Monitoring austenite decomposition by ultrasonic velocity

Kruger, S. E.; Damm, E. Buddy

doi:10.1016/j.msea.2006.03.056

Cited by 41 publications

(22 citation statements)

References 13 publications

(16 reference statements)

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“…These studies have been mainly focused on quantifying absorption and scattering of the ultrasonic wave as a function of frequency and grain size in carbon and low alloy steels. Recently, Krueger and Damm [9] have reported interesting velocity measurements using an ultrasonic technique for predicting austenite fraction during cooling of carbon steels. Such a method shows a great applicability in heat treatment assessments and could be extrapolated to phase transformation in more complex alloys.…”

Section: Introductionmentioning

confidence: 99%

Characterization of the sensitization degree in the AISI 304 stainless steel using spectral analysis and conventional ultrasonic techniques

Stella¹,

Cerezo²,

Rodríguez³

2009

NDT & E International

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Section: Introductionmentioning

confidence: 99%

Characterization of the sensitization degree in the AISI 304 stainless steel using spectral analysis and conventional ultrasonic techniques

Stella¹,

Cerezo²,

Rodríguez³

2009

NDT & E International

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“…The part temperatures, especially the core, cannot typically be sensed and measured while the part is being processed inside the furnace. Nevertheless, the temperatures of the parts after exiting the furnace can be measured by non-contact ultrasonic measurements [34][35][36]. In practice, the operators tend to overheat the parts such that a minimum temperature threshold is exceeded, thereby causing excess fuel consumption.…”

Section: Process and System Descriptionmentioning

confidence: 99%

“…The setpoint for the MPC controller is the part minimum temperature at exit of the furnace. Note that non-contact ultrasonic measurements can be used to measure the value of minimum part temperature at the exit of the furnace [34][35][36]. However, non-contact measurements of the part temperatures, while the part is being processed inside the furnace, would be inaccurate due to the interference of the ultrasonic signal with the furnace walls.…”

Section: Furnace Simulation Under Model Predictive Controlmentioning

confidence: 99%

Model Predictive Control of the Exit Part Temperature for an Austenitization Furnace

2016

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Quench hardening is the process of strengthening and hardening ferrous metals and alloys by heating the material to a specific temperature to form austenite (austenitization), followed by rapid cooling (quenching) in water, brine or oil to introduce a hardened phase called martensite. The material is then often tempered to increase toughness, as it may decrease from the quench hardening process. The austenitization process is highly energy-intensive and many of the industrial austenitization furnaces were built and equipped prior to the advent of advanced control strategies and thus use large, sub-optimal amounts of energy. The model computes the energy usage of the furnace and the part temperature profile as a function of time and position within the furnace under temperature feedback control. In this paper, the aforementioned model is used to simulate the furnace for a batch of forty parts under heuristic temperature set points suggested by the operators of the plant. A model predictive control (MPC) system is then developed and deployed to control the the part temperature at the furnace exit thereby preventing the parts from overheating. An energy efficiency gain of 5.3% was obtained under model predictive control compared to operation under heuristic temperature set points tracked by a regulatory control layer.

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“…Measurements of microstructure evolution can now be conducted remotely and in realtime on a sample during thermomechanical treatments. Grain growth, phase transformation and recrystallization processes were successfully monitored by the laser ultrasonic technique in a wide range of materials such as steel, aluminium and zirconium alloys [3][4][5][6][7][8][9][10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Application of laser ultrasonics to monitor microstructure evolution in Inconel 718 superalloy

Garcin

Schmitt

Militzer

2014

MATEC Web of Conferences

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Abstract. Laser ultrasonics for metallurgy is an innovative sensor dedicated to the measurement of microstructure evolution during thermomechanical processing. In this technique, broadband ultrasound pulses are generated and detected with lasers. The properties of the ultrasounds are then related to the characteristics of the microstructure. Ultrasound attenuation is primary originated by the scattering at grain boundaries and its frequency dependence can be related to the grain size. The present work aims to introduce this technology as an exciting tool for metallurgists. As an illustration of its capability, the evolution of the grain size during isothermal annealing from a fine grained structure is in-situ monitored in an Inconel 718 superalloy. Laser ultrasonic measurements are compared with ex-situ metallography observations. Indication of heterogeneous grain growth is observed, correlated to the dissolution of δ-phase particles present in the initial structure. This preliminary study illustrates the potential of this new technique to monitor microstructure evolution in more complex scenarios including recrystallization during simulation of hot forging processes.

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Monitoring austenite decomposition by ultrasonic velocity

Cited by 41 publications

References 13 publications

Characterization of the sensitization degree in the AISI 304 stainless steel using spectral analysis and conventional ultrasonic techniques

Characterization of the sensitization degree in the AISI 304 stainless steel using spectral analysis and conventional ultrasonic techniques

Model Predictive Control of the Exit Part Temperature for an Austenitization Furnace

Application of laser ultrasonics to monitor microstructure evolution in Inconel 718 superalloy

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