Introduction:
The material science and technology class at Central High School will complete a lab using metallography microscopes to examine weld specimens prepared by the local vocational school. Students will use the proper process to procure, mount, polish, and examine a metal sample. This lab activity will provide visual evidence of the effects of heat on grain structure.
Goals and Related Objectives:
The goals and related objectives are as follows:
Goal I. The student will learn the proper way to mount, grind, and polish samples for the microscope.
Obj. A. Given the proper equipment in lab, TLW properly orient and mount a specimen using the cool mounting process.
Obj.B. Given the proper equipment in lab, TLW utilize proper techniques to grind and polish samples to view under the microscope.
Goal II. The students will learn to use metallography microscopes
Obj. A. In lab, TLW will correctly identify the parts of a microscope.
Goal III. Students will visually identify changes in microstructure as a result of the welding process.
Obj. A. With a properly prepared sample, TLW identify pearlite and ferrite structures
Procedure
1. The specimen will be a cross-section of steel with a weld bead in the middle. Samples will be prepared in the welding shop at the vocational school. The samples will be cut to 1.5 in length with the weld bead centered.
2. After examining the sample, the student will do any final grinding on the sample to prep it for the mounting step.
3. Utilizing the cold mounting procedure, the student will mount the sample in epoxy resin.
4. After completing the mounting process, students will bevel the top and bottom edges of the epoxy.
5. Students now begin the polishing phase by using smaller and smaller grit abrasive until the final polishing is complete.
6. Now the students will etch the samples with 5% nitric acid solution
7. After etching, the students will observe their samples under the microscope, comparing grain size and distance from the weld site.
Timeline:
This will be a lab that will be done as a part of the unit on metals.
Course Rationale:
Material Science and Technology at Wartburg Central High School draws heavily from two workshops I have attended over the last four years. Our course is a hybrid between a manufacturing course and a materials course. While the subject matter is derived from the world of material science, manufacturing processes are also included and project work is sometimes set up to model the manufacturing environment. This combination best fits the need for our students in Morgan County. Our goals for the class are as follows:
I. Students will understand the uses of materials in the manufacturing process.
II . Students will understand the manufacturing process from design to mass production.
III. Students will understand and utilize material properties when completing projects
IV. Students will learn to communicate effectively and make observations of the world around them and share these ideas through journal writing.
V. Students will receive exposure to the manufacturing world as well as the post high school educational opportunities through guest speakers and field trips.
VI. Students will develop the habits of successful people to include time management, effective communication skills, being part of a team, and a commitment to high quality of work.
Word 97 doc file of this project: shoemaker.doc
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