Cold Rolling of Metals

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  • Topic: Metalworking, Work hardening, Hardness
  • Pages : 13 (3528 words )
  • Download(s) : 81
  • Published : April 14, 2012
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Abstract
This report is to highlight the methods, results and theory relevant during an engineering experiment called “cold rolling of metals". The purpose of this report is to show how readings obtained from the set-out experiment, can be evaluated to determine the behavior of 3 selected materials; Brass, Copper and Aluminium through the process of cold rolling. The form of the materials are in small strips which are processed via cold-rolling method 4 times from their original state to evaluate the effects incurred on hardness values, width, length and thicknesses. Hardness values/vickers numbers are determined for each material using a Vickers hardness tester and the measurements of width, length & thickness taken using a vernier caliper & micrometer. These values for each material are recorded pre-cold rolling from original and on each pass allowing the recorded results to be compared upon completion. On each pass a 3rd of a turn was applied to the rollers reducing the size of each material work piece in the order of Brass, Copper and Aluminium. Upon completion of this simple experiment the results were tabulated and a graph plotted to portray the collected data. It can be determined that the major affect exhibited by the process of cold rolling on each material was a clear increase in thickness reduction, width, length including an increase in hardness of each material. Copper appeared to be the most affected by the process, followed by Brass whereas Aluminium exhibited a small increase in its overall hardness to percentage deformation ratio. Certain recorded figures upon final analysis obtained during the experiment appear to be inaccurate in line with result patterns; and could be a result of numerous conditions one of which is the room for human error.

Nomenclature
oTo calculate the reduction thickness percentage on each pass the following formula is to be used which after measurements of thickness, length and width are recorded of each specimen. The units for Thickness are in mm to give the final reduction value as a percentage.

Table of contents
1Introduction/Theory5
2Aims & Objectives8
3Report Body9
3.1Health & Safety9
3.2Experimental set-up & procedure10
3.3Calculation & Results12
3.4Analysis & Calculations13
4Discussion/conclusion14
5References17

1Introduction/Theory

Background Theory

This report is to cover an experiment related to the process of cold-rolling. Cold rolling/working is a metal working process which is used to reduce the size & thickness of a metal. This process is used whilst the metal worked is cold, which differs from similar processes such as hot rolling, or bending operations that process the metal whist it is hot. Typically a process such as cold rolling is used to not only decrease the size of a metal worked but to also increase its overall strength & hardness properties.

There are various forms of cold working which can be used such as forging, stamping or rolling which all act to change the working material shape permanently – this can be defined as deformation. Deformation of a material occurs by defects also known as “dislocations” in the materials grain structure which move through the crystal structure. These dislocations in the grain structure impact a metal medium by changing its shape, and if viewed under a microscope it could be seen that each grain has a large number of dislocations. See Fig: [1] sourced from www.google/com/images/coldworking for further expansion.

Fig: [1]

Continued…
Cold working under normal conditions is used to plastically deform a material below its re-crystallization temperature, this is typically conducted under room temperature an example of this could be; a metal sheet or...
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