive and corrective measures.
2、 The purpose and significance of failure analysis
The purpose of failure analysis is to determine the object of failure analysis (the incident or the first failed component), determine the failure mode of the failed component, identify the cause of the failure, propose improvement or preventive measures to prevent similar accident components from happening again, and ensure the use of mechanical components.
The significance of failure analysis: Through failure analysis, it can reduce and prevent the recurrence of similar failure accidents in mechanical products, thereby improving the quality of mechanical products and reducing economic losses. It is a scientific way to continuously improve products and create brands. It can provide reliable technical basis for arbitration of liability for failure accidents, modification and formulation of product quality standards, etc. Failure analysis is the technical foundation of mechanical product maintenance work, and is a pioneer in technical development, transformation, progress, and even the improvement of the overall scientific and technological level.
Requirements for the user:
1. Provide the name, model, basic performance indicators, and purpose of the equipment;
2. Provide design drawings, materials, manufacturing, and heat treatment processes for the fractured parts of the equipment as much as possible;
3. Provide the usage status of the equipment, especially the detailed usage and maintenance status of the equipment during the period before its failure;
4. According to the requirements of on-site analysis and inspection, samples are taken from the equipment and properly stored.
The general steps of the failure analysis process are:
1. Understand and analyze the usage, structural characteristics, and stress characteristics of the equipment;
2. Observing and analyzing the macroscopic deformation and fracture characteristics of failed components;
3. Based on macroscopic analysis of the possible locations of fracture sources, select 3-5 locations for sampling;
4. Hardness measurement;
5. Acid immersion low magnification test;
6. Chemical composition analysis;
7. Stereomicroscope macroscopic fracture analysis;
8. Scanning electron microscopy micro fracture analysis;
10. Energy spectrum microanalysis;
11. Metallographic analysis.