Microstructures and Mechanical Properties of a Commercial Pure Zirconium during Rolling and Annealing at Different Temperatures

Abstract

Zirconium (Zr) alloys have been widely applied in nuclear reactors due to their low probability of neutron capture, acceptable mechanical properties, and excellent corrosion resistance. [1-6] Zirconium alloys are commonly used as cladding tubes, fixed grids, or channel box in reactors. [2,3,6] The fabrication of Zr alloys components generally includes vacuum consumable melting, forging, extrusion, hot and cold rolling, recrystallization or stress relief annealing and so on. [7] Rolling and subsequent annealing are frequently used in the Zr alloy sheet and tube production, which actually determine the microstructure and texture, [7-10] thus playing a decisive role for the corrosion resistance, [11-14] creep resistance [15-17] and mechanical properties [18-20] of Zr alloys. Annealing can reduce the residual stress, recover the plastic deformation ability and tailor the grain size and texture, which plays a vital role in the Zr alloy fabrication. A special parameter was thus proposed to evaluate the effect of annealing. [21] The microstructure and the texture evolution during annealing are not only significantly affected by annealing condition, for example temperature [22,23] and holding time, [8,24] but also by the pre-annealing deformation. [6,25] Indeed, many research results on deformation and subsequent annealing in Zr alloys have been reported. Chen et al. [7] reported that the 30% rolling reduction combined with annealing at 580 C for 12 h imparted a superior plasticity to the Zr alloy. Kumara et al. [26] investigated the three stage of annealing in a moderately deformed Zr-4 alloy. They found that the changes in the misorientations, and corresponding rearrangements of dislocations, were the most efficient means of stress relief in Zr-4 alloy. Prakash et al. [27] investigated the microstructural and textural evolution of ZIRLO alloy during hot rolling at different temperatures. Their results show that the slip, twinning, and recrystallization played a role in the microstructure development during hot rolling. They also contributed to the texture development, lamellae break-up, and the formation of a bimodal microstructure. Jiang et al. [28] studied the effects of cold-rolling reduction, annealing temperature, and time on recrystallization behavior and kinetics of cold-rolled Zr-1Sn-0.3Nb-0.3Fe-0.1Cr alloy and found that the rate of the recrystallization increased with increasing annealing temperature and rolling reduction. Recrystallized grains nucleated preferentially at sites with high-density dislocation and deformation stored energy. Zhang et al. [29] studied the microstructure evolution and mechanical properties of Zr 98.2 Cr 1.8 during hot rolling, solution and aging treatment (STA). It was found the bimodal microstructure was the key factor to achieve high strength (ultimate tensile strength 818 MPa) and excellent ductility (18.4%) after STA at 750 C. Gerspach et al. [30] investigated the texture stability during primary recrystallization of cold-rolled Zr702 alloy and found that a small strain favored...

Texture and Twinning Evolution of Cold-Rolled Industrial Pure Zirconium

“…As a hexagonal metal, zirconium has been the subject of extensive research in the literature due to its applicability across various industries, including petrochemicals, military, nuclear power, aerospace, and nuclear reactions [1][2][3]. Specifically, industrial pure zirconium is widely utilized in the petrochemical industry, owing to its excellent corrosion resistance [4,5].…”