Is this the cause of residual stress?

In summary, a task was given to a group of students to give a short presentation on different topics. One student, Andrew, is struggling to understand the relationship between residual stress and the observation that copper wire bends smoothly while mild-steel wire kinks and deforms. After researching and consulting his textbook, he asks for clarification from his classmates. One classmate suggests looking at the crystal structures and slip systems of the two materials, while another directs him to review the stress-strain curve for mild steel and copper. Additional references are also provided for further understanding.
  • #1
drew1.0beta
1
0
hi everyone..
my lecturer gave each of us a task..we have to give a short presentation next week. everyone have a different topic..mine is this:

"Explain the observation that a copper wire will bend smoothly around a finger, whereas a mild-steel wire will kink and deform to a polygonal shape"

Is these the cause of residual stress? i read from my textbook and search the internet to understand better...but i couldn't put 'residual stress' and wires together..can anyone explain to me?

THANKS ALOT!
-andrew-
 
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  • #2
This doesn't sound like residual stress to me. Consider that copper has an FCC crystal structure and steel generally has a BCC crystal structure. Do these structures have different slip systems?
 
  • #3
drew1.0beta said:
hi everyone..
my lecturer gave each of us a task..we have to give a short presentation next week. everyone have a different topic..mine is this:

"Explain the observation that a copper wire will bend smoothly around a finger, whereas a mild-steel wire will kink and deform to a polygonal shape"

Is these the cause of residual stress? i read from my textbook and search the internet to understand better...but i couldn't put 'residual stress' and wires together..can anyone explain to me?

THANKS ALOT!
-andrew-
Please review the stress-strain curve/diagram for mild steel and copper. Pay close attention to what happens when the materials depart from strictly elastic behavior. What is the significance of the increasing strain at constant stress for the mild steel?

One reference -
http://www.optics.arizona.edu/optomech/references/OPTI_222/OPTI_222_W4.pdf
http://www.phy.hr/~atonejc/mehanickaSvojstva.pdf [Broken]
 
Last edited by a moderator:

What is residual stress?

Residual stress is a type of internal stress that remains in a material even after all external forces are removed. It is caused by factors such as non-uniform cooling, plastic deformation, and material composition.

What are the common causes of residual stress?

The most common causes of residual stress include welding, casting, heat treatment, and mechanical deformation. Other factors such as material properties and environmental conditions can also contribute to residual stress.

How does residual stress affect materials?

Residual stress can have both positive and negative effects on materials. It can improve the strength and durability of a material, but it can also lead to distortion, cracking, and reduced fatigue life. The effects of residual stress depend on the type and magnitude of the stress, as well as the properties of the material.

How do scientists measure residual stress?

There are several techniques for measuring residual stress, including X-ray diffraction, neutron diffraction, and hole-drilling methods. These methods analyze the changes in material properties caused by residual stress and can provide quantitative measurements.

Can residual stress be eliminated?

In most cases, it is not possible to completely eliminate residual stress. However, it can be reduced through techniques such as annealing, shot peening, and stress relieving. It is important for scientists and engineers to consider residual stress in the design and manufacturing process to minimize its negative effects on materials.

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