Failure analysis

KEMA's failure analysis services help manage and resolve material and product failure problems

Failure analysis determines the failure mechanism and direct cause of failure. Failure analyses is an important function in all engineering disciplines. The materials engineer often plays a lead role in the analysis of failures, whether a component or product fails in service or in manufacturing.

In any case, one must determine the cause of failure in order to prevent future recurrence, and/or to improve the performance of the device, component or structure. KEMA helps manage and resolve material and product failure problems. We work to determine the cause of a failure and provide the customer with insight for solving the problem. Recommendations for improvement can also be provided upon request.

Circumstances
Failure mechanism categories related to metallic structures can be (amongst others):
> Fatigue 
> Cracking 
> Corrosion 
> Embrittlement 
> Fracture 
> Friction 
> Wear

There are several resources we can apply in order to determine a failure mechanism. The major steps in conducting a failure analysis are listed. Every case requires its own specific path of investigation. This depends on the outcome of previous steps and of what the next step is going to be.

Background information
The first step in conducting any failure analysis is to gain a good understanding of the conditions under which the part was operating. Our investigators enquire from those who work with the failed installation or component, as well as those who maintain it and visit the site whenever possible. Background information can also lead to an enquiry about manufacturing and design, of the failed installation or component.

On-site inspection
Visually inspecting the external condition of the failed component often provides valuable information for determining the subsequent analyses. First the failed component being checked for any differences from possible intact reference units. The circumstances of the failure must be investigated by checking for example:
1. Lot verification
2. Location and time of discovery of failure
3. Production records e.g. history files
4. Conditions of use and operating environment
5. Visual inspection

Based on the visual inspection and the background information a plan of action is defined, which is the series of steps that will be needed to successfully complete the case. As every case requires their own specific path of investigation each step`s outcome defines what the next step is going to be.

Macroscopic examination
Macroscopic examination is done to investigate typically features of a failed component which can be seen with a magnification of under 25x. Usually, pictures are taken from the failed part or component in the field. The items which are determined to hold valuable information are then examined closer by the use of high resolution camera's and stereo microscopy. This information can be used in fractography and for determining further investigation steps if needed.

Chemical analysis
Chemical analysis can be used in order to verify the materials origin. This can be both foreign as domestic. Chemical analysis is done on the bulk of the material or on deposits or scales to determine the chemical composition. In many cases, the Scanning Electron Microscope equipped with both EDS and WDS detectors can be a powerful tool for fast identification of surface materials. We also employ other techniques to determine chemical compositions like: 
> X-Ray Microanalysis 
> Spectrometry 
> Spark or arc spectroscopy 
> X-Ray Fluorescence (XRF, X-Ray Emission) Spectroscopy 
> Optical Emission Spectroscopy 
> KEMPhase

Metallography
Metallographic examination involves the sectioning of samples to examine the microstructure. The sections that are selected for examination are dependent on the type of piece and the mode of fracture. Sections from the sample should be taken in different planes so that any differences in the microstructure can be seen.

Mechanical Testing
Mechanical testing is done to verify the mechanical properties of the material. There are many types of mechanical testing that can be performed. The most common method is hardness testing: relative simple, low cost, and fast processing.

Mechanical Tests: 
> Tensile Testing 
> Impact Test 
> Bend Test 
> Compression 
> Flaring / Flattening 
> Hardness Testing 
> Nick Break 
> Drop Weight 
> Proof Load 
> Creep resistance 
> Fatigue resistance