The Effect of Lead on Micro-Crack Initiation and Propagation in Alloy Steels. The Effect of Composition and Test Conditions on Lead-Embrittlement of Steel

摘要

The effects of composition grain size, strain rate and other variables on the lead-embrittlement of steels were studied. The lead embrittlement of steel was observed as a loss in ductility and true fracture strength of heat treated steel tested at elevated temperatures in the presence of lead. The embrittlement was seen when the lead was present either internally in the steel (leaded steel) or soldered to the surface. The phenomenon was found to exist over a range of temperatures from about 300F (i.e. more than 300 F below the melting point of lead) to a brittle-to-ductile transition temperature which ranged from 700 F to over 900 F depending on a number of factors B. It was found that the embrittlement varied with composition and seemed, at an equivalent strength level, to be more severe the lower the carbon or alloy content of the steel. The lead content of a leaded steel was found to be unimportant, but the composition of the lead was critical. Other variables which were studied included grain size, loading rate, prior plastic straining at room temperature and cyclic loading.