lap 2+3 Report

 lab report #2. This report should cover both lab experiment/session 2 and 3 (Resistance Spot Welding and Microscopy/Sample Preparation). Therefore, the due date of lab report #2 is next week Monday (02/22) and Wednesday (02/24). The upload

link

will be available then for you to upload the lab reports. 

Lap2

Link

 

https://drive.google.com/file/d/1InNL3l7p3kVuERO4JabTRYcaR6cZXp5x/view?usp=sharing

Lap3

link

https://drive.google.com/file/d/1Zvxcq8XP1T9KCGCdVB1fjitRuR5ndzHr/view?usp=sharing

Link

MIME1650 Laboratory 2

Resistance Spot Welding (RSW) Test

Please keep your welded sample for future laboratories.

Objective
The student learns the basic knowledge about resistance spot welding and welds a

specimen for future laboratories.

Agenda
-Introduction to RSW Machine

-Laboratory 2 procedure

Equipment and tools
-Resistance Spot Welding Machine

-Micrometer -Steel Ruler

-Vernier Caliper -Marker (Scriber)

-Protective screen

Sample Low Carbon Steel Sheet

Lab Executants Individual

Lab Period 1 week

Report Individual

Location NE-1100 (Groups first meet TA’s in NE 1061)

Introduction
Resistance spot welding (RSW) is one of the most important joining techniques. It is a

very rapid and economical process, extremely well suited to automotive industry.

In RSW, both heat and pressure are used to affect coalescence. The heat is the

consequence of the electrical resistance if the work piece and the interface between them.

The pressure is varied throughout the weld cycle. A certain amount of pressure is applied

initially to hold the workpiece in contact and thereby control the electrical resistance at

the interface. When the proper temperature is attained, the pressure is increased to

facilitate coalescence. Usually the required temperature can be attained and coalescence

achieved in a few seconds or less.

The heat for RSW is obtained by passing a large electrical current through the

workspaces for a short period of time. The amount of heat can be determined by the basic

relationship:

RtIH
2

=

Where H is the total heat input, I is the current, R is the electrical resistance of the circuit,

and t is the length of time in which current is flowing. It is important to note that the

workpieces form part of the electrical circuit, and the total resistance between the

electrodes consists of three components:

1. The resistance of the workpieces
2. The contact resistance between the electrodes and the workpiece
3. The resistance between the surface to be joined, known as faying surface

Figure 1 Spot-Welding Machine

The objective of RSW is to simultaneously bring both of the faying surfaces to the proper

temperature while keeping the remaining material and the electrodes relatively cool. The

electrodes are usually water-cooled to keep their temperature low and to aid in keeping

them in proper condition.

As shown in Figure 2, the overlapping workpiece is positioned between water-cooled

electrodes, which have reduced areas at the tips to produce welds that are usually from

1/16 to ½ in. (1.5 to 13 mm) in diameter. After the electrodes are closed on the

workpiece, the controlled cycle of pressure and current is applied, producing a weld at the

metal interface. The electrodes then open and the workpiece is removed.

A satisfactory spot weld, such as the one shown in figure 3, consists of a nugget of

coalesced metal formed between the faying surfaces. Figure 4 shows the RSW’s squeeze,

weld, hold and off time.

There should be little indentation of the metal under the electrodes. The strength of the

welds should be such that, in a tensile or tear test, the weld will remain intact and failure

will occur in heated affected zone (HAZ) surrounding the nugget. If proper current

density and timing, electrode shape, electrode pressure, and surface conditions are

maintained, sound spot welds can be obtained with excellent consistency.

Figure 2 The Scheme of RSW

Figure 3 A Spot Weld

Experimental Procedure

1. Measure the coupon size (length, width and thickness) Data Sheet 1
2. Mark out the spot-weld location at 1′′ from each edge of the sheet coupon along

the line.

3. At the welding machine, check if the electrodes are fitted and aligned properly.
4. Switch on the red water supply valve located below the weld controller.
5. Connect Air hose to the machine.
6. Switch on the power knob on the Weld Control Unit (WCU).
7. On the door of WCU ensure that

• Schedule #7 is selected
• The red Control Stop knob is in released position.
• The ‘DAS’ knob is in “Bypass” mode
• The knob for welding must be on No Weld.

8. Wait till the Hand Held Terminal (HHT) initializes. It should show the display
record the previously made weld.

9. On the HHT, press ‘Program Mode’/‘F1’ (Review Schedule)/‘F2’ (to change
Schedule#)/‘07’ (to select Schedule #)/‘Enter’

10. Check the weld schedule parameters. The parameters are:
Current 10KA, Cycle 10, Electrode Force (lbs) 800

Electrode tip Diameter 5mm

11. To change the weld parameters:

• Take the cursor key on the HHT to select the function you want to modify.
• Enter the new values.
• Press ‘F3’ to download changes.
• Press ‘Enter’ twice to save changes to WCU#00, and Schedule #7.

12. Place the coupon at the point you want to weld and operate the machine in No
Weld.

13. Adjust the position of the coupon so as to get the weld at the correct location.
14. Turn the Weld/No Weld knob to Weld.
15. Set protective screen for safety.
16. Make welds (two welds on one coupon) at the marked locations. See if expulsion

occurs.

17. Go HHT, press “Display Mode/F1/Weld Data” and view and record the welding
data.

Figure 4 Schematic diagrams of RSW Stages

Data Sheet

1. Specimen Size Date:

1
st
Measure 2

nd
Measure 3

rd
Measure Average

Sheet 1 Length

Sheet 2

Sheet 1 Width

Sheet 2

Sheet 1 Thickness

Sheet 2

2. Welding Records

Squeeze. ………cycle; Hold….…..cycle

Current

Actual

Setting Max Min Average

Weld

Cycle

Electrode

Force

Expulsion

(Yes/No)

Comment

Weld#1

Weld #2

MIME1650 Laboratory 3

Microscopy and Sample Preparation

Objective

The student should learn to prepare the sample and to use microscopy to observe material

structures.

Agenda

• Laboratory 2 procedure (Team work)

• Use of microscopes and their nomenclature

• Methods of sample preparation

Procedures and Report Requirement

Read and follow the instruction when you start to work.

1. Cut sample.

1. Mount sample using pneumatic device.
2. Grind sample on coarse and fine grinding surfaces.
3. Polish sample.
4. Etch sample with natal.
5. Observe sample by using microscope. Sketch the microstructure as completely as

possible in your report.

6. Use a polarizing filter on the microscope and observe the grain structure.
7. After sketching the microstructure, measure the sample surface roughness (set

‘cutoff’ 0.010, V-Pilotor).

Sample preparation

(Do Not Forget: You MUST Wear Safety Glasses in Lab!!!)

The sample used in material science microscopy usually has to have a very flat surface. If

accurate structure is to be observed, care must be taken in preparing the surface to avoid

unwanted scratches, heat effects and other forms of

damage.

There are five major operations in the preparation of metallographic specimens:

Sectioning, mounting (optional), grinding, polishing and etching.

Sectioning

Sectioning, the removal of a conveniently sized, representative specimen from a

larger sample, is the most important step in preparing specimens for physical or

microscopic analysis. Incorrect preparation may alter the true microstructure and

lead to erroneous conclusions.

Sectioning methods usually include sawing (using hacksaws, band saws and wire

saws), abrasive cutting and electric discharge machining. In our lab we use a

consumable-wheel abrasive cutting machine. It is often performed using a

coolant, ensuring an almost plane surface without serious mechanical or thermal

damage.

Procedure

1. To cut a suitable size, mark your specimen.

2. Use handles to adjust the specimen’s position.

3. Fix specimen rigidly

4. Cover the lid.

5. Push cutting and bump button.

6. Pull handle down slowly and apply proper pressure.

7. Push STOP button to finish cutting.

8. Remove specimen and clean cutting machine.

9. Remove any burrs and clean the sample by washing it.

Mounting

Mounting is often necessary in the preparation of specimens for metallographic

study. Although bulk sample may not require mounting, small or oddly shaped

specimens should be mounted to facilitate handling during preparation and

examination.

Standard mounts usually measure 25 mm (1 inch), 32 mm (1.25 inch), or 38 mm

(1.5 inch) in diameter; mount thickness is often approximately one half the mount

diameter.

How to do?

1. If MOLD BASE is in the bottom of MOLD CYLINDER, rotate
RAM CONTROL to ‘UP’ position.

2. Position sample on MOLD BASE. For easy release, spray little
lubricant on MOLD BASE in advance.

3. Rotate RAM CONTROL handle to ‘DOWN’ position.

4. Add mounting material – BAKELITE POWDER about 1
spoonful.

5. Insert and lock CLOSURE.

6. Rotate RAM CONTROL to ‘UP’ position. Apply pressure to
4200 psi (left mounting machine: the red point in middle line.

Right one: to Red Point) because the mount size is 1.25 inch.

Don’t exceed the Red point.

7. Put HEATER into MOLD CYLINDER. Turn on.

8. Rotate TIMER to 8-10 minutes.

9. Turn off HEATER. Use cooling cylinders immersed in water

10. Rotate RAM CONTROL to ‘NEUTRAL’ position. Allow
pressure to indicate zero.

11. Loosen CLOSURE

12. Raise Handle to vertical position. Keep one hand on Handle.
Rotate RAM CONTROL to ‘UP’ position.

13. Remove CLOSURE and mounted specimen with heat-resistant
glove. Be careful, it may be ‘Hot’.

14. Immediately mark the sample for identification purposes.

Grinding

The purpose of grinding is to remove any surface damage caused by cutting and

coarse grinding.

1. Coarse grinding: Chamfer the edges of the sample to 45° to prevent
tearing of the lapping cloth. Grind the sample surface to remove any

polymer residue. Clean the surface.

2. Fine grinding:
• Start with grit 240 abrasive paper which flat working surface is

flooded with water.

• Hold sample face down and apply it proper pressure. Go
forward and backward against working surface of paper with

full strokes and without contacting with abrasive paper. Clean

it. Then rotate sample 90°, repeat until the last series of

scratches are removed (shown in Figure).

(This method is used for carbon steel)

1st 2nd 3rd

• Progressively fine grind with smaller grits, of 320, 400 and 600
size, washing the sample between each grinding.

Polishing

Use rotating wheels with a napless wet cloth. Put Al2O3 suspension on the polish

cloth. Turn on with Slow Speed. Be careful to hold sample. Polish the sample

progressively using finer polishing particles. (Each wheel will have on one size

polishing grit, either 0.3 or 0.05) After final polishing, wash the sample under

running water and use a cotton swab and alcohol to dry the sample (prefer to use

blower).

Etching

A polished sample frequently will not exhibit its microstructure, because light is

uniformly reflected. To further reveal the microstructure, the surface may need to

be etched. For ferrous sample, nital is commonly used. Nital is a nitric acid and

alcohol mixture, and is highly toxic and corrosive.

• Put Nital to the polished surface of sample using a cotton swap.
• Let Nital stay on surface about 30 – 40 seconds.
• Rinse off using running water.
• Use Methyl Alcohol (Methanol) to dry it.

Now the sample is ready for microscopy. Take care to protect the surface. Never touch

the surface or carry the sample in your pocket.

Surface Roughness ( µm )

Drawing of sample under microscope:

1

MIME 1650 MATERIALS SCIENCE & ENGINEERING
Spring 2020

Introduction to

Materials Science & Engineering – Laboratory

The laboratory portion of MIME 1650 Materials Science & Engineering seeks to give the
engineering student a hands-on appreciation of what Material Science is all about. In this
portion of the course the student should gain an understanding of material properties and these
properties are affected by different processes. The knowledge of these effects is valuable when
selecting a material for a part or design. For example, certain applications require a material
that will not buckle under stress; others require more strength while others require more
ductility. In addition to selecting the right material, engineers must make their design cost
effective.

There will be seven (7) laboratory exercises spread over the course of the semester. Each
student will be required to submit a lab report which will be due one week after the completion
of the lab unless otherwise specified. ALL reports must be typed. Failure to do so will result
in a rejected report. Details on what is expected from your report are in the Report
Requirements section. If there are any questions about a particular lab, please talk to your
Teaching Assistant (TA) about your concerns and they will provide the needed help. They can
often critique your report upon request. Do not hesitate in asking questions if something is
confusing to you as asking questions is an excellent way to learn.

2

Laboratory Report Requirements

Introduction

All engineers and scientists are required to write reports documenting their work. Each
organization establishes its own required format. Reports are used for a variety of purposes.
First and foremost, it is a historical document of what, when, why and how something was
done. A reader of the report should, by the report alone, be able to replicate the experiment. A
report is often used by management to determine whether or not a project is meeting
expectations. Decisions of where to allocate available resources (such as labor and capitol) are
often made based on the written report. Engineers and scientists that communicate well
through the written report are in demand by industry.

Report Style

The report must be clear, concise and complete. A well written report avoids engineering
jargon and specialized language. The writer must remember that the reader often does not have
the knowledge or background that the writer has. Ideas must be expressed in a logical flow and
in complete sentences. Furthermore, the report must be concise. What this means is that the
writer should favor simple sentences where possible. Long, flowery sentences with many
subordinate clauses and qualifications are not appropriate in an engineering report. On many
organizations, the pertinent ideas being reported on must be stated in one page, often called
“The Executive Summary.” Regardless of what the organization may require, shorter but
complete reports are desired over long reports. A complete report indicates the writer is
honestly reporting what happened and why. If a project or experiment failed, the writer should
clearly state this and then explain why. The report should be decisive.
The report is a historical document of what occurred. Therefore, the report should be written in
third person as well as in past tense. Proper English is required throughout the report. Slang
words are not understood from generation to generation and may be misinterpreted when a
report is read a decade or so after the writing of the report. Since the report is archival, the
report must be prepared using word processing software. Hand written reports are not
acceptable. Not only is this unprofessional, but it reflects poorly upon the writer.

Report Formatting and Presentation

The following formatting guidelines must be followed

• Report must be printed on 8 ½ inch x 11 inch (letter size) white paper.
• All pages of the report including raw data, appendices and sample calculations should

be numbered with the page number centered or right aligned in the bottom margin
(footer).

• Font size should not be smaller than 10 point Times New Roman.
• All sections headings should be in bold font.
• Report should use double or 1.5 line spacing.
• Reports must be stapled in the upper left corner before submission. Stapling of the

report is the author’s responsibility as a stapler will not be provided.

3

Report Structure

The following report structure is required for all laboratory reports submitted by students in
MIME 1650: Materials Science and Engineering – Laboratory. Lab reports will be graded out
of 100, with each section weighted as shown.

Title Page 5 points
Objective 5 points
Abstract 5 points
Introduction 10 points
Methodology 10 points
Procedure 10 points
Data 10 points
Results 15 points
Discussion and Conclusion 15 points
References 5 points
Appendices 10 points

Title Page
The title page will consist of the report title, the names of the author(s) of the report, the
laboratory section and the date of the experiment. This will be a single page cover sheet.

Objective
The objective of the Report should be stated in ONE sentence. Several examples are provided
below.
“The objective of this report is to describe the automations of the 280-OBI Stamping line at
Shiloh Industries.”
“The objective of this report is to report the measurements of the sample block taken during
Laboratory Exercise One.”
“The objective of this report is to investigate the heat treating of AISI 4340 steel.”

Abstract
The abstract should describe the entire report including significant results. The abstract should
not exceed 250 words in length. The Abstract should indicate to the reader what was
attempted, what was accomplished and what the results were.

Introduction
The report introduction should be one or two paragraphs which describe the background
material for the report and place the report in context (e.g. why this test is important and what
the results of this type of test are used for). It should be interesting to read and should
encourage the reader to read the remainder of the report. The material contained in the
introduction should be general in nature. The remainder of the report will provide specifics
where needed. The main purpose of the introduction is to prepare the reader for what follows
in the report.

4

Methodology
This section provides the reader with a general understanding of the type of experiment which
was performed and how it was conducted. The background theory for the experiment should
be succinctly discussed. If an analysis method will be used to process the data, it should be
described here. This section mostly discusses what method was used for the experiment and
the reason why that method is preferred. The length of this section will vary depending on the
experiment.

Procedure
This section describes exactly how the experiments were performed. If necessary, a sketch of
the test setup should be provided. Exact equipment (with serial numbers for the specific
equipment) used will be described. The order of tasks shall be presented so that any other
experimenter should be able to follow the procedure. Long, detailed procedures should be
placed in the Appendix and referenced here.

Data
This section will present the raw data values obtained using the procedure of the previous
section. Where the data is lengthy, the raw data is placed in an appendix and referenced here.
Actual data recording forms should be placed in the appendix. This section should begin with
text describing the data and referring to tables and graphs that contain the actual data values
when necessary. This section will consist of only values actually measured. No computations
are allowed on the data values. Computations made on data are presented in the next section.

Results
Results include observations based on the methodology, the procedure and the data. It may
consist of computations and presentation of the results in a tabular or graphical form. When the
computations involve a long string of computations, the sample computations should be placed
in an appendix and referenced in this section.

Graphs and Tables
The preparation of graphs, figures and tables require that they be clearly labeled and
professionally presented. In some cases, this may require that they be presented on a complete
page in landscape orientation (i.e. sideways to the normal vertical (portrait) direction). If this is
the case, they should be rotated such that the upper right hand corner of the graph, figure or
table corresponds to the upper left hand corner of the report. The top of the graph, figure or
table will be at the normal left hand margin of the report.

Graphs should be plotted using computer software such as Excel, Matlab, Mathcad, etc. Each
axis should be labeled with its variable, symbol and appropriate units. An appropriate scale
and gridlines should be used. The graph should be labeled with a suitable title. A legend
should describe the symbols, line styles on the graph, and units. Gridlines should be numbered
according to the scale used.

Tables should be treated similarly. Tables should be inserted in the text immediately after they
are referenced. Long tables should be placed in an Appendix. Tables should be numbered and

5

titled. Each column will be labeled with a short heading, including the units. Where tables run
over several pages, the table will have headings on each page. Columns of numbers should be
aligned by the decimal point. Columns should be boxed since free form tables are not allowed
in the report.

Discussion and Conclusion
In this section, the writer reports on the conclusions drawn from the experimental work.
Conclusions are the important finding determined from the experiment. All statements must be
supported by the data and the results. Actual values should be stated or referenced for support.
New information not reported on earlier can not be introduced in this section. Any judgments
made should pertain directly to the work. For example, a judgment: “The experiment
corresponded well to the theory since the data differed at most by 3% from the prediction” is a
valid statement to make in this section since it is directly supported by the work. However,
“The experiment corresponded well to the theory because the tools used were new” is not valid.
In many cases, the writer may feel that additional work needs to be performed on the subject
matter of the report. This may be included in a few short statements at the end of this section.

References
Any resource used as reference for the work should be documented here using standard
referencing techniques.

Appendices
This section should be separated from the main report by a single page with the word
“APPENDICES” centered on the page. Each separate appendix should be titled, and labeled by
a letter starting with A (e.g. Appendix A, Appendix B, etc.). Appendices usually consist of
materials which are lengthy in nature and would make the report difficult to read if included in
the main body of the report. Typical appendices are raw data, sample calculations and long,
intricate procedures.