WWII and Liberty Ships brought metallurgy to the forefront. As some of the first welded vessels, many lessons were learned the hard way. Remember how fast they were building them - roughly 40 days from laying the keel to launching at the end.

One issue was "brittle fracture" fatigue, an almost ignored topic until then. Early losses were a mystery until one cracked in half in harbour [?Boston or Halifax?]. In the cold North Atlantic water, ships would split along a welded seam. They revised the welding techniques and materials after studying that incident.

A second was the fact a riveted failure would tend to stop at the rivet; just as the sidewalk will crack at the joints. But a overstressed [from a nearby explosion] riveted seam will just keep splitting.

Again, better welding helped. [Remember -- MANY of the nation's workers had never been in a shipyard before the war; and six million were women [en.wikipedia.org].

You can search on "Liberty Ship" and "Metal Fatigue" and get much more on this topic.