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Name: Jenny
Status: Student
Age: 19
Location: N/A
Country: N/A
Date: N/A


Question:
What happens to samples of steels after: -

1)Annealing,
2)Quenching, and
3)Tempering?

Also, do you have information on modifying caeramics and composites? (i.e. chemical toughening of glass, changing components for composites) I would be grateful for any information on this subject matter. Thank-you for your time.

Looking forward to hearing from you soon.



Replies:
A simple response to your first complicated question is that doing the processing techniques you mentioned to steel changes the microstructure of the steel. Changing the microstructure of steel changes the properties of steel (such as hardness, strength, brittleness, etc.) There is no one answer for doing what you mention because there are multiple answers to multiple processing techniques.

For example, quenching steel in water will give different properties than that of steel quenched in oil. Annealing a sample at a high temperature for 1 hour will result in different properties than that of a steel annealed at a high temperature for 30 hours. Another factor is what kind of steel you are talking about. There are a multitude of steels out there with different compositions of iron, carbon, chromium, magnesium, etc. Processing them differently results in different properties. Now can you see why I said a simple answer to a complicated problem. Luckily, the properties of steels have been studied for a long time and there are lots of books out there on the subject. Try to find some books on introductions into material science for a good overview of the subject. If you have access to an engineering library at a local college, you will find reference books on the properties of metals and techniques on processing materials.

A simple response to your second complicated question is along the sample lines as the first question: it depends on how you process it. Ceramics can be made by different techniques such as uniaxial hot pressing, cold isostatic pressing, etc. You can sinter (i.e. densify) a ceramic under different temperature and environments for variable times to get different properties. A composite offers a different problem because you are usually using two different materials to make one material. That is, a composite made of silicon nitride matrix with silicon carbide fibers will be different in properties to a silicon nitride matrix with boron nitride fibers. Another condition would be how you orient the fibers in relation to one another in a matrix. I could arrange them as so

Obviously, depending how I tried to "stretch" theses composites would depend on how my fibers were oriented to the "stretching" direction. Processing techniques such as annealing and tempering can be done to ceramics as well, but due to the brittle nature of ceramics, these techniques are different than those done to steel. Once again, I urge you to seek out an into to materials science book to get a broad overview of these questions. I hope this helped because I know I did not answer your question in detail. Instead I gave a quick, simple explanation to a set of very good, yet complicated questions.

C. Murphy



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