Introduction to Materials Science

A: Principle: Thermal barriers limit heat transfer modes, not chemical diffusion. Here the glass-fiber sleeve still blocks radiant and conductive heat, even partially delaminated, and it reduces mechanical scuffing. It doesn't stop oxygen ingress, so oxidation-driven cracking proceeds. Option D traps engineers who equate 'sleeve present' with full mechanical protection, ignoring relative motion and fretting paths.

A: Principle: Austenitic stainless under tensile stress plus chlorides fails by SCC. The temperature and chloride presence push 304 into its known SCC regime, with cracks starting at stress concentrators like threads. Option C catches people who see vibration everywhere and miss that preload dominates the stress state here.

A: Principle: Young’s modulus equals stress divided by strain in the elastic range. 200 MPa divided by 0.001 strain gives 200,000 MPa, which is 200 GPa, matching structural steel expectations. Option B traps engineers who drop a zero when converting percent strain to decimal.

A: Principle: MMC modifiers allow bonus tolerance as size departs from MMC. With a larger hole, you gain positional tolerance equal to that size difference, assuming datums are met. Option A traps people who remember MMC as 'worst case' but invert its effect during inspection.