Nanohardness measurement of high-purity Fe–C martensite

Evaluation Technique of the Hardness and Elastic Modulus of Materials with Fine Microstructures

“…A typical measurement via a nanoindenter can record displacement h from the surface of the material and load P with resolutions in sub-nanometer and sub-mN, respectively. From the recorded P-h relations, various characteristics of the individual phases in a composite material, such as the elastic modulus, hardness, the strainhardening exponent, yield strength, fracture toughness, and residual stress 1,2) can be directly estimated. Among these properties, the elastic modulus, E, and hardness, H, are obtainable without complicated testing apparatus and spending.…”

Evaluation of Grain Boundary Effect on Strength of Fe–C Low Alloy Martensitic Steels by Nanoindentation Technique

“…To plot the nanohardness Hn (squares) with the Vickers hardness Hv on the same axis, Hn is converted to Hv using an empirical equation of Hn ¼ 2:5Hv for bcc single crystals with a 500 mN peak load condition that was shown in previous papers. 10,12) Additionally, nanohardness can be regarded as 0 plotted on the y axis because 0 indicates a stress for a sample with a grain size of infinity and corresponds to the matrix strength without any contribution of the grain boundary. On the other hand, the conventional micro-Vickers hardness (circles) for the two samples can be plotted using the grain size data obtained by the EBSD analysis described in Fig.…”

“…Figure 4 shows the grain distribution maps that were obtained by the EBSD analysis for the two samples. The solid lines represent misorientation angles that are larger than 10 . According to the variants model in the K-S relationship for the lath martensite, 16) the minimum misorientation angle is 10.53 among the four possible block boundaries with the same habit plane.…”

“…[6][7][8][9] Recent progress in nanoindentation technique has made it possible to evaluate the strength in nano scale. Ohmura et al [10][11][12][13] performed the nanoindentation measurement within a matrix of martensite and evaluated the strengthening factors of the matrix and the grain boundary separately. This study indicated that there is a significant grain boundary effect on the macroscopic strength.…”

Electrochemical Nanoindentation Study on Influence of Hydrogen on Local Mechanical Properties of Fcc Metals at Slow Strain Rate

“…Therefore, in order to elucidate the HE mechanism, characterization of influence of hydrogen on mechanical properties of small volume by means of local analytical tools is expected. Historically, nanoindentation (NI) has been employed to measure hardness, elastic modulus, and elastic limit of thin-film materials 2,3) or miniature structures, 4,5) and is considered promising for this purpose. At room temperature, hydrogen diffuses in metals and finally desorbs from the metal surface.…”