Chapter 6 - Lecture 11_1

Chapter 6 - Lecture 11_1 - t t Strain Rate vs Temperature...

Info icon This preview shows pages 1–15. Sign up to view the full content.

View Full Document Right Arrow Icon
Chapter 6 Mechanical Behavior Issues to address… Hardness Creep Steady-state creep rate
Image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Hardness Figure 6-28
Image of page 2
Table 6.9 Common Types of Hardness-Test Geometries
Image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Hardness vs Strength Figure 6-29
Image of page 4
Vickers Hardness Testing
Image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
The simple expressions for Rockwell hardness numbers involve indentation, t, expressed in millimeters. A given steel with a BHN of 235 is also measured by Rockwell hardness tester. Using a 1/16 –in.- diameter steel sphere and a load of 100kg, the indentation t is found to be 0.062 mm. What is the Rockwell hardness number? Example
Image of page 6
Stress-Strain at Room Temperature Figure 6-30 ε σ E =
Image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Creep Test Figure 6-31
Image of page 8
Stress-Strain at “High” Temperature - Creep Figure 6-32 Creep occurs if T is > 1/3 to ½ times the melting point on an absolute temp scale (e.g., A36 steel, T melting ~ 1500 o C (1773K)). T Operating ~591 - 886K (318 - 613 o C)
Image of page 9

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Figure 6-33 Dislocation Climb
Image of page 10
Figure 6-34 time-to-creep rupture time-to-creep rupture
Image of page 11

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 12
Image of page 13

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 14
Image of page 15
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: t t Strain Rate vs Temperature Figure 6-35 RT Q Ce /-= ε . T R Q C 1 ln ln ×-= In a laboratory creep experiment at 1000C. A steady-state creep rate of 5×10-1 % per hour is obtained in a metal alloy. The creep mechanism for this alloy is known to be dislocation climb with an activation energy of 200 kJ/mol. Predict the creep rate at a service temperature of 600 C Example The relaxation time for a rubber band at 25C is 60 days. (a)If it is stressed to 2MPa initially, how many days will be required before the stress relaxes to 1 MPa (b) If the activation energy for the relaxation process is 30 kJ/mol, what is the relaxation time at 35C? Example The stress on a rubber disk is seen to relax from 0.75 to 0.5 MPa in 100 days. (a)What is the relaxation time for this material? (b) What will be the stress on the disk after 200 days? Practice...
View Full Document

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern