# materials of engineering laboratory

In the spring semester of 2002, Dr. Woldesenbet and I gave a hand-on laboratory course: Materials of Engineering Laboratory, to the junior undergraduate students at the Louisiana State University. In this Blog, I am also adding some state-of-the-art techniques for materials laboratory.

Class schedule:

Quizzes:

State-of-the-art techniques for materials laboratory

### experiment 1: Crystal Structure: X - Ray Diffraction

Objective:

The purpose of this experiment is to introduce students to the use of X-ray diffraction techniques for investigating various types of crystal structure encountered in metallic materials.

### experiment 2: Mechanical Testing- Impact & Hardness Testing

Objective

The main objective of this experiment is to introduce two important basic mechanical property tests; hardness (using Rockwell testing) and impact (using Charpy testing). Chauvenet’s Criterion will be applied to identify outliers and probability paper will be used to ascertain whether or not the repeated measure hardness data is normally distributed.

Directions for Charpy Impact Test
1. Raise the hammer to the starting position and lock the safety latch.
2. Set the pointer on extreme left.
3. Unlock the latch and release the pendulum.
4. Note the reading.
5. Set the pointer on extreme left again.
6. Raise the hammer to the starting position again and lock the safety latch.
7. Position the specimen at the base so that V-notch does not face the pendulum.
8. Unlock the latch and release the pendulum.
9. Note the reading again.
10. Deduct the previous reading from this one.

Precautions:
1. Do not forget to put the safety latch.
2. While releasing the pendulum, make sure not to stand near to it.
3. Make sure that the pointer is at the left before releasing the pendulum.
4. Be careful while stopping the pendulum.

Directions for Rockwell Hardness Test
1. Chose the scale and indenter according to the material type.
2. Set the tester anvil according to the specimen shape.
3. Hold the indenter tightly into the tester head.
4. Place sample to be tested upon anvil.
5. Turn on the tester.
6. Set the major load according to the scale chosen.
7. Set the hardness scale from the control panel.
8. Place the sample on the anvil.
9. Turn wheel to elevate work into contact with test point and continue turning and forcing against indenter till the sign on the screen shows “Set” which means that the minor load is applied.
10. Push “Start” on the panel.
11. Wait until hear a beep sound and see a blink of “OK” sign. Note the hardness reading along with the scale, e.g. HRC 35.
12. If the sample has cylindrical surface, add round correction according to the “Round Correction” table in the lab, which is based on the hardness reading and the diameter of convex cylindrical surface.
13. Turn wheel to lower the anvil and take off the sample.
14. Take off the indenter and put it back.
15. Turn off the tester when work is done.

Precautions:
1. Be careful while handling the indenter. Do not hit it with any surface.
2. If tests are conducted on a single part make sure that indentations are each be a minimum of 3 indentation diameters apart.
3. Check the “Minimum Thickness Requirement” in the lab to ensure that your sample is sufficient thick for the scale chosen.

### Indentation test

In this class, macro-indentation is used to measure the hardness.

Hardness is a measure of a material’s resistance to localized plastic deformation (e.g., a small dent or scratch). Hardness testing involves a small indenter being forced into the surface of the material being tested under controlled conditions of load and rate of application.

The depth or size of the resulting indentation is measured, which in turn is related to a hardness number; the softer the material, the larger and deeper the indentation, and the lower the hardness index number.

Can one use indentation to extract material elastoplastic properties directly from the measured force-displacement curves? Or simply, is it possible to obtain material stress-strain curves from the corresponding indentation load-displacement curves? The interesting discussion can be found in:

On the uniqueness of measuring elastoplasticproperties from indentation
http://imechanica.org/node/1222

### experiment 3: Mechanical Testing- Tensile Testing

Objective

The primary objective of this investigation is to conduct a standard tensile test for determining the stress-strain behavior of a material sample (mild steel or aluminum) and to analyze the results of the tensile test to find the mechanical/material properties of the sample.

### experiment 4: Precipitation Hardening of Aluminum Alloys

Objective

The objective of this investigation is to learn how and why certain alloys (primarily Aluminum alloys) can be strengthened by Precipitation Hardening heat treatment processes.

### experiment 5: Heat Treatment - Quenching & Tempering

Objectives

1) To investigate the conventional heat treatment procedures, such as quenching and annealing, used to alter the properties of steels. SAE 1040 steel standard Charpy type impact specimens will be used;

2) To study the effects of heat treatment on the microstructure and mechanical properties of steels; impact strength and hardness will be measured for heat treated specimens;

3) To quantitatively evaluate the hardenability, or depth of hardness, of a steel rod through application of the standard (ASTM A255) Jominy End-Quench Test.

### Experiment 6: Fatigue Testing

Objectives

- To demonstrate the use of the Instron servohydraulic testing machine for testing specimens subjected to cyclic (fatigue) loadings.

- To analytically approximate the fatigue damage accumulated in a part which is subjected to a known fatigue spectrum

### Experiment 7: Polymers

Objective

The primary objective of this study is to gain an understanding of the mechanical properties, and underlying atomic structures that cause the properties, for the three major classifications of polymers: thermoplastics, thermosets and elastomers.

An evaluation and understanding of stress relaxation in polymers, which is directly related to their creep behavior, will also be pursued.

### Experiment 8: Fiber Reinforced Composite Materials

Objective

To investigate the strength and stiffness characteristics of laminated composite materials as a function of fiber orientation.

### Experiment 9: Metallography Specimen Preparation and Examination

Objectives
1. To learn and to gain experience in the preparation of metallographic specimens.
2. To examine and analyze the microstructures of metals and metallic alloys.

### Experiment 10: Ceramics

Objective

The primary objective of this study is to gain an understanding of the mechanical properties, and underlying atomic structures that cause the properties, of ceramic materials through application of Modulus of Rupture tests.

Homework: Ceramics
http://imechanica.org/node/1164

### Experiment 11: Corrosion

Objective

The primary objective of this experiment is to introduce the students to the corrosion phenomena as occurs in engineering materials. Some commonly used techniques for measuring and preventing corrosion will be s udied. Accordingly, the following will be investigated:

1. Measurement of the electrode potentials of the metals/alloys.
2. Demonstration of the principles of the electroplating process.
3. Demonstration of the principles of electrolyses plating and passivation.
4. Corrosion prevention by cathodic protection.
5. Corrosion mitigation by the addition of inhibitors.

### thermo-mechanical treatment

Dear Henry Tan,

I am a structural engineer and doing some research on thermo-mechanical treatment. My material is stainless steel ( wire) which was submitted to cold rolling before and then being posed to an oven under a temperature of about 250-350 C and at the same time, the wire is stressed with some tension load, the purpose of this process is to release the residual stresses inside the material. But I have some doubt that if this process can change the material properties or material structures, phase combinations and so on. So, could you please give me any comments, suggests on this issues or direct me to any book or scientific paper that I can acquire more information.

Thank you very much

Hamanh

### need to know more about X-ray Diffraction

Perhaps Ronjton was the father of X-ray, I need to know more about X-ray Diffraction.

Anybody can share with me.

Thank you

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