Research on constitutive equations and hot working maps of Incoloy028 alloy based on hot compression tests
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eng Tuo State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, Xi’an 710049, Shaanxi, People’s Republic of China; and Department of Manufacturing Technology, Stainless Steel Tube Branch Company, Taiyuan Iron & Steel (Group) CO. LTD, Taiyuan 030003, People’s Republic of China
Genshu Zhou State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, Xi’an 710049, Shaanxi, People’s Republic of China (Received 9 January 2016; accepted 28 March 2016)
Hot deformation behavior of Incoloye028 alloy was investigated by conducting hot compression tests on Gleeble-3800 simulator in the temperature range of 1223–1473 K and the strain rate range of 0.1–50 s1. True stress–true strain curves showed that the flow stress increases with the decrease of deformation temperature and the increase of strain rate. The constitutive equations of Incoloy028 alloy were obtained by introducing Zener–Hollomom parameter, the flow behavior can be described by the hyperbolic sine function and the activation energy changes with strain rate and temperature significantly. The hot working maps of Incoloy028 alloy were proposed on basis of dynamic materials model. The hot working maps for different strains indicated that there were two instability zones, one zone is in the temperatures range of 1423–1473 K and strain rate range of 0.1–50 s1, and another zone is in the temperature range of 1223–1423 K and strain rate range of 0.6–1 s1. The reasonable hot working temperature range is 1423–1473 K when strain rate is more than 50 s1.
I. INTRODUCTION
In the severe and complex corrosive oil and gas wells with high temperature and high pressure as well as with high H2S, CO2, Cl, and organic sulfur,1 the pipe must meet the requirements of good physical and mechanical properties and high corrosion resistance. Traditional stainless steels are difficult to serve in this harsh environment. Therefore, it is necessary to investigate a potential application of nickel-based alloys containing high content of chromium, nickel, and molybdenum as an oil well pipe material. Incoloy028 (Fe–Ni–Cr–Mo) alloy is a low carbon austenite alloy, in which the copper content is about 1% (weight). Because of low carbon content and high contents of chromium, molybdenum, and copper, its comprehensive corrosion resistance and chloride ion stress corrosion resistance are good, and more, excellent intercrystalline corrosion resistance. However, it is difficult to adopt the method of hot piercing process for Incoloy028 alloy due to its large hot deformation Contributing Editor: Jürgen Eckert a) Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/jmr.2016.157
resistance. Hot extrusion process is the unique method at present and the extrusion deformation only can be completed in a short period at high temperature by controlling the extrusion processing parameters, strain rate usually changes with ten orders of magnitude. The sine-hyperbolic equations are widely used for modeling flow stress evolutions
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