Title: Untitled Document
Course: Materials of Engineering

MET 2200 Laboratory
Cold Rolling and Tensile Testing

INTRODUCTION:

Cold working of metals changes the mechanical properties with respect to yield strength, tensile strength, ductility, and hardness.  The reaction to cold working can vary from alloy type to alloy type.  It will be the objective of this experiment to cold roll a plain carbon steel, an aluminum alloy and a copper alloy and determine the resulting changes in mechanical properties.  Text references: Chapter 6, sections 6.1 – 6.4 and Chapter 8, page 331.

PROCEDURE:

Each sample will be marked with a unique sample number and then will be measured to determine its initial cross sectional area, length, and Rockwell hardness.  Reference samples designated “as-received” will be kept for comparison purposes.  Samples designated “fully rolled” will then be cold rolled the maximum number of rolling mill passes as determined by visual appearance of the sample.  Another sample designated “half rolled” for each material will then be cold rolled to approximately half of the rolling mill passes of that previously observed amount for maximum amount of cold rolling.  The rolled samples will then again be measured for cross sectional area and length in order to determine the amount of cold reduction which has occurred.  The Rockwell hardness will be measured on the cold rolled samples.  Since most of the samples will be too large to pull directly in the Instron machine, tensile test samples will be prepared to obtain a cross section which can be tested.  All sample materials from this experiment will be retained for later metallographic examination.  Although the Instron captures a large amount of data, the test will be monitored by the lab teams in order to experience manual data collection during a tensile test.  Equipment manufacturers and models are to be collected for the report.  An individually prepared laboratory report is to be submitted by each student in accordance with the Laboratory Report Format.

DATA ANALYSIS:

Note any observed variations in test procedure and/or data collection which could have affected the results of the experiment.  A data table is to be set up for capture of all raw data.  This data is to be processed for engineering stress vs. strain to contain yield strength, ultimate tensile stress, fracture stress, per cent elongation.  Formulas used to process raw data are to be shown.  Rockwell hardnesses are to be converted to Brinell hardness.  Per cent cold work is to be calculated for each sample.  Appropriate handbook values are to be included in the data tables for comparison purposes.  Graphs are to be used for comparing tensile test results as a function of cold work and for comparing Brinell hardnesses as a function of cold work for each material type.

DISCUSSION:

The following are required discussion points.    Discuss the relationship of amount of cold working on the tensile properties and on the Brinell hardness of each material tested.  How did observed hardnesses relate to observed tensile test results?  Discuss how these results compared with handbook data.  Discuss how the deformation mechanisms caused the changes in mechanical properties which were observed as the materials were cold worked.

CONCLUSIONS:

Present conclusions for this experiment as supported by your data analysis and discussion sections.