So, why did it fail? If the failure is due to mechanical causes, including fracture, wear and deformation, a true answer is always “because the stress exceeded the strength.”

My favorite example is the story of why human-resource people decided that they should discourage people from “using knowledge in the workplace.” Huh? I really did not understand this idea at first.

Debbie Aliya's series on critical thinking continues.

In the last post (part 2), I discussed my definition of critical thinking. Critical thinking is only one skill set in the “took kit of thinking” that I have developed over the last 25 years. In order of our natural tendencies, I usually list the six basic thinking types as follows.

We talked about David Levy’s book Tools of Critical Thinking: Metathoughts for Psychology in part 1. There is no similar book for people involved in failure analysis, although that will change if I ever finish the book I have been working on since 2003.

After spending a few years on a LinkedIn Group called “Critical Thinking in the Workplace,” it became clear to me that there was no universally accepted definition of critical thinking. 

Every once in a while we have large, painful failures that are visible to lots of people.

NSL Analytical Services, an independent testing laboratory, has been acquired by May River Capital, a Chicago-based investment firm. NSL Analytical, which opened in 1945, serves over 1,700 customers globally from two locations in Warrensville Heights, Ohio. The company provides a range of analytical testing for quality control, failure analysis, product performance and material selection and characterization. These services include metallurgical evaluations and mechanical testing.

Technically, the cracks discussed in part 1 are quench cracks because they showed up after quenching.

Figures 1 and 2 show cylindrical parts that were apparently intact prior to hardening heat treatment (austenitize, quench and temper).