FRACTURE STATISTICS USING THREE-PARAMETER AND TWO-PARAMETER WEIBULL DISTRIBUTIONS FOR Fe-0.4C-1.5Cr-1.5Ni-0.8Mn-0.2Mo STRUCTURAL SINTERED STEEL

A statistical analysis is presented of tensile and bending strengths of a porous sintered structural steel which exhibits non-linear, quasi-brittle, behaviour. It is the result of existing natural flaws (pores and oxide inclusions) and of the formation of fresh flaws when stress is applied. The analysis is by two- and three-parameter Weibull statistics. Weibull modulus, a measure of reliability, was estimated by the maximum likelihood method for specimen populations < 30. Probability distributions were compared on the basis of goodness to fit using the Anderson-Darling tests. The use of the two- parameter Weibull distribution for strength data of quasi-brittle sintered steels is questioned, because there is sufficient evidence that the 3-parameter distribution fits the data better.