Engineering Materials - Material Manufacturing Processes - Two Modules

A: The cracking starts mid-face and at the root, with no heat discoloration or surface distress. A density gradient in PM gears does that quietly; the core never shares load the way the model assumes. Lubricant starvation explains pitting and scuffing first, which you don't see. Carburizing errors tend to show surface-linked issues or dimensional drift before mid-life cracking. Shot peening mistakes usually leave a flank pattern and are surface-driven, not rooted in the bulk where this one started.

A: MAWP sign-off lives and dies on traceability and proof test evidence. Without confirming the vessel itself is what the drawing claims, every downstream check is theater. Loop checks matter, but they don't make an uncertified shell safe. PSV setting without nameplate confirmation risks testing the wrong device. Weld appearance can look perfect while the chemistry or heat treatment is wrong, which auditors won't forgive.

A: Forging aligns grain flow with load paths and gives predictable fatigue life where the model is most sensitive. Gravity die casting feels tempting because it's cheaper and cleaner than sand, but porosity control is still a gamble for bearing fits. Vacuum-assisted HPDC improves surface quality, yet trapped gas and thin sections fight fatigue margins. Sand casting can survive static loads, but the GD&T stack-up and section thickness push mass and variability the wrong way.

A: A PSV assumes the event fits its sizing basis. Runaway kinetics can outpace mass flow relief, so pressure still climbs. Blocked outlets and thermal expansion are classic PSV cases when sized correctly. Fire case is explicitly covered in most codes, with higher allowable accumulation. The subtle trap is thinking a valve equals immunity, regardless of rate.