1. Watch the following videos and answer the questions below: a. Metallography P
ID: 1766804 • Letter: 1
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1. Watch the following videos and answer the questions below: a. Metallography Part I-Macroscopic Techniques https://www.youtube.com/watch?v=fc8ZTgYJCJw b. Metallography Part II - Microscopic Techniques i, what is the difference between macroscopic and microscopic metallography? i. Discuss the steps involved in polishing a sample for microscopic examination. ii. What does it mean to "etch" a sample? 2. 3. 4. Review the microstructure of each carbon steel sample listed below, label each micrograph (phases/structural constituents). List the primary alloying elements found in AISI 4140 alloy steel and provide examples of where this type of steel is used. Discuss the benefits, specifically as they relate to material properties, of alloying a steel. Calculate the relative amount of each structural constituent and phase based on the iron-carbon phase diagram. 5.Explanation / Answer
1. i): Difference Between Macroscopic and Microscopic Metallography:
Macroscopic Metallogrphy is nothing but observation of Crystal growth in a metal; mechanical, chemical and crystalline hetrogeneity. This is normally done by naked eye or low magnification ranges.
Microscopic Metallography is the close observation of a sample for size of graines; distribution of different phases in it; and estimation of amount of distributed phases. This is normally done at high magnification ranges.
1. ii): Steps involved in the Polishing sample in microscopic examination:
* Selection of specimen which we want to examine
* Held the specimen on rotating disc of polishing machine with mild pressure.
* Operate the machine which inturn polishes the specimen for scratches on the surface of the specimen.
1. iii.): Etching of Sample:
Etching is the process of revealing the internal microstructural details of a specimen for understanding grain size, shape and amount of various distributed phases in it.
There diffrent types of etching such as chemical etching, electrolytic etching; etc.
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