Attention should be paid to bonding defects and cracks, which are in no case admissible. A little more toleration may be shown to pores and non-metal inclusions. But a careful examination of heavily loaded parts of a structure should be carried out. Hot cracks, i.e. crystallization cracks, usually occur in the middle of the weld. Hotcracking sensibility is found in alloys, alloyed steels and steels containing a higher level of impurities, usually in welds of larger dimensions.
Cold cracks occur mostly in the heat affected zone.
They occur in steels susceptible to through-hardening and hydrogen embrittlement. A special attention should be paid to porosity in gas-shielded welding, submerged arc welding, and welding with basic electrodes. Typical cracks in the welded joint and location of their appearance is shown in Fig. Characteristic location of cracks Fig. 1. The method seems to be less reliable in detecting planar, i.e. two-dimensional, defects such as cracks.