Arc voltage distribution properties as a function of melting current, electrode gap, and CO pressure during vacuum arc remelting

Vacuum arc remelting (VAR) is an industrial metallurgical process widely used throughout the specialty metals industry to cast large alloy ingots. The VAR process is carried out in a vacuum with the aim of melting a large consumable electrode (.4 m in diameter and 3000 kg in mass and larger) in such a way that that the resulting ingot has improved homogeneity. The VAR control problem consists of adjusting arc current to control electrode melt rate, which also depends on the electrode temperature distribution and adjusting electrode ram speed to control the arc gap between the electrode and the ingot. The process is governed by a 1 dimensional heat conduction partial differential equation with a moving boundary, which leads to an infinite dimensional, nonlinear system. In addition to the process nonlinearity, the inputs and all of the available measurements are corrupted with noise. In order to design a controller and a Kalman based estimator for this process, integral methods are used to derive a set of two coupled nonlinear ordinary differential equations in time, which capture the steady state and transient characteristics of melting in a VAR furnace. The model with the experimentally measured noise is then used to construct an estimator and a controller. The system can be described by two state variables that change in time: thermal boundary layer and melted length or alternatively electrode gap. The reduced order model compares favorably to an accurate finite difference model as well as melting data acquired for Ti-6Al-4V. It will be shown how this model can be used to obtain dynamic closed loop melt rate control while simultaneously controlling electrode gap. This controller and estimator were tested on a laboratory furnace at Timet.

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Macroscale Modeling of Multi-Physics Fields during Vacuum Arc Remelting of Ti-6Al-4V

Materials Science Forum ◽

10.4028/www.scientific.net/msf.789.603 ◽

2014 ◽

Vol 789 ◽

pp. 603-607

Author(s):

Bin Zhu ◽

Xiang Yi Xue ◽

Hong Chao Kou ◽

Cong Xiao ◽

Jin Shan Li

Keyword(s):

Temperature Field ◽

Molten Pool ◽

Element Model ◽

Melting Rate ◽

Vacuum Arc ◽

Physical Interaction ◽

Water Cooling ◽

Vacuum Arc Remelting ◽

Cooling Conditions ◽

Melting Current

A 3-D finite element model has been established using ANSYS12.0 software to simulate multi-physical interaction behavior during the Vacuum Arc Remelting (VAR) of 740-mm-diameter ingots of Ti-6Al-4V. The models of temperature field, electromagnetic and flow field were combined by progressive method. The effect of thermal contraction was considered in the simulation of temperature field and electromagnetic by setting a thin layer with different nature parameters at the ingot-crucible interface. The model results demonstrate the distributions of temperature, Lorenz force and flow velocity, and the influence of water cooling conditions, melting current and other process parameters. The molten pool behavior is mostly dominated by buoyancy force under circumstances in this case. The increase of the melting current results in an increase of the pool depth and melting rate, and causes great change of the molten pool profile, while the influence of the water cooling conditions is ignored.

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UDIMET 700

Alloy Digest ◽

10.31399/asm.ad.ni0051 ◽

1987 ◽

Vol 36 (1) ◽

Keyword(s):

Gas Turbines ◽

Base Alloy ◽

Heat Treating ◽

Vacuum Arc ◽

Vacuum Induction Melting ◽

Induction Melting ◽

Nickel Base Alloy ◽

Vacuum Arc Remelting ◽

Temperature Performance ◽

Nickel Base

Abstract UDIMET 700 is a wrought nickel-base alloy produced by vacuum-induction melting and further refined by vacuum-arc remelting. It has excellent mechanical properties at high temperatures. Among its applications are blades for aircraft, marine and land-based gas turbines and rotor discs. This datasheet provides information on composition, physical properties, elasticity, and tensile properties as well as creep. It also includes information on high temperature performance and corrosion resistance as well as forming, heat treating, machining, joining, and surface treatment. Filing Code: Ni-51. Producer or source: Special Metals Corporation. Originally published March 1959, revised January 1987.

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UDIMET 90

Alloy Digest ◽

10.31399/asm.ad.ni0174 ◽

1972 ◽

Vol 21 (6) ◽

Keyword(s):

Corrosion Resistance ◽

Base Alloy ◽

Heat Treating ◽

Vacuum Arc ◽

Vacuum Induction Melting ◽

Induction Melting ◽

Nickel Base Alloy ◽

Vacuum Arc Remelting ◽

Temperature Performance ◽

Nickel Base

Abstract UDIMET 90 is a nickel-base alloy developed for elevated-temperature service. It is produced by vacuum induction melting and vacuum arc remelting techniques to develop optimum properties. This datasheet provides information on composition, physical properties, elasticity, and tensile properties as well as creep. It also includes information on high temperature performance and corrosion resistance as well as forming, heat treating, machining, joining, and surface treatment. Filing Code: Ni-174. Producer or source: Special Metals Corporation.

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LESCALLOY 15-5 VAC-ARC

Alloy Digest ◽

10.31399/asm.ad.ss0522 ◽

1991 ◽

Vol 40 (8) ◽

Keyword(s):

Stainless Steel ◽

Precipitation Hardening ◽

Martensitic Stainless Steel ◽

Heat Treating ◽

Gas Content ◽

Vacuum Arc ◽

Steel Company ◽

Delta Ferrite ◽

Clean Steel ◽

Vacuum Arc Remelting

Abstract LESCALLOY 15-5 VAC-ARC is a precipitation hardening martensitic stainless steel with minimal delta ferrite. Vacuum arc remelting in the production of the alloy provides a low gas content, clean steel with optimum transverse properties. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on corrosion resistance as well as forming, heat treating, machining, and joining. Filing Code: SS-522. Producer or source: Latrobe Steel Company.

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VASCOMAX T-300

Alloy Digest ◽

10.31399/asm.ad.sa0454 ◽

1990 ◽

Vol 39 (12) ◽

Keyword(s):

Heat Treatment ◽

Fracture Toughness ◽

Tensile Strength ◽

High Temperature ◽

Heat Treating ◽

Vacuum Arc ◽

Vacuum Induction Melting ◽

Induction Melting ◽

Vacuum Arc Remelting ◽

Temperature Performance

Abstract VASCOMAX T-300 is an 18% nickel maraging steel in which titanium is the primary strengthening agent. It develops a tensile strength of about 300,000 psi with simple heat treatment. The alloy is produced by Vacuum Induction Melting/Vacuum Arc Remelting. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties as well as fracture toughness. It also includes information on high temperature performance as well as forming, heat treating, machining, and joining. Filing Code: SA-454. Producer or source: Teledyne Vasco.

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ALLVAC Ti-15Mo

Alloy Digest ◽

10.31399/asm.ad.ti0136 ◽

2005 ◽

Vol 54 (7) ◽

Keyword(s):

Vacuum Arc ◽

Unique Combination ◽

Vacuum Arc Remelting ◽

Beta Alloy ◽

Metastable Beta

Abstract Allvac Ti-15Mo is a metastable beta alloy melted in a vacuum arc remelting (VAR) furnace to minimize segregation. The alloy has a unique combination of properties and is used in the medical, chemical, and aerospace industries. This datasheet provides information on composition. Filing Code: TI-136. Producer or source: Allvac, an Allegheny Technologies Company.

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FINKL 420M PREMIUM QUALITY

Alloy Digest ◽

10.31399/asm.ad.ss0707 ◽

1998 ◽

Vol 47 (2) ◽

Keyword(s):

Stainless Steel ◽

Physical Properties ◽

Heat Treating ◽

Vacuum Arc ◽

Vacuum Arc Remelting ◽

Aisi 420

Abstract Finkl 420 Premium Quality stainless steel is a modification of AISI 420 with vacuum arc degassing and vacuum arc remelting. The modification results in a refined structure yielding cleanliness, strength, and isotropic properties. This datasheet provides information on composition, physical properties, and hardness. It also includes information on heat treating. Filing Code: SS-707. Producer or source: A. Finkl & Sons Company.

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