STRESS-RELIEF HEAT TREATMENT OF MANGANESE-NICKEL-ALUMINUM BRONZE AND MANGANESE-BRONZE WELDMENTS

摘要

Tensile properties, weldability, general corrosion, and corrosion-fatigue properties were determined as a function of stress-relief heat treatment for both cast Mn-Ni-Al bronze and manganese-bronze propeller alloys. It was found that Mn-Ni-Al bronze is susceptible to stress-corrosion cracking in the as-welded heat-affected zone. Stress-relief heat treatments in the range of 700 to 1200F were effective in eliminating the stress-corrosion cracking in this alloy. Manganese-bronze weldments exhibited poor weldability but were not found susceptible to stress-corrosion cracking. High-cycle corrosion-fatigue tests on weldments revealed an endurance strength at 10 to the 8th power cycles of 12,000 pounds per square inch for Mn-Ni-Al bronze and 7,500 to 11,000 pounds per square inch for manganese bronze.