TY - GEN
T1 - Elevated temperature fracture toughness of P/M Al-Fe-V-Si
AU - Porr, William C.
AU - Leng, Yang
AU - Gangloff, Richard P.
PY - 1991
Y1 - 1991
N2 - The effects of temperature and loading rate on the crack initiation and growth fracture toughnesses of powder metallurgy Al-8.5Fe-1.7Si-1.3V (wt%) were investigated by an elastic-plastic J-integral method with electric potential difference crack monitoring. At 25°C the ultrafine-grained P/M alloy exhibits high crack initiation toughness (KIC = 36.6 MPa/m) and crack growth resistance (TR = [E/σo2] [dJ/da] = 20.6) in the LT orientation orientation compared to the behavior of ingot metallurgy alloy 2618 (KIC = 21 MPa/m and TR = 0.5). While the toughness of the ingot-metallurgy alloy is constant (KIC) or increases mildly (TR) with temperature to the aging level of 199°C, both measures of toughness for the P/M alloy decrease between 25°C and 316°C, with minima in KIC and TR at 200°C. KIC decreases and TR increases mildly with increasing temperature for FVS0812 tested in the TL orientation. KIC and TR decrease with decreasing applied load line displacement rate for LT FVS0812 at 175°C, with crack growth resistance exhibiting a minimum. The mode of fracture is microvoid coalescence in all cases, however, the origins and evolution of damage are unclear. The TL toughness of FVS0812 is generally low because of prior particle boundary oxides oriented parallel to the fracture path. The behavior of LT FVS0812 is explained by a complex interaction of prior particle boundary delamination, perpendicular to the main crack front to promote plane stress 'thin sheet toughening', and several possible intrinsic fracture mechanisms. Speculatively, intrinsic toughness decreases with increasing temperature and loading time because of dynamic strain aging from solid solution Fe or environmental hydrogen embrittlement.
AB - The effects of temperature and loading rate on the crack initiation and growth fracture toughnesses of powder metallurgy Al-8.5Fe-1.7Si-1.3V (wt%) were investigated by an elastic-plastic J-integral method with electric potential difference crack monitoring. At 25°C the ultrafine-grained P/M alloy exhibits high crack initiation toughness (KIC = 36.6 MPa/m) and crack growth resistance (TR = [E/σo2] [dJ/da] = 20.6) in the LT orientation orientation compared to the behavior of ingot metallurgy alloy 2618 (KIC = 21 MPa/m and TR = 0.5). While the toughness of the ingot-metallurgy alloy is constant (KIC) or increases mildly (TR) with temperature to the aging level of 199°C, both measures of toughness for the P/M alloy decrease between 25°C and 316°C, with minima in KIC and TR at 200°C. KIC decreases and TR increases mildly with increasing temperature for FVS0812 tested in the TL orientation. KIC and TR decrease with decreasing applied load line displacement rate for LT FVS0812 at 175°C, with crack growth resistance exhibiting a minimum. The mode of fracture is microvoid coalescence in all cases, however, the origins and evolution of damage are unclear. The TL toughness of FVS0812 is generally low because of prior particle boundary oxides oriented parallel to the fracture path. The behavior of LT FVS0812 is explained by a complex interaction of prior particle boundary delamination, perpendicular to the main crack front to promote plane stress 'thin sheet toughening', and several possible intrinsic fracture mechanisms. Speculatively, intrinsic toughness decreases with increasing temperature and loading time because of dynamic strain aging from solid solution Fe or environmental hydrogen embrittlement.
UR - https://www.scopus.com/pages/publications/0025890497
M3 - Conference Paper published in a book
AN - SCOPUS:0025890497
SN - 0873391705
T3 - Conf Proc Low Density High Temp Powder Metall Alloys
SP - 129
EP - 155
BT - Conf Proc Low Density High Temp Powder Metall Alloys
PB - Publ by Minerals, Metals & Materials Soc (TMS)
T2 - Conference Proceedings on Low Density, High Temperature Powder Metallurgy Alloys
Y2 - 7 October 1990 through 11 October 1990
ER -