2.Centerline porosity 3.Interdendritic shrinkage porosity 4. Interdendritic gas porosity 5.Surface/subsurface porosity 6.Inclusion related porosity For each of the above types of porosity, a)Describe the identifying/characteristic features (e.g.size,shape,and location in the casting); b)Define the casting variables or critical criteria which relate to the occurrence of that form of porosity; c)Give a specific example of a system (i.e.,alloy,mold system,casting conditions,etc.)in which that particular form of porosity is commonly observed. 30.Describe the corrosion processes that may occur on improperly prepared welds in austenitic stainless steels. 31.An fcc single crystal,when pulled in tension,yielded at=o,,was elongated in easy-glide for 10%strain,when stage II began.Stage IlI began at s=40%and fracture began at 45%strain at o=3.5o a)Sketch the stress-strain curves b)On the same diagram sketch curves you would expect very similar crystals to show when tested after the following treatments: b.1)Initially extended 5%in tension at room temperature and unloaded. b.2)Initially extended 30%at room temperature and unloaded b.3)Initially extended 41%at room temperature,unloaded and then annealed for one hour at 15'C below its melting point. 32.With respect to failure processes (a)Describe the following accurately (b)Five engineering circumstances where they occur,the specific circumstances under which they occur (c)Show characteristic metallographic cross sections (d)Show standard data plots and describe axis: (1)Ductile failure (2)Creep rupture (3)Corrosion fatigue (4)Stress corrosion (5)Hydrogen Blistering (6)Radiation embrittlement (7)Temper embrittlement 33.(a)During the vacuum treatment of molten steel in a magnesia crucible it is2. Centerline porosity 3. Interdendritic shrinkage porosity 4. Interdendritic gas porosity 5. Surface/subsurface porosity 6. Inclusion related porosity For each of the above types of porosity, a) Describe the identifying/characteristic features (e.g. size, shape, and location in the casting); b) Define the casting variables or critical criteria which relate to the occurrence of that form of porosity; c) Give a specific example of a system (i.e., alloy, mold system, casting conditions, etc.) in which that particular form of porosity is commonly observed. 30. Describe the corrosion processes that may occur on improperly prepared welds in austenitic stainless steels. 31. An fcc single crystal, when pulled in tension, yielded at σ = σ y , was elongated in easy-glide for 10% strain, when stageⅡ began. Stage Ⅲ began at ε =40% and fracture began at 45% strain at 3.5 . σ = σ y a) Sketch the stress-strain curves b) On the same diagram sketch curves you would expect very similar crystals to show when tested after the following treatments: b.1) Initially extended 5% in tension at room temperature and unloaded. b.2) Initially extended 30% at room temperature and unloaded b.3) Initially extended 41% at room temperature, unloaded and then annealed for one hour at 15℃ below its melting point. 32. With respect to failure processes (a) Describe the following accurately (b) Five engineering circumstances where they occur, the specific circumstances under which they occur (c) Show characteristic metallographic cross sections (d) Show standard data plots and describe axis: (1) Ductile failure (2) Creep rupture (3) Corrosion fatigue (4) Stress corrosion (5) Hydrogen Blistering (6) Radiation embrittlement (7) Temper embrittlement 33. (a) During the vacuum treatment of molten steel in a magnesia crucible it is