The Failure Analysis Process

Thursday, August 27, 2015

Previously, on our blog, we discussed the importance of failure analysis and gave a brief overview of the process. But today we are digging deeper into the analysis process and the testing techniques that are used along the way.

Background Information
First and foremost we must collect background information on the failure. This includes but is not limited to information about the manufacturing process, fabrication method, service history and how the failure occurred. Data such as material used, mechanical properties, heat treatment and surface prep should be provided. In addition to the data, photographs and/or a physical sample of the failure site should be provided.

Visual Examination
Once the sample arrives our Materials Scientist will inspect the failure visually and record information about fracture surface. A photograph will also be taken prior to additional testing. Once the visual examination is complete, the sample will be sent to our machine shop to be prepared for destructive testing.

Destructive Testing
Once the specimen has been properly prepared it will undergo a multitude of destructive tests.
  • Macroscopic Examination: This examination evaluates the quality of the part and is used to determine the type of fracture and origin of the failure. 
  • Mechanical Property Testing: Mechanical property testing includes hardness, tensile testing and Charpy impact testing. These tests help to determine the strength and ductility of the material at hand.
  • Metallography: During metallographic examination our Materials Scientist examines the specimen under intense magnification. Optical microscopy is used to determine grain size, microstructure and inclusion type. Whereas, our scanning electron microscope is used to determine abnormalities, such as fracture features and surface layers. Microhardness is also done to determine weld quality, case depth, mechanical properties of small parts, etc.
  • Chemical Analysis: Chemical analysis is performed to ensure that the material matches the given specifications. It is also used to determine the presence of surface contaminants.
  •  Simulation Testing: Sometimes it is helpful to test a specimen by means of simulation. Here we simulate the conditions under which the failure occurred. One of the most common simulation tests is done is our salt fog machine. Here we simulate the natural environment in a controlled salt spray chamber to test the sustainability of a specimen under environmental conditions.
Analysis & Reports: Upon conclusion of testing our Materials Scientist will interpret and summarize the data including detailed photographs of the testing procedures.

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