3. IfI cool a 4340 steel from a starting temperature 730C quickly enough, I can

Question

3. IfI cool a 4340 steel from a starting temperature 730C quickly enough, I can form martensite and not the expected phases BCC Fe and Fe3C. What is the minimum heating rate I need to use to form 100% Ugarten site according to Figure 10.23 in Callister (figure below)? 800 1400 Eutectoid temperature 700 1200 600 1000 500 800 400 A+ B 50%. 600 300Mistart) M(50%) M190%) 200 400 100 200 103 Time (s) 10 10 105 10 Adapted from H. Boyer (Editor), Atlas of lsothermal Transformation and Cooling Transformation Diagrams, 1977, Reproduced by permission of ASM International, Materials Park, OH

Explanation / Answer

4.

as we can clearly see from the figure we can get 100% martensite only if we cool at 1500 c/sec or above.the logic is draw a line from any temp and keep checking that it should not intersect any other c curve so that 100% martensite is achieved on cooling.

5.

surface material tends to be much harder and fine-grained than the interior because the outside part tends to cool quickly than the interior parts.

Related Questions

Navigate

• Browse (All)
• Browse 3
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.