Failure analysis methods and procedures
1, The collection of background data and the selection of analytical samples
2，Preliminary inspection of failure parts (visual inspection and record)
3, Nondestructive testing
- 4, Mechanical properties testing5, The selection, identification, preservation and cleaning of all samples
6, Macroscopic inspection and analysis (fracture surface, two cracks and other surface phenomena)
7, Microscopic examination and analysis
8，Selection and preparation of metallographic section
9，Inspection and analysis of metallographic section
10, Determination of failure mechanism
11，Chemical analysis (large area, local, surface corrosion product, sediment or coating and trace sample analysis)
12，Analysis of fracture mechanism
13，Simulation test (special test)
14，Analyze all facts, draw conclusions, and write reports (including recommendations)
The above is the whole process of failure analysis, of course, to a certain failure parts, not necessarily all these processes, according to the complexity of the failure parts, specific analysis
The failure of the main part of the analysis report
1, the bad parts that
2, when the working condition of failure
3, the history of previous work
4, manufacturing and machining process
5, mechanical and metallurgical research failure
6, metallurgy quality evaluation
7, the failure mechanism of the summary
8, to prevent similar accidents
Questions to be answered in failure analysis
Is the order of fracture determined?
If the failure involves cracking or fracture, then the starting point is determined?
Does the crack originate from the surface or below the surface?
Is the crack related to the stress concentration source?
How long is the crack? How much is the load?
Loading type: static, cyclic or interrupted?
What is the fracture mechanism?
What’s the approximate temperature at break?
Is it caused by temperature? Is it caused by wear? Is it made of corrosion? What kind of corrosion is that?
Do you use the right materials? Is the material quality up to the standard?
Are the mechanical properties of the material up to the standard? Are the bad parts properly treated? Are the defective parts correctly made? Are the parts correctly installed? Are the parts repaired during use? Are the repairs correct?
Does the parts run properly and can the parts be modified to prevent similar accidents?
Is it possible that the same parts are being used at the same time? How can we prevent them?
Attention: to distinguish between the results obtained from facts and the presumed ones