The Stress Strain Curve - Essay Example

From the equation 2-5   G= E/ [2+V] = (114GPa)/ [2/ (1+0.33)]

                                                G= 42.9 GPa

14. A material with a hardness of HB 750 is classified as extremely hard, which is a feature

        of the hardest steels when the condition is surface hardened. Annealed steels have        

        hardness values that range from HB 120 to HB 230.

22. High carbon – 0.5% to 0.95%

         Medium carbon- 0.30% to 0.505

         Low –carbon- It is less than 0.3%

24. To improve machinability, lead is incorporated into the AISI 12L.
25. In most instances, when a material has good ductility and high hardness, it is deemed suitable for tools and parts of the machine that are about impact loads. A material with a hardness of HRC 40 equals around HB 375, which is considered moderately hard. Even though this level of hardness is considered suitable, a hardness value of HRC 50 or HB 475 is better when the ductility level is also high which represents about 15% elongation. Appendix 3, reveals forms of AISI 1040 and others that are non-listed and oil quenched, and they are listed as having adequate hardness levels. Appendix 4-1 indicates the same material that is tempered and quenched in water. The AISI 1040 WQT 700 possesses a hardness of HRC 43 (HB 401), a yield point of 92ksi, and an elongation percentage of 20.
26. To obtain a suitable hardened condition, the whole part is heated and then quenched. The part is hardened the entire time but differs in thick sections. However, no chemical constituent changes are experienced. During the carburizing process, the chemical structure of the surface is altered through carbon infusion. Therefore, the process of carburizing makes the outer surface harder while the inner surface becomes softer.