Microstructural evolution of Inconel* 718 during ingot breakdown: process modelling and validation

Dandre, C.A.; Roberts, S.M.; Evans, R. W.; Reed, Roger C.

doi:10.1179/026708300773002627

Cited by 53 publications

(28 citation statements)

References 12 publications

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“…Unique sets of constants (a, A, n', Q,,@ , B, m and Q3 are required for each of the points corresponding to o,, cr,, cr3 and a, [14]. A comprehensive compression testing programme was devised which considered a range of temperatures (950-115O'C) and strain-rates (0.001-10s") to derive these constants.…”

Section: The Process Modelmentioning

confidence: 99%

Microstructural Evolution of Nickel-Base Superalloy Forgings during Ingot-to-Billet Conversion: Process Modeling and Validation

Dandre¹,

Walsh²,

Evans³

et al. 2000

Superalloys 2000 (Ninth International Symposium)

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A computer-based process modelling capability has been developed to simulate the evolution of microstructure during ingot-to-billet conversion of nickel-base superalloys. A unique feature of the model is the incorporation of rules describing the dynamic and static recrystallisation phenomena that govern microstructural development. Computational investigations consider the influence of process control parameters such as die velocity and displacement to obtain an optimal microstructure. Furthermore, a comparison is made of the effective strain profiles obtained by squeezing flat versus rounded sections of the workpiece.The details of the model are given with particular emphasis placed on the description of microstructural evolution. A comprehensive testing programme using a purpose built compression testing machine has been carried out to acquire the materials data required for the model. The analysis of the flow curves is described. The microstructural model has been implemented within the three-dimensional visco-plastic Forge3"t finite element software. In order to validate the methodology developed, interrupted cogging trials have been performed. The evolution of microstructure is explained in terms of the cogging model and a more optimal process procedure suggested.Nickel-base superallovs for disc annlications

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Section: The Process Modelmentioning

confidence: 99%

Microstructural Evolution of Nickel-Base Superalloy Forgings during Ingot-to-Billet Conversion: Process Modeling and Validation

Dandre¹,

Walsh²,

Evans³

et al. 2000

Superalloys 2000 (Ninth International Symposium)

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“…To obtain the fine grain disks, it is necessary to refine the grains of the billets of which the disks are made by means of die forging. But it is difficult to refine the grains of large section size billets, especially at center position (1,2).…”

Section: Introductionmentioning

confidence: 99%

“…Alloy 718 billets have been generally forged by 2-ram press or 4-ram mechanical radial forging machine (GFM) (1)(2)(3)(4)(5)(6)(7)(8). In this study, 4-ram hydraulic radial forging machine, called SMX (by SMS EUMUCO Inc.), was used to forge Alloy 718 billets.…”

Section: Introductionmentioning

confidence: 99%

Grain Size Prediction of Alloy 718 Billet Forged by Radial Forging Machine Using Numerical and Physical Simulation

Kubota¹,

Ohno²,

Nonomura³

et al. 2001

Superalloys 718, 625, 706 and Various Derivatives (2001)

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Fine grains are required for Alloy 718 to obtain its high strength. Since grain size is strongly affected by forging conditions, many trial forgings are generally needed. On the other hand. grain size predictions by several simulations have been tried to reduce trial forgings. The purpose of this study is to predict grain size of Alloy 718 by combining a numerical simulation and a physical simulation. Firstly the transitions of temperature and strain of the forged material during hot forging were calculated by the 3-dimensional FEM. Secondly multi-stage plane strain compression tests using small test pieces were carried out by means of the Gleeble system according to the temperature and strain programs obtained by the numerical simulation, then the grain size was observed. These simulations were applied for predicting and refining the grain size of Alloy 718 billet forged by hydraulic 4-ram radial forging machine. Introduction Fine grains are required for Alloy 718 disks mainly used for gas turbines to obtain its high strength. To obtain the fine grain disks, it is necessary to refine the grains of the billets of which the disks are made by means of die forging. But it is difficult to refine the grains of large section size billets, especially at center position (1,2).Alloy 718 billets have been generally forged by 2-ram press or 4-ram mechanical radial forging machine (GFM) (1-8). In this study, 4-ram hydraulic radial forging machine, called SMX (by SMS EUMUCO Inc.), was used to forge Alloy 718 billets. SMX has advantages over the 2-ram press; its forging speed is higher and straighter and more truly round billet can be obtained. SMX also has advantages over GFM. The maximum load can be added throughout the full stroke by SMX whereas it can be added near the only bottom dead point by GFM. So the reduction in pass of SMX can be controlled, although that of GFM must be set a small value. Therefore SMX can easily control the forging conditions. These advantages are effective to obtain fine grains of all the regions of large section size billets.On the other hand, since grain size is strongly affected by the forging conditions, many trial forgings, which are very expensive especially for the high price materials such as Ni base superalloys and take much time, are generally needed to control the microstructure. Therefore grain size predictions by several simulations have been tried to reduce trial forgings (1,2:4-8). FEM (Finite Element Method) has been used to predict the strain and the temperature distribution and the microstructure including the grain size of forged products. Not only 2-dimensional FEM but also 3-dimensional FEM must be used for the forging by 2-ram press and 4-ram press, because the deformation behavior of these forgings is complicated. But grain size predictions only by FEM or other equations are difficult for highly-alloyed metals, because the grain growth and recrystallization behavior is very complicated. Especially, the grain sizes of Alloy 718 are strongly affected by the precipita...

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“…C.A. DANDRE and col. [2] or B. ANTOLOVICH and M. EVANS [3] have studied bar cogging on alloy 718, but phenomenon involved in multi-pass processes have not been studied in detail. Moreover, they still use Avrami formulation although this approach considers that the initial microstructure is fully recrystallized.…”

Section: Introduction: State Of Art In Microstructure Predictionmentioning

confidence: 99%

Microstructure Prediction during Incremental Processes for Hot Forming of 718 Alloy

Dumont

Georges

2011

AMR

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Abstract. Main works on microstructure prediction on superalloys during hot forming processes deal with close die forging of 718 alloy. In this paper, we focused our interest towards incremental hot forming process. In that case, matters become more complex, due to the partially recrystallized microstructure we have to take into account at the beginning of each pass. An original method is presented in this paper, still using a phenomenological approach, according to Avrami formulation, with two main additional assumptions, in order to carry out computation on microstructure evolution during the process. Examples with comparisons between real and computed microstructure (recristallyzed fraction, different populations of grain size) enable us to valid our model for bar forging.

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Microstructural evolution of Inconel* 718 during ingot breakdown: process modelling and validation

Cited by 53 publications

References 12 publications

Microstructural Evolution of Nickel-Base Superalloy Forgings during Ingot-to-Billet Conversion: Process Modeling and Validation

Microstructural Evolution of Nickel-Base Superalloy Forgings during Ingot-to-Billet Conversion: Process Modeling and Validation

Grain Size Prediction of Alloy 718 Billet Forged by Radial Forging Machine Using Numerical and Physical Simulation

Microstructure Prediction during Incremental Processes for Hot Forming of 718 Alloy

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