Liberty ships were a case study in one of my metallurgy classes (welding) in college. Early ones had a reputation of literately splitting in half during their voyage in the cold north Atlantic waters.
From wiki:
Early Liberty ships suffered hull and deck cracks, and a few were lost due to such structural defects. During World War II there were nearly 1,500 instances of significant brittle fractures. Twelve ships, including three of the 2,710 Liberty ships built, broke in half without warning, including SS John P. Gaines,[23][24] which sank on 24 November 1943 with the loss of 10 lives. Suspicion fell on the shipyards, which had often used inexperienced workers and new welding techniques to produce large numbers of ships in great haste.[citation needed]
The Ministry of War Transport borrowed the British-built Empire Duke for testing purposes.[25] Constance Tipper of Cambridge University demonstrated that the fractures did not start in the welds, but were due to the embrittlement of the steel used;[26] however, the same steel used in riveted construction did not have this problem. She discovered that at a certain temperature, the steel the ships were made from changed from being ductile to brittle. This allowed cracks to form and propagate. This temperature is known as the critical ductile-brittle transition temperature. Ships in the North Atlantic were exposed to temperatures that could fall below this critical point.[27] The predominantly welded hull construction, effectively a continuous sheet of steel, allowed small cracks to propagate unimpeded, unlike in a hull made of separate plates riveted together. One common type of crack nucleated at the square corner of a hatch which coincided with a welded seam, both the corner and the weld acting as stress concentrators. Furthermore, the ships were frequently grossly overloaded, increasing stress, and some of the problems occurred during or after severe storms that would further have increased stress. Minor revisions to the hatches and various reinforcements were applied to the Liberty ships to arrest the cracking problem. The successor Victory ships used the same steel, also welded rather than riveted, but spacing between frames was widened from 30 inches (760 mm) to 36 inches (910 mm), making the ships less stiff and more able to flex.[28]
Another interesting source/summary of the issues:
https://metallurgyandmaterials.wordpress.com/2015/12/25/liberty-ship-failures/
