Engineering MAterials.. Chemistry Essay Example | Topics and Well Written Essays - 750 words

Engineering MAterials.. Chemistry - Essay Example Q2. Yield strength corresponds to the load at which plastic deformation starts in a material while Ultimate tensile strength corresponds to the maximum possible loading below fracture. This means a component will not deform as long as the loading is below the yield strength of the material. Because plastic deformation of component is not permitted therefore design is based on yield strength. It should be noted that yield strength is always lower than ultimate tensile strength. Q3. Elastic modulus of a material depends on the nature of inter-atomic bonding in the material. If chemical composition changes, so does the nature of the inter-atomic bonding in the material. Let us take an example of low carbon steel or mild steel. In this case the inter-atomic bonding is predominantly Fe-Fe bond so it has elastic modulus that depends on the nature of Fe-Fe bond. Now let us take an example of SS316L. In this case the composition has changed considerably. Its composition is Fe-18Cr-12Ni-0.03C. Now this material has different kinds of bonds like Fe-Cr, Fe-Ni and Ni-Cr besides the Fe-Fe bonds and therefore, elastic modulus of this material is different from that of low carbon steel. Q4. This is because it is much easier to carry out hardness testing than carrying out tensile testing. One needs to prepare sample for tensile testing which is much more tedious than preparing a sample for hardness testing. At the same time one gets fairly good idea about strength of the material from hardness testing. As hardness is a measure of material’s resistance against deformation, therefore higher hardness implies higher strength. Q6. Fracture toughness is defined as K = ; where, ï  ³ is yield stress of the material and a is the critical flaw size. These two quantities are measurable. Besides, Kc = is a material property. The as long as K < Kc; the component is safe for use the moment K approaches Kc, the component becomes prone to catastrophic fracture and must be taken