Optimization of Laser Hardening Processes for Industrial Parts With Complex Geometry via Predictive Modeling

2009 ◽  
Author(s):  
Neil S. Bailey ◽  
Yung C. Shin
Keyword(s):  
Phase Transformation ◽  
Thermal Model ◽  
Complex Geometry ◽  
Solid Phase ◽  
Three Dimensional ◽  
Laser Hardening ◽  
Temperature History ◽  
Temperature Phase ◽  
Laser Systems ◽  
History Of

A predictive laser hardening model for industrial parts with complex geometric features has been developed and used for optimization of hardening processes. A transient three-dimensional thermal model is combined with a three-dimensional kinetic model for steel phase transformation and solved in order to predict the temperature history and solid phase history of the workpiece while considering latent heat of phase transformation. Further, back-tempering is also added to the model to determine the phase transformation during multitrack laser hardening. The integrated model is designed to accurately predict temperature, phase distributions and hardness inside complex geometric domains. The laser hardening parameters for two industrial workpieces are optimized for two different industrial laser systems using this model. Experimental results confirm the validity of predicted results.

Modeling Phase Transformation Kinetics and Their Effect on Hardness and Hardness Depth in Laser Hardening of Hypoeutectoid Steel

2015 ◽  
Author(s):  
Suhash Ghosh ◽  
Chittaranjan Sahay
Keyword(s):  
Thermal Analysis ◽  
Phase Transformation ◽  
Phase Transformations ◽  
Laser Hardening ◽  
Temperature History ◽  
Transformation Kinetics ◽  
Continuous Cooling ◽  
Phase Transformation Kinetics ◽  
Hardness Depth ◽  
Hypoeutectoid Steel

Much research has been done to model laser hardening phase transformation kinetics. In that research, assumptions are made about the austenization of the steel that does not translate into accurate hardness depth calculations. The purpose of this paper is to develop an analytical method to accurately model laser hardening phase transformation kinetics of hypoeutectoid steel, accounting for non-homogeneous austenization. The modeling is split into two sections. The first models the transient thermal analysis to obtain temperature time-histories for each point in the workpiece. The second models non-homogeneous austenization and utilizes continuous cooling curves to predict microstructure and hardness. Non-homogeneous austenization plays a significant role in the hardness and hardness depth in the steel. A finite element based three-dimensional thermal analysis in ANSYS is performed to obtain the temperature history on three steel workpieces for laser hardening process with no melting; AISI 1030, 1040 and 1045 steels. This is followed by the determination of microstructural changes due to ferrite and pearlite transformation to austenite during heating and the subsequent austenite to martensite and other diffusional transformations during cooling. Johnson-Mehl-Avrami-Kolmogorov (JMAK) equation is used to track the phase transformations during heating, including the effects of non-homogenous austenitization. The solid state nodal phase transformations during cooling are monitored on the material’s digitized Continuous Cooling Transformation (CCT) curve through a user defined input file in ANSYS for all cooling rates within the Heat Affected Zone (HAZ). Material non-linearity is included in the model by including temperature dependent thermal properties for the material. The model predictions for hardness underneath the laser and the HAZ match well with the experimental results published in literature.

Self-Diffusion and Reorientation of Methylammonium Ions in (CH3NH3)2ZnCl4 Crystals as Studied by 1H-NMR

1989 ◽  
Vol 44 (8) ◽  
pp. 741-746 ◽  
Author(s):  
Hiroyuki Ishida ◽  
Tadashi Iwachido ◽  
Naomi Hayama ◽  
Ryuichi Ikeda ◽  
Mifune Terashima ◽  
...  
Keyword(s):  
Solid Phase ◽  
Relaxation Times ◽  
Three Dimensional ◽  
Lattice Relaxation ◽  
High Temperature Phase ◽  
Spin Lattice Relaxation ◽  
Temperature Phase ◽  
Scanning Calorimetry ◽  
Self Diffusion ◽  
H Nmr

Abstract Differential thermal analysis, differential scanning calorimetry, and measurements of the 1H spin-lattice relaxation times and second moments of 1H-NMR absorptions were performed on methylammonium tetrachlorozincate (II) crystals over a wide temperature range. A solid-solid phase transition was located at 477 K. From the 1H-NMR experiments it was found that the cations undergo overall reorientation as well as three dimensional translational self-diffusion in the high-temperature phase. In the low-temperature phase, a 120° reorientational motion of the CH3 and NH3+ groups of the cation about its C-N bond axis was detected. The parameters for the motional modes of the cations in the crystal were evaluated from the analysis of the 1H-NMR experimental results.

Numerical Simulation on Temperature History during Cooling Process of Wire Rod

2011 ◽  
Vol 337 ◽  
pp. 188-191
Author(s):  
Chao Chen ◽  
Cui Jiao Ding ◽  
De Gang Ouyang ◽  
Sheng Chen ◽  
Zhong Hua Song
Keyword(s):  
Numerical Simulation ◽  
Mathematical Model ◽  
Phase Transformation ◽  
Energy Balance ◽  
Temperature History ◽  
Cooling Process ◽  
Energy Balance Method ◽  
One Dimensional ◽  
Wire Rod ◽  
History Of

A one-dimensional mathematical model of wire rod during cooling was developed. This model considered the heat of phase transformation during the cooling process. Based on the energy-balance method the equations were calculated, and the temperature history during cooling process of wire rod was obtained. The comparison of the calculated results with the measured results showed that the model worked well for simulating the temperature history of wire rod during cooling process. The effects of roller speed, diameter of wire and fan delivery on temperature history of wire were analyzed. With this developed model, the optimizing of cooling processes of wire rod can be investigated in the future.

Effect of Ingress on Turbine Discs

2015 ◽  
Author(s):  
GeonHwan Cho ◽  
Carl M. Sangan ◽  
J. Michael Owen ◽  
Gary D. Lock
Keyword(s):  
Three Dimensional ◽  
Temperature History ◽  
Infrared Sensors ◽  
Rotating Disc ◽  
Hot Gas ◽  
Mainstream Flow ◽  
History Of ◽  
Thermal Buffering ◽  
Adiabatic Effectiveness ◽  
Semi Empirical

The ingress of hot gas through the rim seal of a gas turbine depends on the pressure difference between the mainstream flow in the turbine annulus and that in the wheel-space radially inward of the seal. This paper describes experimental measurements which quantify the effect of ingress on both the stator and rotor discs in a wheel-space pressurised by sealing flow. Infrared sensors were developed and calibrated to accurately measure the temperature history of the rotating disc surface during a transient experiment, leading to an adiabatic effectiveness. The performance of four generic (though engine-representative) single- and double-clearance seals was assessed in terms of the variation of adiabatic effectiveness with sealing flow rate. The measurements identify a so-called thermal buffering effect, where the boundary layer on the rotor protects the disc from the effects of ingress. It was shown that the effectiveness on the rotor was significantly higher than the equivalent stator effectiveness for all rim seals tested. Although the ingress through the rim seal is a consequence of an unsteady, three-dimensional flow field, and the cause-effect relationship between pressure and the sealing effectiveness is complex, the time-averaged experimental data is shown to be successfully predicted by relatively simple semi-empirical models, which are described in a separate paper. Of particular interest to the designer, significant ingress can enter the wheel-space before its effect is sensed by the rotor.

Effect of Ingress on Turbine Disks

2015 ◽  
Vol 138 (4) ◽  
Author(s):  
GeonHwan Cho ◽  
Carl M. Sangan ◽  
J. Michael Owen ◽  
Gary D. Lock
Keyword(s):  
Three Dimensional ◽  
Rotating Disk ◽  
Disk Surface ◽  
Temperature History ◽  
Ir Sensors ◽  
History Of ◽  
Turbine Disks ◽  
Thermal Buffering ◽  
Adiabatic Effectiveness ◽  
Semi Empirical

The ingress of hot gas through the rim seal of a gas turbine depends on the pressure difference between the mainstream flow in the turbine annulus and that in the wheel-space radially inward of the seal. This paper describes experimental measurements which quantify the effect of ingress on both the stator and rotor disks in a wheel-space pressurized by sealing flow. Infrared (IR) sensors were developed and calibrated to accurately measure the temperature history of the rotating disk surface during a transient experiment, leading to an adiabatic effectiveness. The performance of four generic (though engine-representative) single- and double-clearance seals was assessed in terms of the variation of adiabatic effectiveness with sealing flow rate. The measurements identify a so-called thermal buffering effect, where the boundary layer on the rotor protects the disk from the effects of ingress. It was shown that the effectiveness on the rotor was significantly higher than the equivalent stator effectiveness for all rim seals tested. Although the ingress through the rim seal is a consequence of an unsteady, three-dimensional flow field, and the cause–effect relationship between pressure and the sealing effectiveness is complex, the time-averaged experimental data are shown to be successfully predicted by relatively simple semi-empirical models, which are described in a separate paper. Of particular interest to the designer, significant ingress can enter the wheel-space before its effect is sensed by the rotor.

Apatite fission track analysis: geological thermal history analysis based on a three-dimensional random process of linear radiation damage

1990 ◽  
Vol 332 (1627) ◽  
pp. 419-438 ◽  
Keyword(s):  
Random Process ◽  
Three Dimensional ◽  
Temperature History ◽  
Apatite Crystal ◽  
Maximum Temperature ◽  
Geological Time ◽  
Full Likelihood ◽  
History Analysis ◽  
History Of ◽  
Uplift And Erosion

Spontaneous fission of uranium atoms over geological time creates a random process of linearly shaped features (fission tracks) inside an apatite crystal. The theoretical distributions associated with this process are governed by the elapsed time and temperature history, but other factors are also reflected in empirical measurements as consequences of sampling by plane section and chemical etching. These include geometrical biases leading to over-representation of long tracks, the shape and orientation of host features when sampling totally confined tracks, and ‘gaps’ in heavily annealed tracks. We study the estimation of geological parameters in the presence of these factors using measurements on both confined tracks and projected semi-tracks. Of particular interest is a history of sedimentation, uplift and erosion giving rise to a twocomponent mixture of tracks in which the parameters reflect the current temperature, the maximum temperature and the timing of uplift. A full likelihood analysis based on all measured densities, lengths and orientations is feasible, but because some geometrical biases and measurement limitations are only partly understood it seems preferable to use conditional likelihoods given numbers and orientations of confined tracks

scholarly journals Uncovering a reconstructive solid–solid phase transition in a metal–organic framework

2017 ◽  
Vol 4 (11) ◽  
pp. 171355 ◽  
Author(s):  
L. Longley ◽  
N. Li ◽  
F. Wei ◽  
T. D. Bennett
Keyword(s):  
Density Functional ◽  
Solid Phase ◽  
Metal Organic Framework ◽  
Three Dimensional ◽  
High Temperature Phase ◽  
Temperature Phase ◽  
Scanning Calorimetry ◽  
Young’S Moduli ◽  
Metal Organic ◽  
Organic Framework

A nanoporous three-dimensional metal–organic framework (MOF), ZnPurBr undergoes a transition to a previously unreported high-temperature phase, ZnPurBr-ht. The transition, which proceeds without mass loss, is uncovered through the use of differential scanning calorimetry (DSC). The new crystal structure was solved using single-crystal X-ray diffraction, and the mechanical properties of both phases investigated by nanoindentation and density functional theory. The anisotropy of the calculated Young's moduli showed good agreement with the crystallographic alignment of the stiff purinate organic linker. The results provide a prototypical example of the importance of the use of DSC in the MOF field, where its use is not currently standard in characterization.

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