Mechanical Engineering
Materials Science & Engineering

Conferences 2005

ASM Heat Treating Society Conference and Exposition (September 26-28, 2005)

The conference held in Pittsburgh, PA was attended by Graduate Students: Shuhui Ma, Virendra Warke, Yao Zhou, Olly Karabelchtchikova, Radhakrishnan Purushothaman, Prof. Richard Sisson, Jr., Research Asst. Professor Md. Maniruzzaman

Papers presented:

Development of Quench Factor Analysis of Cast Al-Si-Mg Alloys

Authors:

S. Ma, Md. Maniruzzaman, and R. D. Sisson, Jr.

Abstract

The mechanical properties of age-hardenable Al-Si-Mg alloys, to a large extent, depend on the rate at which the alloy is cooled after the solutionizing treatment. Quench factor analysis was developed to describe the relationship between cooling rate and final mechanical properties of the age-hardenable materials. This analysis assumes the precipitation kinetics of aluminum alloys during continuous cooling is additive and can be described by the nucleation and growth kinetics of the secondary phase. This method has been previously used to successfully predict yield strength, hardness of wrought aluminum alloys. However, the quench factor data for aluminum castings is still rare in the literature. In this study, the Jominy end quench approach is used to develop Time-Temperature-Property curves for quench factor analysis of cast aluminum alloy A356. The results are discussed based on the precipitation kinetics and microstructure as a function of cooling rate along the length of the bar.

Optimization of Solution Treatment Process for Lost Foam Casting A356 Aluminum Alloy Engine Heads

Authors:

Md. Maniruzzaman, Y. Rong, WPI, R.D. Sisson, Jr., WPI, D. Caswell, Alfe Heat Treating, Defiance, OH, P.N. Crepeau, GM Powertrain, Pontiac, MI.

Abstract

A356 aluminum alloy engine cylinder heads were produced using lost foam casting process. To dissolve the nonequilibrium second phase, the heads were solution heat treated by holding at 1000oF in a batch furnace and then rapidly quenched in an agitated water tank. The cylinder head was instrumented using several thermocouples at some strategic locations to measure the time-temperature response during heating, holding and quenching. Effects of racking and solutionizing time were investigated and the results are presented in the paper. Based on the experimental findings, an optimum solution heat treatment process for aluminum alloy engine head is proposed.

Predicting Distortion and Residual Stress Due to Heat Treatment of Sintered Pourous Steel Parts

Authors:

V. Warke, R.D. Sisson, M.M. Makhlouf, WPI, B.L. Ferguson, Deformatin Control Technology, Inc., Cleveland, OH; Z.Li, Deformatin Control Technology, Inc., Cleveland, OH

Abstract

A major economic benefit of press and sinter P/M technology is net- and near-net shape capability. However, heat treatment of steel components introduces possible distortion due to nonuniform heating and cooling and volumetric changes associated with phase transformations. Unanticipated distortion can eliminate the economic benefit of this production method. Also, heat treatment introduces residual stress into the component which may adversely affect the fatigue resistance of the sintered porous component. This paper reports on work-in-progress at WPI to characterize the phase transformation kinetics of 4600 steel powder in terms of part porosity, and on joint work between WPI and DCT to simulate heat treatment of sintered porous parts using the finite element method. Simulation results will be presented to demonstrate the influence of sintered density gradients on residual stress and distortion for through-hardened porous 4650 steel part.

Computerized Heat Treating Planning Systems (CHT-bf) as an Effective Tool to assist the Heat Treating Industry

Authors:

R.S. Vaidya, L. Roether, American Heat Treating Inc., Monroe, CT

Abstract

A Computerized Heat Treating Planning System (CHT- bf) was developed by Center Of Heat Treatment and Excellence (CHTE), Worcester Polytechnic Institute, Worcester, MA to assist the heat treatment process. The CHT- bf is an analytical tool for the calculation of the load temperature as well as the thermal schedule. Two case studies were carried out by American Heat Treating Inc Monroe, CT the first case study was carried out to increase the number of workpieces going in the furnace. The second case study was to predict the thermal schedule and the load pattern of a totally new job. Thus further assisting American Heat Treating Inc. in quotation process and thereby winning a new part order for processing.

Modeling Carburization Heat Treatments

Authors:

R.D. Sisson, Jr., O. Karabelchtchikova, Md. Maniruzzaman

Abstract

Carburization heat treatment modeling will be reviewed. The data base needs will be discussed in terms of availability and accuracy requirements. The impact of inaccurate diffusivieties and surface mass transfer coefficients will be presented in terms of carbon profiles and case depths. The relationships among the process parameters and the property specifications will also be presented.

Effects of Surface Oxides on the Quenching Behavior of 4140 Steel in Commercial Mineral Oils

Authors:

S. Ma., Md. Maniruzzaman, Juan Chaves and R. D. Sisson, Jr.

Abstract

The effect of oxide formation on the cooling rate and heat transfer coefficient as a function of temperature of 4140 steel probes has been experimentally and numerically investigated using the CHTE Quench Probe System. Time-temperature data has been collected for 4140 probes oxidized in air for 0, 5, 20 and 80 minutes oxidation times and then quenched in mineral oil-Houghton G. The heat transfer coefficient as a function of temperature has been estimated using inverse calculation by steepest descent method. The results indicate that a thin layer of oxides on the probe surface enhances the cooling rate by providing more nucleation sites for the bubble formation. However, when the oxidization time is prolonged to 20 and 80 minutes, the insulating effect is found more prominent, which is due to the low conductivity of iron oxides and the calculated heat transfer coefficient decreases.

The Effect of Flow Rate and Droplet Distribution on Spray Quenching Performance of 4140 Steel and IVF Probe in Water

Authors:

Lin Lee, Md. Maniruzzaman, Richard D. Sisson, Jr.

Abstract

An experimental investigation has been conducted on the 4140 steel and IVF quench probe to quantify the influence of water flow rate and droplet distribution on the cooling rate and heat transfer coefficient. Time-temperature data has been collected for each spraying condition by using spray quenching system. Heat transfer coefficients as a function of temperature have been estimated using lumped parameter analysis. The results from this study indicate that the heat transfer coefficient of spray quenching is higher than that of the traditional immersion quenching. It is also found the cooling rate decreases with the decrease in the flow rate. Slight variation is seen in the influence of droplet distribution at high flow rate.

Computational simulation of high pressure gas quenching process

Authors:

Md. Maniruzzaman and R.D. Sisson, Jr.

Abstract

Quenching heat treatment process in a high pressure gas quenching chamber is simulated using a Computational Fluid Dynamics (CFD) simulation software. Gas flow field inside the chamber during cooling is studied and the surface heat transfer coefficients of the quenched part as a function of temperature are computed. The effect of gas flow rate on the quenching behavior of the quench parts are also evaluated. The computational results are verified using experimentally acquired time-temperature history of the quenched parts.

Integrated Numerical Simulation and Process Optimization for Aluminum Alloy Solutionizing

Authors:

Y. Zhou, J. Kang, and Y. Rong
Worcester Polytechnic Institute

F. Yi, Y. Ma, J. Fang, H. Brody
University of Connecticut

Abstract

Solutionizing treatment of aluminum alloy is a time consuming process. Due to the lack of quantitative process model, thermal schedules are still designed based on experience in current industry and are usually very conservative.

An integrated software tool has been developed for numerical modeling and simulation of aluminum alloy solutionizing processes. It includes three modules, thermal analysis, alloy microstructure analysis, and mechanical property prediction. The thermal analysis module predicts the temperature distribution history of the entire furnace-load system with user-specified furnace and load conditions and thermal schedule, using Finite Difference Method (FDM). Subsequent simulations are carried out based on the results of thermal prediction and as-cast condition of the alloy. On one hand, microstructure analysis module predicts the variation of phase composition during the heat treatment process; while on the other, the property prediction module predicts the mechanical properties achieved from the process. The results from the simulation and analysis can be used to design the alloy and heat treatment processes with predictable properties, as well as to optimize the heat treatment process with ensured quality and short cycle time. A case study was carried out and the cycle time was significantly reduced.

An integrated software tool has been developed for numerical modeling and simulation of aluminum alloy solutionizing processes. The model integrates thermal analysis, alloy microstructure analysis and mechanical property prediction. The simulation and analysis can be used to design heat treatment processes to achieve predictable properties of alloys, as well as to reduce process cycle time and energy consumption.

Industrial Application of CHT-bf and CHT-cf

Authors:

Jinwu Kang, Radhakrishnan Purushothaman and Yiming Rong

Abstract

CHT-bf/cf, Computerized Heat Treating Planning System for batch furnaces and continuous furnaces, is aiming at the optimization of heat treating process by the evaluation thermal schedule and load pattern of part as the part load and furnace are selected. The software integrates convection, radiation and conduction heat transfer methods, the model of furnaces and database. It has been validated by almost twenty case studies and now is widely applied in the focus group members of Center for Heat Treating Excellence. Here several successful stories about the application of the software are presented. The results show about 20 percent energy and time are saved through the optimization by this software.

Estimating Heat Transfer Coefficients as a Function of Temperature by Data Mining

Authors:

Aparna Varde, Elke Rundensteiner, Mohammed Maniruzzaman and Richard D. Sisson Jr.

Abstract

Data Mining consists of finding interesting patterns in large datasets to guide decisions. This paper describes a technique "AutoDomainMine" that performs data mining guided by basic domain knowledge to discover more advanced knowledge. The data being mined comes primarily from heat treating experiments. It involves input conditions of quenching experiments and the resulting graphs, namely, heat transfer curves which are a plot of heat transfer coefficients versus part temperature. Since heat transfer coefficients characterize quenching experiments, estimating a heat transfer curve given the input conditions assists in decision-making. For instance, the estimated curves could serve as the input to simulation tools for analysis. The AutoDomainMine approach integrates two data mining techniques clustering and classification into a learning strategy. It first clusters graphical results of existing experiments, i.e., heat transfer curves, and then uses classification to learn the clustering criteria, i.e., input conditions characterizing the clusters. The learned criteria are used to design cluster representatives that help to classify unseen data. These serve as the basis for estimating the results of new experiments given the input conditions. The AutoDomainMine approach gives higher accuracy than state-of-the-art techniques such as similarity searching. It is being further enhanced by distance metric learning to capture the semantics of graphs and by designing domain-specific cluster representatives as better classifiers for estimation.

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