Influence of Inclusions on Crack Growth Life of Powder Metallurgy

The influence of inclusion on crack Stress Intensity Factor(SIF) of Powder Metallurgy(PM) FGH 95 was investigated using singular element method with fine mesh at crack front.The effect of inclusion on crack growth life of PM was also calculated by Paris formula.The result indicates that the influence of inclusions on crack SIF of PM changes with the alteration of the inclusion's location relative to the crack.When the crack is in the range of three times of the inclusion's radius,the inclusion can affect the SIF and it will not affect on it if the crack exceeds this range.When the radius of the crack approaches the radius of the inclusion,the influence of soft inclusions on SIF is contrary to the rigid inclusions.For the crack growth life,the influence of soft inclusion is also contrary to the rigid inclusions.The crack growth life without inclusions is shorter than with soft inclusions,but it is longer than that with rigid inclusions.Because the elastic module of the inclusion is smaller than the matrix,the inclusion in FGH95 is soft inclusion and the crack growth life without inclusions is longer than that with inclusions in FGH95.The conclusion can make the analysis of the PM turbine disks life simpler.