Integrated modeling for the manufacture of aerospace discs: Grain structure evolution

Kermanpur, A.; Tin, Sammy; Lee, Peter; McLean, M.

doi:10.1007/s11837-004-0040-7

Cited by 23 publications

(16 citation statements)

References 15 publications

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“…One way of doing this is to adopt a through process modeling methodology linking the microstructural features and defects to the local stress state arising from both residual stresses and in-service cyclic loads. Although this concept has been proposed previously by the current authors [4,6,7] and others, [8] these prior studies have not determined the sensitivity of the final fatigue life of A356 components to the accuracy of the residual stress calculations, nor were these calculations validated. This article will focus on these aspects.…”

Section: Introductionmentioning

confidence: 99%

Simulating the Residual Stress in an A356 Automotive Wheel and Its Impact on Fatigue Life

Maijer

Lindley

et al. 2007

Metall Mater Trans B

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Keeping the weight of unsprung rotating components low is critical for fuel efficiency in automobiles; therefore, cast aluminum alloys are the current material of choice for wheels. However, pores formed during solidification can combine with residual stresses and in-service loads to reduce the fatigue life of this safety critical part. In this study, a model of the residual stresses arising from the quench stage of a T6 heat treatment was developed. The resulting predictions were compared to residual strain measurements made on quenched wheels via a strain gage/sectioning technique. The predictions were shown to be sensitive to the alloy's flow stress behavior, yet no data were available for the temperature-dependent and strain-rate-dependent inelastic behavior of A356 in the as-solutionized condition. Measurements of this behavior were made using a GLEEBLE 3500, and the data were incorporated into the model, significantly improving the correlation between model and experiment. In order to determine the influence of residual stress upon the final fatigue performance of the wheel during service, the change in stress level due to machining was first calculated. The residual stress was then compounded together with a service stress to determine the local stress at all points in the wheel during idealized operation. Finally, the fatigue behavior was predicted using a unified initiation and propagation model based on this local stress and an idealized pore size.

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Section: Introductionmentioning

confidence: 99%

Simulating the Residual Stress in an A356 Automotive Wheel and Its Impact on Fatigue Life

Maijer

Lindley

et al. 2007

Metall Mater Trans B

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“…[27][28][29][30] Details of the multiscale model have been described elsewhere. [3,11] In the macromodel, input power, defined as the power supply current multiplied by the machine voltage measured at the buss bars (P total ϭ I b V b ) is automatically balanced against several sources of energy dissipation. This total power is considered to be the sum of the power required to raise the metal to its superheat temperature, the thermal energy lost directly to the crucible wall, and the thermal energy transmitted to the top surface of the pool by the arc.…”

Section: Vacuum-arc Remeltingmentioning

confidence: 99%

“…[3] First, vacuum induction melting (VIM) is used to produce an alloyed electrode ingot with tightly controlled composition and low impurity levels. With the resulting properties of these structural materials being highly sensitive to trace elements (such as O, N, S, and C) melting in vacuum assists in minimizing contamination of cast ingots, which often weigh in excess of 5000 kg.…”

Section: Introductionmentioning

confidence: 99%

Integrated modeling for the manufacture of Ni-based superalloy discs from solidification to final heat treatment

Tin

Lee

Kermanpur

et al. 2005

Metall Mater Trans A

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Process models of the various stages of gas-turbine disc manufacture have been integrated to simulate the physical and microstructural transformations occurring within a nickel-based superalloy throughout the entire manufacturing route. Production of these critical rotating structural components requires several distinct processing stages: vacuum-induction melting (VIM), vacuum-arc remelting (VAR), homogenization heat treatment, cogging, forging, final heat treatment, and machining. During the course of these consecutive manufacturing stages, the various thermal and thermomechanical processes lead to significant changes in both the microstructural characteristics and internal stresses in the alloy. Although separate models have previously been developed to simulate the individual processing stages, this article describes how these models, which are explicitly expressed in terms of the initial and evolving microstructure, can be integrated to simulate the entire manufacturing process from secondary melting through to the final forging and heat treatment. The grain structure predicted for one stage is explicitly transferred as the initial conditions for the model, which simulates the grain evolution during the next step. This information also provides the basis of microstructure-explicit constitutive equations describing the material behavior. Industrial-scale manufacturing trials associated with the production of an INCONEL alloy 718 aeroengine turbine disc were used to validate the integrated model for grain size. The model also allows intrinsic or extrinsic defects entrained within the material during the initial solidification stage to be tracked through the subsequent processes. This provides a basis for calculating the areas of discs likely to be vulnerable to such defects and whether they might be removed during machining. It was shown that the microstructure of the alloy changes significantly throughout the process chain, the final microstructure and defect distribution at each stage being related to those formed in the previous stages. There was good agreement between the model predictions and experimental observations for both the intermediate and final processing stages. The implications of such integrated modeling for quality assurance through process control are discussed.

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“…In the area of Ni-based superalloys, the program for IMMAD is tasked with tracking defect, microstructure, and residual stress evolution through the five manufacturing stages for turbine disks. [8] In North America, the CTMP project for enhanced manufacturing of tubes and pipes has developed a through-process model of steel tube manufacturing to optimize product performance via novel thermo-mechanical processing routes. In each of these projects, linking the outputs of each process model into an overall through-process model is a significant challenge.…”

Section: A Through-process Modelingmentioning

confidence: 99%

A through-process model of an A356 brake caliper for fatigue life prediction

Maijer

Gao

Lee

et al. 2004

Metall Mater Trans A

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The demand for low-cost, high strength-to-weight ratio components continues to drive the development of aluminum alloy castings for new applications. The automotive brake caliper, which has traditionally been made from cast iron, is one such component where aluminum alloys are being considered. The fatigue performance of the brake caliper is an important consideration in evaluating new designs. The use of aluminum alloys in cast components under cyclic loading conditions necessitates a design approach that, in addition to in-service loading, incorporates the impact of microstructural features on fatigue life. In this investigation, a through-process modeling approach has been employed to link a series of mathematical models describing the processing steps of (1) casting, (2) heat treatment, (3) machining, and (4) in-service performance for a preliminary design of a brake caliper made of aluminum alloy A356.Step (1) includes microstructural predictions (secondary dendrite arm spacing and maximum pore size), which are tracked through to the final component. The final lifing of the component combines the effects of these microstructural features with the complex stress state arising from the combined service loading and residual stresses. It was found that all three factors have a strong influence upon the component's fatigue performance.

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Integrated modeling for the manufacture of aerospace discs: Grain structure evolution

Cited by 23 publications

References 15 publications

Simulating the Residual Stress in an A356 Automotive Wheel and Its Impact on Fatigue Life

Simulating the Residual Stress in an A356 Automotive Wheel and Its Impact on Fatigue Life

Integrated modeling for the manufacture of Ni-based superalloy discs from solidification to final heat treatment

A through-process model of an A356 brake caliper for fatigue life prediction

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