Cold Rolling Reduction Calculation Troubleshooting: Negative Signs Explanation

[mikex24]

I have some difficulties on calculating the reduction on cold rolling process but mi signs is negative. Is that normal? Cheers

 

[rock.freak667]

Your negative sign just means that the bar is reducing in size. Just put the values as positive.

For the second reading, if you took the already reduced bar and reduced it again, then your 'original' readings would be from the first set.

BUT if you took a new bar, and then reduced it, it would be the actual original readings.

 

[mikex24]

Thank you for the reply.. I use the same bar for all of the rollings. So my second equation to calculate the reduction will be like this one? ((5.25-5.83)/5.83)/100 ??

 

[rock.freak667]

Thank you for the reply.. I use the same bar for all of the rollings. So my second equation to calculate the reduction will be like this one? ((5.25-5.83)/5.83)/100 ??

That should be it, yes.

 

[mikex24]

Thank you very much for the help.

 

[mikex24]

I am trying to produce the graphs of the Hardness VS Reduction which i calculated and then to explain the effect of cold rolling on Hardness. I produce those graphs but seems something is wrong. The graphs which produced it is not linear and no curve and i can't make any explanation... Any help? Cheers

For example:
Hardness:
65.3
45.3
84.7
89.2
93.2

Reduction:
0
9.33
18.35
29.7
42.14

 

[rock.freak667]

It looks like on average, as your reduction of area increases, so does the hardness.

 

[mikex24]

Thanks :).. Can you explain me little more the effect of cold rolling on hardness of the metals ? How does cold rolling effect on the hardness of the materials...? Cheers