The relationship between the retained austenite content of the matrix in16Cr-3C white irons and the abrasion resistance was investigated. The results show that: (1) theabrasion resistance can be improved by sub-critic...The relationship between the retained austenite content of the matrix in16Cr-3C white irons and the abrasion resistance was investigated. The results show that: (1) theabrasion resistance can be improved by sub-critical heat treatment, which could be attributed to thedecrease of the retained austenite content; (2) both the abrasion resistance and hardness can beimproved by controlling the retained austenite content below 20 percent-30 percent and arrive at themaximum when the retained austenite content is reduced to about 10 percent; (3) the abrasionresistance decreases abruptly once the retained austenite content is lower than 10 percent, whichstems from both the in situ transformation of (Fe, Cr)_(23)C_6 to M_3C carbides and the formation ofpearlitic matrix.展开更多
The creep behavior of Al2O3.SiO2 fiber reinforced ZL109 composites has been investigated at four temperatures ranging from 553 to 623 K. The results show high stress exponent and high apparent creep activation energy....The creep behavior of Al2O3.SiO2 fiber reinforced ZL109 composites has been investigated at four temperatures ranging from 553 to 623 K. The results show high stress exponent and high apparent creep activation energy. A good correlation between the normalized creep rate and normalized effective stress means that the true stress exponent of minimum creep strain rate of the composite is very close to 5, and the minimum creep strain rate is matrix lattice diffusion controlled. The threshold stress decreases with increasing temperature linearly and disappears at a temperature close to 623 K. It is assumed that the long range internal back stresses generated in creep reduce the load transfer to fibers and the interaction between dislocations and strengthening precipitates decreases at high temperature. At a high temperature where the long range internal back stresses is very close to the applied stress, the threshold stress disappears.展开更多
文摘The relationship between the retained austenite content of the matrix in16Cr-3C white irons and the abrasion resistance was investigated. The results show that: (1) theabrasion resistance can be improved by sub-critical heat treatment, which could be attributed to thedecrease of the retained austenite content; (2) both the abrasion resistance and hardness can beimproved by controlling the retained austenite content below 20 percent-30 percent and arrive at themaximum when the retained austenite content is reduced to about 10 percent; (3) the abrasionresistance decreases abruptly once the retained austenite content is lower than 10 percent, whichstems from both the in situ transformation of (Fe, Cr)_(23)C_6 to M_3C carbides and the formation ofpearlitic matrix.
文摘The creep behavior of Al2O3.SiO2 fiber reinforced ZL109 composites has been investigated at four temperatures ranging from 553 to 623 K. The results show high stress exponent and high apparent creep activation energy. A good correlation between the normalized creep rate and normalized effective stress means that the true stress exponent of minimum creep strain rate of the composite is very close to 5, and the minimum creep strain rate is matrix lattice diffusion controlled. The threshold stress decreases with increasing temperature linearly and disappears at a temperature close to 623 K. It is assumed that the long range internal back stresses generated in creep reduce the load transfer to fibers and the interaction between dislocations and strengthening precipitates decreases at high temperature. At a high temperature where the long range internal back stresses is very close to the applied stress, the threshold stress disappears.
