A  « Case Studies in E
ngineering Failure Analysis » published on ScienceDirect.com.

High strength low alloy (HSLA) steel with a nominal composition of 0.15C–1.25Cr–1Mo–0.25V is being extensively used in space programme. Owing to its ease of fabrication and welding, a tank was fabricated out of this alloy. The tank is used to contain strontium per chlorate which on combustion develop secondary thrust, effectively used during attitude control of satellite launch vehicle. During one of the routine qualification tests, a tank had failed at an internal pressure of 109 bar, against a designed proof pressure of 120 bar.

Failure was initiated from long seam weld of a cylindrical shell and propagated into the parent material thereafter. Detailed metallurgical investigation has been carried out to understand the cause of failure. …..Read more