Experimental and Modeling Studies on the Stress Relaxation Behaviour of Ti-6Al-4V Alloy

2021 ◽  
Author(s):  
Kali Prasad ◽  
Krishnaswamy Hariharan ◽  
Dilip K. Banerjee
Keyword(s):  
Stress Relaxation ◽  
Titanium Alloys ◽  
Room Temperature ◽  
Hold Time ◽  
High Strength ◽  
Uniaxial Tensile ◽  
Time Data ◽  
Transient Stress ◽  
Ti Alloys ◽  
Strain And Strain Rate

Abstract The transient mechanical behavior of materials during stress relaxation has evoked interest in manufacturing applications because of the effect of stress relaxation on formability enhancement. However, most of the previous studies have focused on advanced high strength steels and aluminum alloys. Limited transient stress relaxation studies have been conducted on titanium alloys in order to understand the influence of stress relaxation on forming behavior. Titanium alloys are widely used in aerospace components because of their high strength to weight ratios and excellent fatigue strengths. However, room temperature formability of Ti alloys is an important concern, which restricts their widespread use in various applications. To address these challenges, the present study is aimed to understand the role of transient stress relaxation on formability of Ti alloys. Toward this end, stress relaxation of a dual phase titanium alloy (Ti-6Al-4V) has been investigated experimentally. Stress relaxation tests were performed by interrupting uniaxial tensile tests in the uniform deformation regime for a pre-defined strain and hold time after which tests were continued monotonically until fracture. Single step, room temperature stress relaxation experiments were performed systematically to study the effect of hold time, pre-strain, and strain rate on mechanical properties. The stress relaxation phenomenon was found to contribute positively to the ductility improvement. The mechanisms responsible for enhancing the formability are discussed. The experimentally obtained stress vs. time data were analyzed using a advanced constitutive model for stress relaxation available in literature.

Effect of Stress Relaxation on Springback of Steel Sheet in Warm Forming

2016 ◽  
Vol 725 ◽  
pp. 671-676 ◽  
Author(s):  
Naoko Saito ◽  
Mitsugi Fukahori ◽  
Daisuke Hisano ◽  
Hiroshi Hamasaki ◽  
Fusahito Yoshida
Keyword(s):  
Stress Relaxation ◽  
High Strength Steel ◽  
Room Temperature ◽  
Steel Sheet ◽  
Elevated Temperatures ◽  
High Strength ◽  
Warm Forming ◽  
Sheet Metals ◽  
Stress Relaxation Behavior ◽  
Increasing Temperature

Springback of a high strength steel (HSS) sheet of 980 MPa grade was investigated at elevated temperatures ranging from room temperature to 973 K. From U-and V-bending experiments it was found that springback was decreased with increasing temperature at temperatures of above 573 K. Furthermore, springback was decreased with punch-holding time because of stress relaxation. In this work, the stress relaxation behavior of the steel was experimentally measured. By using an elasto-vicoplasticity model, the stress relaxation was described, and its effect on the springback of sheet metals in warm forming was discussed theoretically.

Current Research Situation and Development of Titanium Alloy in China in Recent Five Years

2005 ◽  
Vol 475-479 ◽  
pp. 563-568
Author(s):  
Yong Qing Zhao ◽  
Lian Zhou
Keyword(s):  
Titanium Alloy ◽  
High Temperature ◽  
Titanium Alloys ◽  
High Strength ◽  
Basic Theory ◽  
Ti Alloys ◽  
Developing Directions ◽  
Research Situation

China pays great attentions to the development of titanium alloys and their basic theory because of their excellent properties. New titanium alloys and their new basic theories developed in China in recent five years were reviewed, for example, high temperature Ti alloys, burn resistant titanium alloys, high strength and middle strength titanium alloys and so on. The developing directions in the next 5 to 10 years were forecast.

scholarly journals Comparative Corrosion Behavior of Two Palladium-Containing Titanium Alloys

2006 ◽  
Author(s):  
Tiangan Lian ◽  
Takashi Yashiki ◽  
Takenori Nakayama ◽  
Tomoaki Nakanishi ◽  
Rau´l B. Rebak
Keyword(s):  
Titanium Alloys ◽  
Corrosion Behavior ◽  
High Strength ◽  
Yucca Mountain ◽  
Short Term ◽  
Corrosion Resistant ◽  
Electrochemical Testing ◽  
Ti Alloys ◽  
Potentiodynamic Curves ◽  
Titanium Grade

The ASTM standard B 265 provides the requirements for the chemical composition of titanium (Ti) alloys. It is planned to use corrosion resistant and high strength titanium alloys to fabricate the drip shield at the proposed Yucca Mountain Repository. Titanium grade (Gr) 7 (R52400) and other Ti alloys are currently being characterized for this application. Ti Gr 7 contains 0.15% Palladium (Pd) to increase its corrosion performance. In this article we report results on the comparative short term corrosion behavior of Ti Gr 7 and a Ruthenium (Ru) containing alloy (Ti Gr 33). Ti Gr 33 also contains a small amount of Pd. Limited electrochemical testing such as polarization resistance and cyclic potentiodynamic curves showed that both alloys have a similar corrosion behavior in the tested environments.

Improvement in Ductility in Commercially Pure Titanium Alloys by Stress Relaxation at Room Temperature

2014 ◽  
Vol 611-612 ◽  
pp. 92-98 ◽  
Author(s):  
Irena Eipert ◽  
Giribaskar Sivaswamy ◽  
Rahul Bhattacharya ◽  
Muhammad Amir ◽  
Paul Blackwell
Keyword(s):  
Stress Relaxation ◽  
Titanium Alloys ◽  
Yield Point ◽  
Room Temperature ◽  
Pure Titanium ◽  
Tensile Tests ◽  
Tensile Behaviour ◽  
Strain Rates ◽  
Commercially Pure Titanium ◽  
Commercially Pure

Present work focusses on the effect of stress relaxation on the tensile behaviour of two commercially pure titanium alloys of different strength levels (Grade 1 and Grade 4) subjected to tensile tests at room temperature. The stress relaxation tests were performed by interrupting the tensile tests at regular strain intervals of 5% in the plastic region of the tensile curve and compared to the monotonic tensile tests at different strain rates ranging from 10-4to 10-1s-1. To understand the effect of anisotropy, samples were taken along 0° and 90° to rolling direction (RD) for both the alloys. Improvement in ductility of different levels at all the strain rates was observed in both the alloys when stress relaxation steps were introduced as compared to monotonic tests. However there is not much change in the flow stress as well as in strain hardening behaviour of the alloys. The true stress-true strain curves of Grade 4 samples taken in 90° to RD exhibited discontinuous yielding phenomenon after the yield point, which is termed as a yield-point elongation (YPE). The improvement in ductility of the Cp-Ti alloys can be linked to recovery process occurring during the stress relaxation steps which resulted in the improvement in ductility after repeated interrupted tensile tests. The paper presents and summarise the results based on the stress relaxation for the two different alloys.

The Role of Deformation Twinning on Creep of Titanium Alloys

2007 ◽  
Vol 561-565 ◽  
pp. 121-126
Author(s):  
Sreeramamurthy Ankem ◽  
P. Gregory Oberson
Keyword(s):  
Titanium Alloys ◽  
Speed Of Sound ◽  
Critical Stress ◽  
National Science Foundation ◽  
Room Temperature ◽  
Deformation Twinning ◽  
Ti Alloys ◽  
National Science ◽  
Recent Developments

Normally, deformation twinning is a process that occurs at rates approaching the speed of sound in bulk metals once a critical stress has been reached. However, recently it has been shown that twins grow at speeds many orders of magnitude lower than the speed of sound during room temperature creep of titanium alloys. The net result is that this twinning process can contribute to the low-temperature (less than 0.25*Tm) creep behavior of α, α−β, and β−titanium alloys. For example, α-Ti alloys with small grain size do not extensively deform by twinning and hence show little overall creep strain. These recent developments are reviewed in this paper. This work is funded by the National Science Foundation under Grant Number DMR-0517351.

scholarly journals Susceptibility to Pitting Corrosion of Ti-CP2, Ti-6Al-2Sn-4Zr-2Mo, and Ti-6Al-4V Alloys for Aeronautical Applications

Metals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1002
Author(s):  
Jesus Jaquez-Muñoz ◽  
Citlalli Gaona-Tiburcio ◽  
Alejandro Lira-Martinez ◽  
Patricia Zambrano-Robledo ◽  
Erick Maldonado-Bandala ◽  
...  
Keyword(s):  
Corrosion Rate ◽  
Titanium Alloys ◽  
High Performance ◽  
Room Temperature ◽  
Corrosion Potential ◽  
Passive Layer ◽  
Ti Alloys ◽  
Power Spectral ◽  
Electrochemical Parameters ◽  
Cyclic Potentiodynamic Polarization

Titanium alloys are used in different industries like biomedical, aerospace, aeronautic, chemical, and naval. Those industries have high requirements with few damage tolerances. Therefore, they are necessary to use materials that present fatigue, mechanical, and corrosion resistance. Although Ti-alloys are material with high performance, they are exposed to corrosion in marine and industrial environments. This research shows the corrosion behavior of three titanium alloys, specifically Ti CP2, Ti-6Al-2Sn-4Zr-2Mo, and Ti-6Al-4V. Alloys were exposed on two electrolytes to a 3.5 wt % H2SO4 and NaCl solutions at room temperature using cyclic potentiodynamic polarization (CPP) and electrochemical noise (EN) according to ASTM G61 and ASTM G199 standards. CPP technique was employed to obtain electrochemical parameters as the passivation range (PR), corrosion type, passive layer persistence, corrosion potential (Ecorr), and corrosion rate. EN was analyzed by power spectral density (PSD) in voltage. Results obtained revealed pseudopassivation in CPP and PSD exposed on NaCl for Ti-6Al-2Sn-4Zr-2Mo, indicating instability and corrosion rate lower. However, Ti-6Al-4V presented the highest corrosion rate in both electrolytes. Ti-6Al-2Sn-4Zr-2Mo revealed pseudopassivation in CPP and PSD in NaCl, indicating a passive layer unstable. However, the corrosion rate was lower in both solutions.

scholarly journals Understanding Room Temperature Deformation of High-Strength Titanium Alloys

2021 ◽  
Vol 27 (S1) ◽  
pp. 28-29
Author(s):  
John Foltz ◽  
Shaolou Wei ◽  
Luis Ruiz-Aparicio ◽  
Andy Martinez ◽  
C. Cem Tasan
Keyword(s):  
Titanium Alloys ◽  
Room Temperature ◽  
High Strength ◽  
Temperature Deformation

Textural Evolution Evaluated by EBSD and XRD after Thermal Treatment in Ni-Ti Shape Memory Alloy

2011 ◽  
Vol 702-703 ◽  
pp. 884-887
Author(s):  
S.B. Ribeiro ◽  
T.G. Andrade ◽  
A.D.S. Paula ◽  
Jefferson Fabricio Cardoso Lins ◽  
K.K. Mahesh ◽  
...  
Keyword(s):  
Thermal Treatment ◽  
Shape Memory ◽  
Room Temperature ◽  
High Strength ◽  
Nickel Titanium ◽  
X Ray Diffraction ◽  
Transformation Temperatures ◽  
Textural Evolution ◽  
Ti Alloys ◽  
Hardness Tests

The Nickel-Titanium (Ni-Ti) alloys are the most attractive amongst shape memory alloys (SMA) due to their good functional properties coupled with high strength and good ductility. The transformation temperatures in Ni-Ti SMA can be altered by chemical composition and thermal and/or mechanical treatments adequate to obtain reversible martensitic transformation in one or more steps. The goal of the present work is to investigate the evolution of texture in Ni-Rich Ni-Ti (50.8at%Ni-Ti) SMA showing different phase transformation temperatures as a result of different thermal/mechanical history: straight-annealed (as-received condition) and subsequent thermal treatment at 500°C for 30 minutes in air. The microstructural and textural results were obtained by Electron Backscattering Diffraction on Scanning Electronic Microscopy (ESBD/SEM) and by X Ray Diffraction (XRD) at room temperature. Mechanical properties were measured by Vickers micro hardness tests at room temperature.

A Modified Constitutive Model for Tensile Flow Behaviors of BR1500HS Ultra-High-Strength Steel at Medium and Low Temperature Regions

2018 ◽  
Vol 37 (1) ◽  
pp. 39-57
Author(s):  
Jun Zhao ◽  
Guo-Zheng Quan ◽  
Jia Pan ◽  
Xuan Wang ◽  
Dong-Sen Wu ◽  
...  
Keyword(s):  
Low Temperature ◽  
Constitutive Model ◽  
Strain Rate ◽  
Relative Error ◽  
High Strength ◽  
Uniaxial Tensile ◽  
Stress Strain ◽  
Element Analysis ◽  
Strain And Strain Rate ◽  
Average Absolute Relative Error

AbstractConstitutive model of materials is one of the most requisite mathematical model in the finite element analysis, which describes the relationships of flow behaviors with strain, strain rate and temperature. In order to construct such constitutive relationships of ultra-high-strength BR1500HS steel at medium and low temperature regions, the true stress-strain data over a wide temperature range of 293–873 K and strain rate range of 0.01–10 s−1 were collected from a series of isothermal uniaxial tensile tests. The experimental results show that stress-strain relationships are highly non-linear and susceptible to three parameters involving temperature, strain and strain rate. By considering the impacts of strain rate and temperature on strain hardening, a modified constitutive model based on Johnson-Cook model was proposed to characterize flow behaviors in medium and low temperature ranges. The predictability of the improved model was also evaluated by the relative error ($W(\%)$), correlation coefficient (R) and average absolute relative error (AARE). The R-value and AARE-value for modified constitutive model at medium and low temperature regions are 0.9915 & 1.56 % and 0.9570 & 5.39 %, respectively, which indicates that the modified constitutive model can precisely estimate the flow behaviors for BR1500HS steel in the medium and low temperature regions.

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