In this Issue: Thank you for taking the time to stay up-to-date on what's going on in the Gleeble Community. This month's newsletter features the following updates:
Come see a LUMet system in action at DSI's facility in Upstate New York. DSI will have a system available for demonstrations from August 22 - September 1st. If you are interested in learning more about this unique technology, please contact our team to schedule a visit. (info@gleeble.com)
LUMet Overview:
A Gleeble equipped with a LUMet system allows researchers to monitor metallic microstructures in real time, in-situ and at high temperatures while conducting physical simulations. The LUMet system provides unprecedented capabilities by allowing observation of the internal physical state of a specimen during Gleeble tests.
Researchers can gather in-situ information on:
Recrystallization
Phase transformations
Grain growth
Elastic constants
Grain size
Texture
Laser-ultrasonics is a technology that enables non-contact ultrasonic measurements, using lasers to generate and detect ultrasound pulses. Unlike other ultrasonic technologies, it can be used on hot materials because there is no physical contact. Therefore, it is ideally suited for in-situ studies of solid metallic materials up to their melting point.
How It Works:
The LUMet system generates and detects ultrasound pulses in a sample. To generate the ultrasound pulse in the sample, a high-power, shortpulse laser produces light pulses about 10 nanoseconds in duration. Each pulse causes intense pressure on the surface of the sample and sends an ultrasonic pressure pulse through it.
A laser interferometer measures sub-nanometer surface displacement caused by the pulse laser and its subsequent reflections as it echoes through the sample with sub-nanometer resolution. Based on the measured velocity and attenuation of sound in the medium, researchers can determine texture, modulus, grain size and phase mixtures.
If you would like more information on the LUMet system, please take advantage of the following resources:
At the bottom of this e-mail we have included the titles and abstracts of a small sample of papers related to laser ultrasonics as a measurement tool for metallurgy
Join us here at DSI at the end of August for a live demonstration of the LUMet in action. Contact our team to schedule your visit. (info@Gleeble.com)
Digital Image Correlation (DIC) can be used in conjunction with Gleeble Systems for 3D non-contact optical measurements of deformation and strain. DSI has developed a successful combination of high performance cameras, lighting, mounting and licensed software to produce accurate results, even at elevated temperatures (over 1,100˚C).
Digital Image Correlation can be utilized on a number of standard Gleeble tests including tensile tests, Strain Induced Crack Opening (SICO), flow stress compression, as well as other standard and custom simulations.
DSI collaborates with the world's leading DIC providers to supply, install and support complete DIC systems. Additionally, DSI can integrate most existing DIC hardware that may have been purchased for other purposes with with new or existing Gleeble Systems.
Please contact David "Jake" Jacon in our Parts and Service Group for more information. (Jake@Gleeble.com)
Save the Dates:Get your passports ready! This coming year offers a variety of opportunities for professional development and networking.
Thousands of papers have been published over the years that reference data collected using Gleeble simulation equipment. The following are several abstracts from these papers. Due to copyright regulations, we may not be able to share the full paper with our readers. However, these papers are typically available via website databases such as www.sciencedirect.com or www.scientific.net (fees may apply). Additional abstracts and papers can be found using common search tools such as www.scholar.google.com. In-situ laser ultrasonic grain size measurement in superalloy INCONEL 718 ThomasGarcin(a), Jean HubertSchmitt(b). Matthias Militzer(a)
(a) The Centre for Metallurgical Process Engineering, The University of British Columbia
(b) MSSMat, CNRS, CentraleSupélec, Université Paris-Saclay
Abstract:
The nickel-base superalloy, Inconel 718, is widely used in aircraft engines. The control of its final microstructure requires detailed knowledge on recrystallization, grain growth and second phase evolution during thermomechanical processing. The present study focuses on the in-situ evaluation of heterogeneous grain growth in the super-δ-solvus domain (above 1050 °C) using laser ultrasonics. This technology is dedicated to the ultrasonic characterization of microstructure evolution during thermomechanical processing of metals and alloys. The real time measurement of the ultrasonic attenuation provides the evolution of a representative grain size in the material. A criterion is developed to determine the onset and completion of heterogeneous grain growth stages associated with the dissolution of precipitates. The laser ultrasonic methodology is validated with ex-situ metallographic observations and quantitative characterization of the grain size heterogeneity. In-situ laser ultrasonic measurement of the hcp to bcc transformation in commercially pure titanium A.Shinbine, T.Garcin, C.Sinclair, Department of Materials Engineering, The University of British Columbia
Abstract:
Using a novel in-situ laser ultrasonic technique, the evolution of longitudinal velocity was used to measure the α − β transformation during cyclic heating and cooling in commercially pure titanium. In order to quantify the transformation kinetics, it is shown that changes in texture can not be ignored. This is particularly important in the case of titanium where significant grain growth occurs in the β-phase leading to the ultrasonic wave sampling a decreasing number of grains on each thermal treatment cycle. Electron backscatter diffraction measurements made postmortem in the region where the ultrasonic pulse traveled were used to obtain an estimate of such local texture and grain size changes. An analysis technique for including the anisotropy of wave velocity depending on local texture is presented and shown to give self consistent results for the transformation kinetics. Laser–ultrasonic absorption measurements in low carbon steels A. Moreau, M. Lord, D. Le´vesque, M. Dubois1, J.F. Bussie`re,
Institut des Mate´riaux Industriels
Abstract:
We have refined the contactless laser–ultrasound reverberation technique to measure ultrasonic absorption on small metallic samples. In this technique, a sample is supported by a holder which is ultrasonically decoupled from the sample. A pulsed laser is used to generate an acoustic pulse. After the pulse has mode converted and scattered sufficiently to fully insonify the sample, the decrease in the noise-like ultrasonic signal is recorded as a function of time using a laser-interferometer. A joint time–frequency analysis technique is used to extract an absorption spectrum from the signal. In this paper, the technique is demonstrated in a frequency bandwidth ranging from 1 to 7 21 MHz, and in a dynamic range of 0.003 to 0.3 dB ms . Measurements made on samples of three low-carbon steel grades, namely ultra low carbon (ULC), low carbon (LC), and high strength, low-alloy steels (HSLA), clearly show that ultrasonic absorption varies with steel grade. The technique was utilized to study the effect of a magnetic field on the ultrasonic absorption of an annealed ultra low carbon steel sample. It was found that magnetoelastic effects are responsible for a large fraction of the total absorption. Laser ultrasonic diagnostics of residual stress Alexander Karabutov(a), Anton Devichensky(b), Alexander Ivochkin(a), Michael Lyamshev(b), Ivan Pelivanov(a), Upendra Rohadgi(c), Vladimir Solomatin(a), Manomohan Subudhi(c) (a) International Laser Center of Moscow State University, Vorobevy Gory, 119992 Moscow, Russian Federation (b) General Physics Institute of the Russian Academy of Sciences 38, Vavilov Street, 119991 Moscow, Russian Federation (c) Brookhaven National Laboratory, Upton, 11973-5000 New York, USA
Abstract:
Ultrasonic NDE is one of the most promising methods for non-destructive diagnostics of residual stresses. However the relative change of sound velocity, which is directly proportional to applied stress, is extremely small. An initial stress of 100 MPa produces the result of dV/V~10 ^-4. Therefore measurements must be performed with high precision.
The required accuracy can be achieved with laser-exited ultrasonic transients. Radiation from a Nd-YAG laser (pulse duration 7 ns, pulse energy 100 lJ) was absorbed by the surface of the sample. The exited ultrasonic transients resembled the form of laser pulses. A specially designed optoacoustic transducer was used both for the excitation and detecting of the ultrasonic pulses. The wide frequency band of the piezodetector made it possible to achieve the time-of-flight measurements with an accuracy of about 0.5 ns.
This technique was used for measuring of plane residual stress in welds and for in-depth testing of subsurface residual stresses in metals. Plane stress distribution for welded metallic plates of different thicknesses (2–8 mm) and the subsurface stress distribution for titanium and nickel alloys were obtained. The results of conventional testing are in good agreement with the laser ultrasonic method. Microstructure model for the heat-affected zone of X80 linepipe steel T. Garcin, M. Militzer, W. J. Poole & L. Collins, The University of British Columbia
Abstract:
An important aspect of the integrity of oil and gas pipelines is the heat-affected zone (HAZ) of girth welds where the microstructure of the as-hot rolled steel is altered with potentially adverse effects on the HAZ properties. Therefore, it is critical to evaluate the HAZ microstructure for different welding scenarios. Here, an integrated microstructure evolution model is proposed and applied to the HAZ of an X80 linepipe steel. The model considers dissolution of Nb-rich precipitates, austenite grain growth and austenite decomposition into ferrite and bainite. Microstructure maps showing the fraction of transformation products as a function of distance from the fusion line are obtained and used to compare the effect of different welding procedures on the HAZ microstructure.
Connect with DSI on LinkedIn: Many professionals use LinkedIn to build their networks and develop collaborations. Please consider following DSI's company page and joining the LinkedIn Group titled: "Gleeble Thermal Mechanical Simulators". You can do this by using the links below.
You can "Follow" DSI by clicking here or by logging in to LinkedIn and searching for our company, but please note there are several companies named "Dynamic Systems". Please be sure to follow the company titled "Dynamic Systems Inc (Gleeble)"
Please join the group titled "Gleeble Thermal Mechanical Simulators". Here you can post messages, see what's new in the Gleeble community and connect with other users.
