Failure analysis of leaded brass bolt

•The crack initiation region was located at the thread bottom.•The coarse Pb particles in β′ phase may have been the location of crack initiation.•Dissolution of the zinc-rich phase initiates the formation and propagation of cracks.•A partial ductile failure was in α-phase and a cleavage failure was in β́-phase.•The mechanical stress had a supportive effect on the SCC crack propagation mechanism.