Hydrogen Embrittlement – Part 3
Posted by Rob in Failure Analysis on 13. Dec, 2010 | 2 Comments
Hydrogen Embrittlement – Part 3 High Strength Steels Achilles Heel Susceptible Materials While some stainless steel grades are susceptible, high strength steels with tensile strengths and hardness above 130,000 psi and Rockwell C35, respectively, are the most prone to hydrogen embrittlement. Steels below these tensile and hardness levels are generally immune. Why? Increasing hardness, most [...]
Hydrogen Embrittlement – Part 2
Posted by Rob in Failure Analysis on 06. Dec, 2010 | 1 Comment
Hydrogen Embrittlement – Part 2 High Strength Steels Achilles Heel The Metallurgical Phenomenon Hydrogen atoms are the smallest of any element. So small, that they easily travel between iron atoms. The boundaries between crystals, or grains, which are the structure of metals, are gapping canyons in relative size to hydrogen atoms. Once absorbed, hydrogen atoms [...]
Hydrogen Embrittlement – Part 1
Posted by Rob in Failure Analysis on 29. Nov, 2010 | 0 Comments
Hydrogen Embrittlement – Part 1 High Strength Steels Achilles Heel The Phenomenon Sudden brittle fracture in high strength steels resulting from hydrogen embrittlement represents an extremely dangerous phenomenon to industry, particularly since it is usually the result of factors that occur during the manufacturing process. Hydrogen embrittlement reduces ductility, often to the point where metals [...]
Analyzing Material Fatigue
Posted by Rob in Failure Analysis on 04. May, 2010 | 2 Comments
A variety of analytical tools and techniques are used to identify fatigue fractures and their root cause. These include macroscopic examination, microstructural analysis, hardness testing, chemical analysis, microprobe chemical analysis and scanning electron microscopy (SEM). There are three stages in the life of a fatigue failure; 1. Initiation, 2. Crack Growth (propagation), and 3. Final [...]
The Service Environment
Posted by Rob in Failure Analysis on 04. May, 2010 | 0 Comments
Once a product leaves the factory you, the manufacturer, have lost control and all bets are off. Abuse and inadequate maintenance are leading sources of failure by fatigue, as well as other failure modes. Failure of components or assemblies “up stream” from your product may introduce higher loads than the product or component was designed [...]
Fatigue in the “Real World”
Posted by Rob in Failure Analysis on 27. Apr, 2010 | 0 Comments
In the “real world” fatigue usually – that’s usually, not always – initiates at a location that acts as a stress concentration, or focal point, to the stresses imposed on a component. Stress concentrations take a wide variety of forms. They include geometric features (such as holes, slots, corners and radii), rough areas of surface [...]
Fatigue and its Failure Analysis
Posted by Rob in Failure Analysis on 22. Apr, 2010 | 0 Comments
On May 11th, 1842 the first major railroad disaster in history set off a chain of events which led to the discovery of the phenomenon that we now know as fatigue failure. The Paris – Versailles Express, hurtling down the tracks at the then astounding speed of 50 miles per hour, exploded in flames when [...]
