Assessment of the anisotropic flow stress and plastic strain of Zr–2.5%Nb pressure tubes at temperature from 25°C to 300°C

Deducing the stress–strain response of anisotropic Zr–2.5%Nb pressure tubing by spherical indentation testing

“…for a given value of h, when the indentation is made on the TN plane compared to the RN or AN planes of the pressure tube. This is consistent with the known mechanical anisotropy of the extruded and cold-drawn Zr-2.5%Nb pressure tube material which dictates that the yield stress in the transverse (circumferential) direction is significantly larger than in the axial or the radial directions of the tube [23,24,[27][28][29][30][31][32][33][34].…”

“…6 shows the r avg Àe avg curves from our spherical indentation tests performed at 300°C in the TN and AN directions. This figure includes additional r avg Àe avg data from previously reported uniaxial tension and compression tests performed on the Zr-2.5%Nb material [30]. Similar results were also obtained in the RN direction and at test temperatures of 25°C, 100°C, and 200°C, and the close correspondence in the r avg Àe avg curves with those obtained from conventional uniaxial stress tests validate the method adopted here to determine r avg Àe avg from the spherical indentation P-h data.…”

“…In a recent study we performed uniaxial compression tests to measure r AN yield r RN yield , and r TN yield of Zr-2.5%Nb pressure tube material at temperature from 25°C to 300°C and found that F = 0.38, G = 0.202 and H = 0.62 [30]. We observed that these coefficients were not strongly dependent upon temperature, over the range from 25°C to 300°C, or upon plastic strain.…”

“…The tube was fabricated by 11:1 extrusion of an annular billet at 720°C followed by 27% cold-drawing at room temperature and a 24 h stress relief autoclave treatment at 400°C [23][24][25][26][27]. The mechanical properties of this pressure tube have been studied extensively with uniaxial compression tests and with micro-indentation testing [23,24,[27][28][29][30][31][32][33][34]. Cube-shaped samples, with sides of about 4 mm length, were cut from the pressure tube.…”

“…(1)- (3). The values of yield stress r yield and strain hardening exponent n used for the analysis in this study with respect to direction have been previously reported [29,30]. for a given value of h, when the indentation is made on the TN plane compared to the RN or AN planes of the pressure tube.…”