Micromechanical behavior of a fine-grained China Low Activation Martensitic (CLAM) steel under nanoindentation was studied in this work. The grain size of the as-prepared O.lTi-CLAM steel is ~5μm and the average diam...Micromechanical behavior of a fine-grained China Low Activation Martensitic (CLAM) steel under nanoindentation was studied in this work. The grain size of the as-prepared O.lTi-CLAM steel is ~5μm and the average diameter of the spherical precipitates is ~5 nm. Both elastic modulus and hardness decrease with increasing contact depth of the nanoindenter, following an exponential decreasing function. The abnormally large contact depths should be resulted from defect concentration under the indenter. The effect of nanosized precipitates on hardness is responsible for the pop-ins occurring in the load-depth curves, corresponding to the blockage of nanosized precipitates to the dislocation movement. Nanosized VC and M23C6precipitates with the volume fractions of 0.32% and 1.21% can be identified, respectively. Different strengthening mechanisms originated from the two types of nanosized precipitates. The blockage of dislocations by VC particles leads to an Orowan strengthening whilst dislocations could cut through theM23C6particles because of the large size of the particles. The strengthening effects originated from the VC and M23C6 precipitates lead to the strength increase of .448 MPa and .254 MPa, respectively.展开更多
基金project is supported by the National Natural Science Foundation of China (NSFC, Grant Nos. 51574079, U1460204, U1660117)the National Key Research and Development Program of China (No. 2016YFB0300602)
文摘Micromechanical behavior of a fine-grained China Low Activation Martensitic (CLAM) steel under nanoindentation was studied in this work. The grain size of the as-prepared O.lTi-CLAM steel is ~5μm and the average diameter of the spherical precipitates is ~5 nm. Both elastic modulus and hardness decrease with increasing contact depth of the nanoindenter, following an exponential decreasing function. The abnormally large contact depths should be resulted from defect concentration under the indenter. The effect of nanosized precipitates on hardness is responsible for the pop-ins occurring in the load-depth curves, corresponding to the blockage of nanosized precipitates to the dislocation movement. Nanosized VC and M23C6precipitates with the volume fractions of 0.32% and 1.21% can be identified, respectively. Different strengthening mechanisms originated from the two types of nanosized precipitates. The blockage of dislocations by VC particles leads to an Orowan strengthening whilst dislocations could cut through theM23C6particles because of the large size of the particles. The strengthening effects originated from the VC and M23C6 precipitates lead to the strength increase of .448 MPa and .254 MPa, respectively.
