Understanding how to perform a failure analysis and what to do with the data obtained is important for being able to quickly solve metal problems such as component failures or issues with manufacturing or supplier quality. In fact, metallurgical failure analysis is a critical part of operational excellence and continuous improvement.
Failure analysis case studies provide a way for people to learn how failure analysis concepts are applied to real-world decisions and problems. This article contains examples of failure analyses that we performed.
These failure analysis case studies demonstrate the analysis tools used, the data obtained, and how the data was used to determine the metallurgical reason for the failure. Based on the metallurgical reason for each failure it was then possible to identify the root cause of each problem.
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The video below explains about two failure analysis case studies.
The first case study is for a manufacturing quality problem. Orange peel was observed on bowls after they were deep-drawn from low-carbon steel sheet. Orange peel is a cosmetic defect that occurs on parts produced by cold forming metal metal stock (e.g. sheet, plate, and wire). It is called orange peel because the surface has the appearance of the surface of an orange. The photos below show the sides of bowls without and with orange peel. The problem resulted in significant scrap losses.
The second case study is for a water faucet that failed during use, resulting in $120,000 water damage to a building. The failure occurred because a metal nut fractured. The photo below shows the faucet and the fractured nut.
The video below discusses the details of the bowl orange peel and faucet failure analysis case studies.
This failure analysis case study is for a component that was cracking during its fabrication. The cracking rate was about 30%. The component was made of a stainless steel alloy similar to PH 13-8 Mo. The component was fabricated from wire stock.
The following fabrication processes were used to make the component:
The cracks initiated at the root of the slot when a mating part was inserted into the component.
Cracked samples were split open completely to allow the fracture surface to be examined with a scanning electron microscope. The analysis indicated that the fracture mode was dimple rupture, indicating that the metal was exposed to a stress that exceeded its tensile strength. However, there was no plastic deformation of the material around the crack, which indicated that the metal had very little ductility.
The heat treatment that was used resulted in a steel with high yield and tensile strength and poor fracture toughness. Using a higher heat treating temperature of 1000 or 1050 °F was recommended. This heat treatment resulted in overaging, with a slight reduction in strength, but almost double the fracture toughness. The reduction in strength was acceptable, so the recommendation was implemented, and the cracking no longer occurred.
The root cause of the cracking was related to the design decision to use the H900 aging heat treatment. That heat treatment resulted in a material that had poor fracture toughness.
More failure analysis case studies are used in our Metal Failure Analysis online course. The course teaches about the steps of a failure analysis, the analysis equipment used, and how the data is used to determine the root cause of fractures, corrosion failures, and manufacturing quality problems.
Also, see our YouTube Channel for videos on different topics of metallurgy and metallurgical engineering for product design, manufacturing, and failure analysis
ASM International has handbook and online resources that have many failure analysis case studies.
Finally, we offer metallurgy consulting to help with failure analysis of metal failures and manufacturing quality prblems. If you need help, let's talk for 15 minutes. Use this brief form to get started.
Michael Pfeifer, Ph.D., P.E. is President of Industrial Metallurgists and a metallurgical engineering consultant with more than 30 years of experience in product design, manufacturing, failure analysis, and metallurgy training. He helps clients worldwide solve design and manufacturing problems and is the author of Materials Enabled Designs.
