Embrittlement of 4340 Type Steel by Liquid Lead and Antimony and Lead-Antimony Solutions.
ARMY ARMAMENT RESEARCH AND DEVELOPMENT CENTER WATERVLIET NY LARGE CALIBER WEAPON SYSTEMS LAB
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A study has been made of the fracture behavior of single-edge notched specimens of 4340 type steel tested in cyclic fatigue at temperatures ranging from 675 F to 1350 F in high purity lead and antimony and liquid lead containing 5 to 75 percent antimony in solution. The susceptibility to embrittlement by liquid lead decreases with temperature. The fracture mode changes from intergranular at low temperatures to ductile at 1200 F. In lead solutions, at low temperatures 700 F and low concentrations of antimony 5 to 25 percent, embrittlement is caused by liquid lead only. At high temperatures 1000 to 1200 F and high concentrations of antimony 35 to 75 percent Sb, antimony is the primary embrittling species. Antimony induced embrittlement by lead-antimony solutions occurs by intergranular fracture mode. This variation in susceptibility to embrittlement with temperature indicates that at low temperatures embrittlement is caused by liquid lead and occurs by reduction in cohesion mechanism while at elevated temperatures embrittlement is induced by antimony and occurs by temperature dependent grain boundary diffusion controlled processes. These and other results are also discussed in terms of the current understanding of liquid metal and temper embrittlement of metals.
- Metallurgy and Metallography