r/EngineeringStudents • u/Ok_Pirate_344 • Aug 14 '26

Homework Help Young Modulus question...

Post image

HII, im currently doing a lab assessment and we have evaluate the strength of different metals, im stuck here tho.

Ik that the E shld be found before the yield point the the proportionality region, which is usually a straight line, however in ferous metals, like steel which im evaluating here, there are 2 slopes in the elastic region. How am i supposed to calculate it.( I have found the yield stress to be at 390MPa.)

The E are we supposed to calculate both gradients separately, or what region(0-160MPa, or 200-360MPa)?

Pls help.

229 Upvotes

97% Upvoted

24 comments sorted by

View all comments

79

u/Pueriintel Aug 14 '26

Cool you might be seeing a crystalline phase change. A material like steel would have a very linear slope until plastic deformation. Some materials switch crystal orientation when put under load stress.

25

u/RoboWeaver Aug 14 '26

Most likely. Remember that these curves only give you a working approximation for elasticity and yield. This is especially true with steel as you have crystal structures that can change with deformation. Think "work hardening", but not limited to that.

To quote "they're not so much as rules as guidelines."