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September 05 2015


Failure Analysis Testing - Cause & Prevention

Mechanical analysis houston
Real cause failure analysis testing of metal products uses macroscopic and microscopic examination methods, and various investigative tools including nondestructive testing, mechanical testing and chemical analysis. The failure analysis investigation is focused on the metallurgical aspects of the failure. They typically do not emphasize factors including stress or load distributions. The steps followed, your order of the steps and also the failure analysis services performed during a failure investigation may vary depending on the type of failure being investigated.

Failure analysis houston
Collecting and Assembling History
The root cause failure analysis investigation should begin by obtaining background information on the failure. Including collecting available details about the manufacturing, processing, fabricating method, and repair history of the failed component. Processing and repair records, pertinent codes, specifications and related standards, as well as specifications, drawings, and style criteria should be included. Data should be provided about the materials, mechanical properties, heat treatment, as well as any surface preparation including cleaning, grinding, plating or painting. The service history ought to include the date, time, temperature, and environmental conditions of the component.

In addition to collecting the history information, photographs with the failed component and also the failure site should be taken. These photographs will document the venue and type of failure and will become part of the permanent record in the failure.

Nondestructive Testing
Nondestructive testing can be useful in failure investigations, particularly magnetic particle inspection for ferrous metals, liquid penetrant inspection, and ultrasonic inspection. These inspection methods are used to detect surface cracks and discontinuities. Radiography is used to examine components for internal discontinuities, for example voids and porosity.

Visual Examination
Until the investigator can examine the failed component, it needs to be isolated and protected from further damage. The component must be handled carefully and must be sheltered from the corrosive environment to preserve the failure.

The investigation should begin with a visual study of the failure site and part. All observations must be recorded or photographed and details must be gathered prior to part is cut for destructive testing. The visual examination includes inspection of the fracture faces and crack paths, with an assessment of abnormal conditions or abuse that this part endured during its service life.

Macroscopic Examination
Macroscopic examination is surely an extension of the visual examination and evaluates quality and homogeneity of the part. It is employed to determine the origin of the failure and the sort of fracture such as ductile, brittle, torsion or fatigue. Macrostructural features may be used to assess internal quality, presence of hydrogen flakes, chemical segregation, hard cases, flow lines and welds.

Mechanical Testing
The mechanical properties of an metal can be used to determine all the various usefulness and the service that could be expected from the material. Mechanical testing services measure the strength, ductility and other physical properties of materials under various conditions, such as temperature, tension, compression, impact and load.

Metallurgical Examination
Metallurgical examination is performed to determine microstructural features like inclusion content, grain size and rolling direction. Metallographic examination demands the use of high magnification microscopy. These examinations can sometimes include optical as well as scanning electron microscopy. Optical microscopic examination is used to determine grain size, microstructure and inclusion type and content. On the other hand, scanning electron microscopy is used to discover abnormalities, such as inclusions, segregation, and surface layers, in addition to fracture features and, with the aid of energy dispersive analysis, can identify inclusion type and corrodents around the fracture face. Microhardness exams are performed to measure case depths, evaluate cold work, determine weld quality and figure out mechanical properties of small parts.

Chemical Analysis
Inside a failure investigation, chemical analysis is completed routinely to ensure that the pad is what was specified. As well as obtaining the bulk composition of the material to confirm the grade used, it can be necessary to analyze surface contaminants. Chemical analysis is carried out on the base material along with corrosion products, deposits or coating layers.

Simulation Tests
It sometimes may be helpful to determine the reason for the failure by means of testing that simulates the physical conditions under which the failure occurred. The simulation may provide information as to the suitability of the material towards the environment and can also what is heat treatment or performance in the part in a controlled environment such as salt spray. Some types of simulation tests require accelerated testing in order to obtain information within a reasonable time. Interpretation of accelerated tests must be done with care because the limitations of the tests should be recognized.

Data Analysis, Conclusions and Report
As soon as the completion of the outlined steps, the investigator should be ready to interpret and summarize your data that has been collected. Many of the work performed may well not contribute in determining the foundation cause of the failure, yet it might be helpful in eliminating some possible causes. Mixed with, the steps that were outlined will, in most cases, enable the investigator to conclude the root cause of the failure. The failure analysis report usually supplies the following:

� Description with the failed component
� Conditions during failure
� Background service history
� Mechanical and metallurgical data about the failed part
� Evaluation in the material quality
� Discussion of mechanisms that designate the cause of the failure
� Strategies for prevention of future failures or action to be taken with the exact same parts

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