Homework 8-solutions

# Homework 8-solutions - MAT 33 Fall 2007 Due Homework#8...

• Notes
• nizhes
• 5
• 100% (2) 2 out of 2 people found this document helpful

This preview shows pages 1–2. Sign up to view the full content.

MAT 33 – Fall 2007 Homework #8 – Solutions Due: 11/05/07 1.) The yield stress for an iron that has an average grain diameter of 5 x 10 -2 mm is 135MPa. At a grain diameter of 8 x 10 -3 mm, the yield stress increases to 260MPa. At what grain diameter will the yield stress be 200MPa? The best way to solve this problem is to first establish two simultaneous expressions of the Hall- Petch equation, solve for σ o and k y , and finally determine the value of d when σ y = 200 MPa. The data pertaining to this problem may be tabulated as follows: σ y d (mm) d - 1/2 (mm) - 1/2 135 MPa 5 x 10 -2 4.47 260 MPa 8 x 10 -3 11.18 The two equations thus become 135 MPa = σ o + (4.47)k y 260 MPa = σ o + (11.18)k y Which yield the values, σ o = 51.7 MPa and k y = 18.63 MPa(mm) 1/2 . At a yield strength of 200 MPa 200 MPa = 51.7MPa + [18.63 MPa(mm) 1/2 ] d –1/2 or d - 1/2 = 7.96(mm) - 1/2 , which gives d = 1.57 x 10 -2 mm . 2). A copper rod 15mm in diameter is to be reduced to 8.2mm in diameter. Calculate the amount of cold work this rod will undergo and then, using the diagram below, estimate its new tensile strength, yield strength and ductility.

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

This is the end of the preview. Sign up to access the rest of the document.
• Fall '07
• keith
• Deformation, Tensile strength, grain diameter

{[ snackBarMessage ]}

### What students are saying

• 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.

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

• 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.

Dana University of Pennsylvania ‘17, Course Hero Intern

• 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.

Jill Tulane University ‘16, Course Hero Intern