Intergranular cracks of the steel are easy to occure, when the brazing brass alloy is deposited on the steel in which residual tensile stress is present. These cracks are caused by solder brittleness, that is, the brazing alloy intrudes into and weaken grain boundaries of the steel under the condition of the existence of tensile stress at high temperature. According to the high temperature stress rupture test, solder brittleness by brass brazing alloy commences at the lower temperature than melting point of the alloy, and its tendency increases with rising temperature. Near and above the melting point of the alloy, the brazed specimens rupture almost instantly by considerably low stress without showing no sign of creep. Brazing alloy intrusions into grain boundaries do not take place without stress, and increasing stress increases the tendency to solder brittleness. Silver brazing alloy has less tendency to solder brittleness than brass.In order to avoid the cracking by solder brittleness, it is necessary to eliminate residual tensile stress before brazing by stress relief annealing or other methods. Brazing with silver brazing alloy also prevents cracking.