Vol.:(0123456789) 1 3 Metallography, Microstructure, and Analysis https://doi.org/10.1007/s13632-019-00544-1 TECHNICAL ARTICLE Efect of Processing Routes on Orientation‑Dependent Tensile Flow Behavior of Zircaloy‑4 at Elevated Temperatures K. Limbadri 1  · Swadesh Kumar Singh 2  · Kosaraju Satyanarayana 2  · A. K. Singh 3  · A. Maruthi Ram 4  · Mina Ravindran 4  · Mani Krishna 5  · M. Chaitanya Reddy 4  · Kurra Suresh 6 Received: 16 August 2018 / Revised: 23 December 2018 / Accepted: 22 April 2019 © ASM International 2019 Abstract The present work describes the correlation between orientation-dependent tensile fow behavior and texture of Zircaloy-4 sheet at elevated temperatures. The sheets are manufactured from three diferent routes, namely slab route, tube route, and pilgering. The material is tested at elevated temperatures raising from 75 to 225 °C with an increment of 75 °C. The XRD results show that the texture intensity is more in LOS than that of the other two. In all the three alloys, irrespective of tem- perature, the yield strength is maximum in transverse direction and minimum in longitudinal direction. The yield strength dependent in-plane anisotropy (A IP ) and percent of elongation-dependent anisotropy (δ) values show presence of moder- ate textures. The true stress and true plastic strain values are best ftted with the Holloman equation, and the coefcient of determination (R 2 ) ranges between 0.99039 and 0.99959. The diferential curves are plotted by numerically diferentiating true stress with respect to true plastic strain for quantitative description of work-hardening rate of materials. The diferential curves of all the three alloys exhibit the three typical work-hardening regions (i.e., elasto-plastic transition, easy glide stage, dynamic recovery). Keywords Zircaloy-4 · Texture · Anisotropy index · Tensile properties · Instantaneous work-hardening curves Introduction The Zircaloy-4 is one of the promising structural alloys in nuclear industry due to its elevated temperature corrosion resistance [1], low thermal neutron absorption cross section [2], and high creep strength [3]. Therefore, it is used as fuel cladding tubes for storing uranium oxide pellets and the ends of tubes are sealed with resistance butt welding [4]. It is also used for manufacturing spacer grid assembly and other structural elements in nuclear industry. The spacer grid acts as a binder to hold the fuel rods. The spacer grid assembly consists of an array of grid cells. In each cell, sheet metal is bent three times perpendicularly to form rectangular shape. Further, each strip has series of projections to enclose the cladding tubes in correct loca- tion. The perpendicular bends and series of projections are critical points where material is subjected to work hardened during the bending and formation of projections. Recently, the grid assembly design has numerically optimized [5]. Crush strength and integrity of fuel rod support were tested to suggest a suitable new form and manufacturing method- ology [6]. In both cases, the grid strips and fuel cladding tubes, the Zircaloy-4 sheets require metallurgical structural integrity to enhance its performance. The microstructural changes follow a sequence with steps involved in manu- facturing process. The sequence was observed as dendritic structure (after casting), widmanstatten structure (after * Swadesh Kumar Singh swadeshsingh@griet.ac.in K. Limbadri limbadrigriet@gmail.com 1 Marri Laxman Reddy Institute of Technology, Dundigal, Hyderabad 500043, India 2 Gokaraju Rangaraju Institute of Engineering and Technology, Hyderabad 500090, India 3 Defence Metallurgical Research Laboratory (DMRL), Hyderabad, India 4 Nuclear Fuel Complex, Hyderabad 500062, India 5 Bhabha Atomic Research Centre, Mumbai, India 6 Birla Institute of Technology and Science, Hyderabad 500090, India