ISiJ International, Vol. 32 (1 992). No. 5, pp. 673-681

Review

Electron BeamMelting and Ref ining ot Metals and Alloys

Alok CHOUDHURYand Eckart HENGSBERGERMetallurglcal Department. LEYBOLDDURFERRITGmbH,Rueckinger StraBe 12, D-6455 Erlensee. Germany.

(Received on December10. 199l, accepted in final form on February 28. l992)

The increasing need for improved refractory and reactive high strength materials has led to the developmentof special production processes. This article will consider electron beammelting and refining which is

playing an important role especiaily in the production of nickel base superalloys, specialty steels, refractorymetals such as tantalum, niobium, tungsten, andmolybdenumand reactive metals such as hafnium, vanadium,zirconium, and titanium and their alloys. Thedrip and cold hearth melting and refining techniques includingthe electron beamheat sources are described. Process data and results for various materials are given.

KEYWORDS:electron beam; EB-drip melting; EB-cold hearth remelting; EB-button melting; refractory andreactive m9tals; superalloy.

l. IntroductionVolatile elements contained in the material or performedduring the melting process under vacuumby distillation

Increasing requirements for refractory and reactive or degassing. In addition to these cleaning effects, positivehigh strength materials suitable for use at high tem- conditions for the cast product structure (segregation,peratures in an aggressive atmosphere, ultra-pure ma- porosity, etc.) can be achieved, because electron beamterials typically required for, e.g., sputter targets and melting is a surface heating method, producing only anew alloys, have led to the development of special shallow pool.production processes in order to ensure metal products To fulfil the specific melting and refining requirements,of the most exact composition, required grain-structure several processes like drip melting, floating zone melting,and highest purity. cold hearth (continuous flow) melting andbutton melting

Oneof these production processes is electron beam have been developed, using very flexible electron beam(EB) melting and refining, introduced morethan 30 years heat sources. Someadvantages and limitations of the

ago. EBmelting and refining is playing an increasingly competing processes like sintering and vacuum arcimportant role in the production of nickel-base super- remelting are given in Table 1.1)

alloys, specialty steels, refractory metals like tantalum,niobium, very pure tungsten and molybdenum,especial-ly for the electronic industry, and reactive metals like

2. Electron BeamMelting Characteristics

hafnium, vanadium, zirconium, and titanium including Electron beammelting and refining technology is

their alloys. characterized by the following main features:Purification of the material is doneby the removal of - Melting in a wide vacuum range (10~4-10Pa) in

Tabte l. comparison of characteristics of electron beammehingand competing processes.

rll si*,.,i*g lrl~1 v...** ~.1*i*g rlr El~ b"* *'1'i*g --'-~bt,tal Ad****g* L,~,*'~~ Ad*~ta~ Li*i*ti.*=Ad**tag* Li*i*,i..=

Tungsten,mo]ybdenum

.

Tantalum.

Hafnium.

niobium..

Yanadium

Zirconium, titanium. .

Small grain size:

mosl often used

Small grain size:

good workability

Refining limited;

small batches;high energyconsDmption

Sameas above;rarely applied

Sameas above

Not used

MoJerate grain size:

acceptable workability:large ingots; Iow energyconsumption

Alloying: moderate grainsize: Iarge ingots: Iowenergy consumption

Alloying during remelting

Very low contamination;wide range of alloyingpossible: Iarge ingots:

low energy consumption:economical melting

Rer]ning limited:costly electrodepreparation ; meltingdangerous

Refining limited:

expensive electrode;melting dangerous

Almost no refining;

costly electrodepreparation: meltingdangerous

Limited refining:

expensive feedstockpreparation: onlyround ingots

Highest possibie purity;economical feedstockpreparation; Iargeingots: Iow energyconsumption

Sameas above: mostfrequently used

Goodrefining:

eeonomical feedstockpreparation and ingotproduction: mostoften used

Economical feedstockpreparation : refiningof high-densityinclusions: melting ofslabs, ingots, androds; high productionrate; Iow energyconsumption

Large grain size;

brittle product:

very rarely applied

Alloying limited

High mehingcosts

Alloying iimited;

material lossesfrom 5platter; high

fumace investment

673 C 1992 ISIJ

ISIJ International. Vol. 32 (1992), No. 5

~)

c

G

D

I~l;'

Fig. l. Principles of electron beammelting.

(A) Bottom melting for determination of nonmetallic inclusions, (B) Consolidation of raw material to

remelting electrodes, (C) Dripmelt of horizontally and vertically fed feedstock material, (D) Continuousflow or cold hearth refining melting, (E) Floating zone melting, (F) Investment casting, (G) Manufacturingof pellets from scrap for investment casting, (H) Atomizing/granulating of refractory/reactive metals.

a ceramic-free, water-cooled copper trough (cold

hearth melting) or crucible free to avoid any con-tamination

- High flexibility of melting rate and conditions for

removal of volatile trace elements

- Nearly unlimited melting temperature

- High power density (l03-l06W/cm2) avallable for

local superheating

- Favorable conditions, especially in a cold hearth, to

removelow density as well as high density inclusions

Goodcontrol of ingot solidification for desired pri-

mary structure

- Production of highest quality ingots of various size,

shape and quantity

High fiexibility in size, shape and quality of the

feedstock material

- Automation of the process.Figure I shows examples of the application of the

electron beammelting methods. In all these processes,high performance EBguns of the Pierce-type are the keycomponents. These EBguns are characterized by the

following main features:

- Broad power range of Oto 1200kW- Optimumbeamflexibility; deflection angle ~45', spot

frequency up to I OOOHz- Long free beampath of 250 to 1500mm.

Separate pumpingof the beamgeneration system andthe pre-focussing chamberallows melting in the pressure

range of l0~4 to lOPa in the melt chamber.2)

Figure 2showsa cross section of such a modernhigh

power EB gun. In combination with adequate highvoltage powersupplies with thyristor-controlled rectifier

units (SCR)guaranteeing low output tripple voltages for

sharp beamfocussing and a versatile EB-control system(Fig. 3) very accurate beampowerandenergy distribution

C 1992 ISIJ 674

can be achieved, thus allowing the required heating for

meterial melting, superheating, refining and electro-

thermal effects.

3. Melting Technique-State of the Art

The electron beammelting process is applied world-wide to melt and cast ductile refractory metal ingots

of niobium, tantalum, and hafnium. Superclean tung-sten and molybdenumfor the electronic industry aswell as vanadiumof high purity are also produced using

EB furnaces, Nickel-base superalloys are refined andtitanium scrap is recycled to produce not only ingots butalso slabs. Research facilities are melting various kindsof conventional and exotic metals and alloys, e.g. rareearth alloys, intermetalllc materials, ceramic, uranium,and copper to develop new grades or to purify said

materials.

For these applications mainly drip melting and coldhearth (continuous fiow) melting processes are primarily

used. Button melting serves for cleanliness evaluationespecially of superalloys. Investment skull casting with

an electron beamheat source has been used for the

production of titanium and superalloy turbine parts.

3.1. Drip Melting

Developed as a melting and refining process for the

production of ductile tantalum and niobium ingots, this

technique is nowadaysmainly applied to the refining ofrefractory and reactive metals, e,g, tungsten, tantalum,

niobium, hafnium, vanadium etc.'

To obtain optimum ingot quality in regard to clean-

liness, structure, and surface, the material is remeltedseveral times, starting with raw material, which is nor-mally horizontally fed above the water-cooled copper

ISIJ International. Vol, 32 (1992), No. 5

crucible in the form of bars. Thesebars are mostly com-pacted, presintered, alumino-thermically reduced or pre-consolidated. The continuous cast ingot is of sufficient

purity, however, as a result of the shadoweffect of thehorizontally fed bar, a zone of lower quality is produced,

Fig.

11

12

13

14

IS

1

2

B

L10

s678

9.1

9,2

2. Cross section of a modernhigh power EBgun (type

KSR,manufactured at Leybold).(1) High voltage protection hood, (2) High voltage

isolator with plug and cooling vanes, (3) Cathodeheating system, (4) Gunchamber, (5) Accelerating

anode, water-cooled. (6) Uppermagnetic lens, (7) Gunshutter valve, (8) Ion mirror, (9) Beamguiding system,(9,1) Lower magnetic lens, (9.2) Defiection andscanning system, (10) Vaccumpump, (1 l) Cathodeheating power supply unit, (12) Main high voltage

power supply unit, (13) EBpower control, (14) EBfocussing and distribution power supply, (15) Micro-processor-controlled EBpower and distribution con-trol unit.

making a second remelting necessary.For the second and third melt, the ingot feedstock is

fed vertically (Fig. 4). Theslow rotation of the feedstock(electrode) and the use of two or moreEBguns eliminatethe shadow effect. The molten metal runs down theconical electrode tip, is refined and drops into the centreof the molten pool in the crucible, where it is finally re-fined, homogenized, solidified, and continuously with-

drawn. Thepowerdistribution of the electron beambe-

tween electrode and pool allows control of the pooldepth and bath movement.

Table 2showstypical process data for refractory metalsremelted in drip melting furnaces. Reactive metals, e,g.

zirconium and titanium are predominantly refined in

vacuumarc remelting furnaces to removethe dissolvedhydrogen. However, if the carbon content of zirconiumalso has to be reduced,3) cold hearth melting is moresuitable. Remelting of specialty steels is limited to alloys

with a manganesecontent of less than O.1 "/.. However,the product has an extremely reduced content of un-desired metallic and nonmetallic impurities.4'5)

3.2. Drip Melting Furnaces

Figure 5showsa typical 500kWelectron beamdrip

melting furnace, mainly used for the production oftantalum and niobium ingots. The furnace is equippedwith two EBguns, a horizontal and a vertical feeding

system, a crucible for continuous casting and a with-

drawal system. The vacuumpumpset maintains anoperating pressure below l0~3Pa. View ports allowvisualization of the process via video systems. All

operating parameters such as electron beampower anddeflection, operating pressure, material feed rate andwithdrawal speed are adjusted, controlled, and re-

corded

3.3. Cold Hearth Melting

EBcold hearth melting wasfirst applied about 25 years

ago for the refining of steel.6) Today, cold hearth meltingis mainly used for the recycling and refining of reactive

metal scrap and the refining of superalloys (Fig. 6) andspecialty steels.

Melting in a water-cooled copper hearth has the

advantage over EB-dripmelting, vacuumarc remelting

(VAR) and electroslag remelting (ESR) of separatingmelting, refining and solidification, making individual

control of every single step of the process possible.

2 ~~=13__.l~~!i3: 41 3i: ~!4,._..i 3'4 L~J, 4 5o(~)~o0=ooooo oOoooi

~'--'~~'L~'=~~L_**:i :1

LJ['*~rl 8 ~~)_i, I ---~JI

Jo

Fig. 3.

Computercontrol system for up to 5electron beamguns.(1) EBgun, (2) Manualoverride, static defiection, (3)

Drives for focus and deflection, (4) Emission con-stanter, (5) Manualoverride beampower0-120 o/o, (6)

Intelligent analogue interface board, (7) Keyboard,screen, hard- and floppy-disc drive, (8) Microproces-

sor, (9) Remotecontrol, (lO) Programmablelogic con-troller (PLC).

675 C 1992 ISIJ

ISIJ International, Vol. 32 (1992), No, 5

Contamination-freeenvironment andcruc'ble

Material evaporationand splattering ~LReflected

eectron beam

X*ray emission

Feedstock

,\ ~(\\:~\

Electron beamgun

Flexible power andpower distribution

Scanning electron beam

~)

Flexible melting rate

and refiningdwell time

t~\ •* •';

\*1l~ ~-

~\L_

Drip melt area

Refining in thepool zone

Water-cooied copper crucible

Continuous casting andsoliditying ingot

Fig. 4.

Electron beammelting process (schematic).

Fig. 5. 500kWelectron beamdrip melting furnace.

The hearth design can be adapted to the feeding ofdifferent feedstocks (Fig. 7). Beside bars and compacts,

sponge, scrap and chips can be fed and melted at the

rear end of the hearth. Refining of the material in the

hearth is based on the following processes7,8).

- Vacuumdistillation of highly volatile elements andcompounds,e.g. H, CO.Cl, Nsuboxides.

- Sedimentation of inclusions having a higher density

than the melt (HDIS), e.g. tungsten carbide particles

from titanium scrap. The density of these particles

should be morethan double than that of the melt, andthe size larger than I.5mm to achieve a reliable

separation process. The particles sink down in the

boundary layer betweenliquid and densematerial and

C 1992 ISIJ 676

Frg. 6. Cold hearth (trough) melting of superalloys (sche-

matic).

are trapped in this mushyzone.

- Flotation of inclusions with lower density (minimum40 o/o) in respect to the melt, e,g. aluminum ormagnesiumoxides from steel or nickel-base alloys.

Theselow density inclusions (LDls) with a size larger

than approximately 25 ~mfloat to the surface of the

melt and are retained by means of a mechanical

skimmeror electrothermal barrier. The latter is an EBgenerated small superheated zone covering the entire

width of the heart.

- Adhesion of inclusions with a density comparable to

ISIJ International, Vol. 32 (1 992), No. 5

r urnacety pe

ES2/12/100

ES2/50/400

Material

.Tungsten

1. Melt2. Melt

.Niobium

1. Melt2. Melt

Molybdenum1. Melt2. Melt

Tantalum1. Melt2. Melt

Table 2. Typical process data of somedripmelting furnaces.

Ingot Ingot Melt EBdiameter, weigllt, rate, power,

mJ:l kg kg/h kW

4060

140140

180180

160160

lg 20 9837 22 Ii9

210 25 218206 28 201

415 84 245408 125 290

534 74 276523 80 371

Operatingvacuum,

mbar

5X 10-'

8X 10-6

5x lo-5

8X io-s

5X 10-5

8X 10-6

5X 10-5

8X 10-6

Meltenergy,kWh/kg

4.95.4

8.77.2

2.92.3

3.74.6

Materialyield,

olQ

95.597.5

98.798,l

g8.398.5

93.298.5

CAnalysis, ppm

O N

7044510

804226

20040103286'

lOO115

8

5001901117509012

6504515

30li

5

3309052601011251713

H101l

Brineuhardness.kg/mm2

200

40138 66

1042 140

1052 69

Biilets and Ingots

Liquid metal VIM-Ingot VOD-Ingot

-r

Consolidated scrap

~

E~

Powdersintered bar

Spongecompact li

ATR-Bar

Refining PrOCessin the Trough

Sedimentatron,e. g. Tungsten-earbide particles

from 11-chi psRotation

e.g. Oxides and Nitrides oflower density as the melt

Adhesion on the raft

of oxides, e.g. ofHfOparticles in superalloys

Reaction with slag placedon the melt surface for reduction

of sulfur or increase efficiencyof the adhesion refining

Destillation of volatile elements,e,g. Bi from Superelloys, or

suboxides and COfrom someretactoryand somereactive metals

Soluting of particles or destroyingof themby impinching with the beam

Multi-cast ingots

DSand MCStructure, Continuous cast structure

Globulitic Structure in Slabs

Sponge

\L '

I \chiPs and scrap

Scrap

a

v U,~,~~~*~

Single ingot casting

ul

Multiple ingot casting Slab casting

Fig. 7.

Feedstock for cold hearth melting and re-

fining process using an EBheat source.

677. C 1992 ISIJ

Cro/o 19

ISIJ International. Vol. 32 (1992). No. 5

Content along 150mm~-Ingots

Electrode

Cr

19

18

17

o IngotooLo.

co

avg

Cr Content of Twin Ingots ("/,)

18.43Q~ 75mm 18 66

a)1864 L(2 1847 ~e)

coeo oo

18.318.4Electrode: 19,11

18 51 ~ 0.08 avg.: 18.65 :~: 0.23IngotBottom

IngotMiddle

IngotTopBottom Middle Top

Fig. 8.

Chromiumdistribution in twin ingots.

the melt. Dueto movementof the bath, such particles

fioat to the surface of the melt and are trapped byadhesion in a slag raft of other fioating inclusions.

- Dissolution or dissociation (also LDls) by superheat-ing the bath or abath zone, material is passing through.Relatively high surface temperatures also create fa-

vorable conditions for the evaporation of undesiredtrace elements such as Pb Se Zn Caetc.

' ' ,

- Reaction refining using a reactive gas passing over the

molten material.

Thedegree of purification is dependenton the meltingrate and the hearth geometry. At low melting rates, goodpurification is obtained. However, there is an increase in

the loss of elements having high vapour pressure suchas chromiumand aluminumduring EBmelting.

Reference 1) recommendsnearly square and relatively

deep hearths for vacuumdistillation to allow sufficient

melt stirring. For flotation refining of, for example,superalloys a long and narrow hearth is recommended,whereas for titanium alloy scrap recycling a relatively

short trough can be used. Linked to the hearth only bythe liquid metal flow, the casting and solidification

process can be very fiexibly controlled, thereby ensuring

a homogeneousingot grain structure. The final ingot

maytake various shapes; besides round and rectangu-lar ingots, slabs and hollow ingots9) can be produced.Furthermore, the casting of multiple barsticks with smalldiameters is used in the production of feed material for

VIM- or EB-precision casting furnaces, e.g. whenforgingof the material is critical due to brittleness. For complexgeometrics a sophisticated beam pattern control is

required.

3.4. Cold Hearth Refining for Cleaner MetalsMajor American aircraft engine manufacturers have

issued a material specification, including cold hearthmelting for the production of premiumquality titaniumalloys for aircraft components. It is a proven fact that

non-metallic inclusions have led to failure in aircraft

engines. Therefore, a great deal of effort has been spentto obtain defect-free materiallo) and cold hearth meltinghas proven to be the most favourable process fulfilling

the demandsfor freedom, not only from tungsten carbidetool tips (HDls) but also from titanium nitridesil) andother interstitial high impurities (IHls). These are de-

mands, conventional process routines such as vacuumarc remelting intrinsically cannot fulfil.

Thereduction of nonmetallic inclusions in nickel-basesuperalloys, especially the complete elimination of in-

clusions larger than 10/4m, significantly improves these

mechanical properties.12) EBcold hearth refining is the

C 1992 ISIJ 678

Fig. 9. Four gun2400kWelectron beamdrip andcold hearthmelting furnace.

ideal process to fulfil these requirements in combina-tion with a minimumloss of volatile elements such aschromiumand aluminium, whenthe appropriate hearthlength for the desired melt rate has been chosen. Underthese operating conditions, chromiumlosses are low andnearly constant in the cross section and over the lengthof the ingot (Fig. 8).

Further melt testsl3) of IN 718 showedthat with coldhearth refining the content of LDIS Iarger than 25.5 ,~mcould be reduced from 426 to 19 per pound; alsomulti-strand cast IN 718 barsticks showedno majorsegregation. Typical process parameters and data forthe cold hearth melting of refractory and reactive metalsetc. are given in Table 3.1)

AnEBCHRfurnace for the production of superalloyingots with weights up to 13t is shownin Fig. 9. Four600kWelectron beamguns controlled by the mostmoderncomputerized equipmentare used to realize meltrates of IOOOkg/h and to heat a hearth with a length of1.2 mand a width of 0.35 m. The automated horizontalfeeding of typically VIM-cast electrodes, normally almost

ISIJ International, Vol. 32 (1992), No. 5

Table 3. Refining and production data for the continuous fiow melting of reactive and refractory metals and stainless stcelsin laboratory and pilot production furnaces.

Meta]Fetdl, [ock size,

mm(in rTrouRhsil'*

mm,in.,

Ingot size,

mm(in.I

Ingot weight,hE [[b]

Melt rate.

kg/h (]b/h,

Electron

belmpower,kW

Opcrlth,gpressurc*P. (torr)

Speclncmtiting

energy,kw • h/~E

r Compo$1,Ionof retdstQck Ind ~roduct

-lC, O, N* H, Al, V* Cr,

ppm ppm ppm ppm ~, ~ ~,

Hnfnium. . . . . .

Zirconium. . . .

Zirconium. . . . .

Vanadium

Ti-6AI-4V. . . .

Ti-6Al*4V. . .

Ti-6AI-4V. . . .

Commercially puretitanium.

. . . . . . .

Commercially puretitanium.

. .

Stainless steel. . . .

Alloy 718. . . . .

AISI type 316stainle5s stecl

. . .

60 (2.4, square

IOO (4) square

80 (3.2) square

50 (2) square

Swarf

Soiid scrap

i25 (5) diam

160 (6.3)

Spongc

150 (6) diam

133 (5.2) diam

150 (6) diam

120 * 250(5 x lO)

120 x 300(5 x 12)

120 x 300(5 x i2)

120 x 300(5 * 12)

120 x 300(5 x 12)

120 x 300(5 x 12)

150 x 400(6 x 16)

150 x 250(6 x lO)

150 x 500(6 x 20)

150 x 400{6 x 16)

150 x 400(6 x 16)

150 x 400(6 x 16]

IOO (4) diam

150 (6)

IOO (4)

IOO (4)

l50 (6)

i50 (6)

2x 75 (3)

diam

IOO x 400(4 x 16)

IOO x 400(4 x 16)

2x 75 (3)

diam2x 75 (3)

diam

3x 6S (2.6)

diam

83 O(i83)

9O.5 (200)

40 2(89)

62.6 (138)

62.6 (i38)

2x 32 (70.5)

96.4 (213)

l03.0 (227)

2x 55 (12i)

2x 57 (126)

3x 41.5(9 1.5)

40 (88)

42 (92.5)

80 (176)

20 (44)

40 (88)

70 (154)

91 (200]

86.3 (190)

41 .2 (9])

136 (300,

136 (300)

i80

l85

l40

l30

122

l40

147

148

226

144

156

136 (300) 156

4 x lO-:(3 x IO-d)

3.5 x l0-2(2.6 x l0-4)

3.5 x l0-2(2.6 x l0-4)

[ 5x lO-:(1.1 x l0-4)

2x l0-2(1.5 x lO-')

7x lO-:(5.3 x l0-4)

6x l0-2(4.S x lO~d)

6x l0-2(4,S x '0~4)

8x lO-2(6 x l0-4)

6x l0-2(4.5 x l0-4)

6x l0~2(4.S x t0-4)

6x l0-2(4.5 x l0~4)

4.5

4.4

l .75

6.5

3.0

2.0

[.61

l,71

5,5

[.06

l,15

i.15

900600950 95540 30

40OO 8001520 210l045 210277 50

400 2eOO IIO200 2700 IIO

1520 1520 751320 76

701 97 155536 33 68

417 14 S2363 17 34

30

3lO

3lO

38421~

IS

8

6,04.46.04.86.03.6

0.72

9999

4.0

424.04. 14.04.3

18.2518. Il19, Il18.73

ttt

Skull

Met

1

Single Low Densily Inclusions

electrode

--2--

Conglomeraled (Rafl )

l~

;J''~'L

'"f~

' .'1~

1 preheating 2 tip

I~

shaplng 3

~ime(min )driP melting

VIM-castFig.

738lO.

VIM-ESR-meI t ed VIM-EBCF-c I eanedButton melting process and button samples of superalloys.

679 C 1992 ISIJ

ISIJ International, Vol. 32 (1992). No. 5

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Fig. Il. Outlook on methods for production of reactive metals.

free of non-metallic inclusions and trace elements,14)allows continuous production. The height of themechanical barrier is adjustable during the process.Withdrawal crucibles for round ingots of 0.8 mdiameteror slabs of e.g. 1.35mx 0.25mcan be installed to castingots up to a length of 3.5 m.

Smaller EBsystemswith melting powerof 20(>300kWare equipped with a cold hearth of approx. 150mmwidthand 400mmlength. The water-cooled mechanical slagbarrier separates the surface of the hearth into two areas.Oneof two installed EBguns melts the feedstock andheats the rear part of the trough. Thesecond gun heatsthe hearth in front of the barrier, the overflow lip andthe pool in the withdrawal crucible for ingots of up to250mmdiameter.

3.5. Button Melting

Button melting processes are used to analyze thequality of steel or superalloy cast parts especially in

regard to the content of low density inclusions (LDls).4)

A sample of the material is drip melted in a processfollowing predefined steps with controlled EB powerdistribution so as not to destroy the nonmetallic in-

clusions (Fig. 10). During the directional solidification

process the nonmetallic inclusions are concentrated in

the centre of the button for further metallographic in-

vestigations. However, the raft gives the first infor-

mation about the quantity of impurities in the sample.

4. Future Directions

Industrial demandsfor highly clean materials and areliable production system are still increasing: oneexam-ple is the aircraft industry request for alloy cleanliness

improvementand crack growth resistant materialsl5) tobe applied in engine disks. Production economics mustalso be improved: by using lower grade feeding materialwith reduced pretreatment input, the casting of near-endshape products like thin slabs or hollow ingots, the

recycling of condensates occurring during the meltprocess and the increased use of computers to controlthe process basedon data-feedback by continuous in situanalysis of the molten material.

Theseincreasing demandsfor material producedunderextremely clean and reproducible conditions, and thedevelopment and application of new materials like

ceramic-free powdersof reactive metals andalloys havingintermetallic phases (Ti-Al, Ni-Ti, Ti-Si) will continueto drive progress in the electron'beam melting technology.An outlook on these applications is shownin Fig. 11,

whereby electron beammelting will replace or supple-

ment existing methods.

1)

2)

3)

4)

5)

6)

7)

8)

9)

lO)

REFERENCESW.Dietrich andH. Stephan: Electron BeamMelting andCasting,Metals Handbook,Vol, 15, Casting. ASMInt., Ohio, (1 988), 419.

H. Ranke, V. Bauer, W. Dietrich, J. Heimerl and H. Stephan:Melting and Evaporation with the Newly Developed Leybold-Heraeus600kWEBGunat Different Pressure Levels, Proc. Conf.Electron BeamMelting and Refining, Reno, ed. by R. Bakish,(1985), 286.

H. Stephan: Production of Ingots and Cast Parts from ReactiveMetals by Electron BeamMelting and Casting, Proc. 3rd EBProcess. Seminar, Stratford, (1974), 150.

C. E. Shamblen, S. L. Culp and R. W. Lober: SuperalloyCleanliness Evaluation Using the EBButton Melt Test, Proc.Conf. Electron BeamMelting and Refining, Reno, (1983), 61.

F. Hauner. H. Stephan and H. Stumpp: Metall., 2 (1986), No.40, 2.

C. d'A. Hunt and H. R. Smith: J. Met., 18 (1966), 570.

H. Stephan: Metal/., (1975), 704.

C. d'A. Hunt. J. C. Loweand T. H. Harrington: Electron Beam,Cold Hearth Refining for the Production of Nickel and CobaltBase Superalloys. Proc. Conf. Electron BeamMelting andRefining, Reno, ed, by R. Bakish, (1983), 295.

H. R. Harker: The Present Status of Electron BeamMeltingTechnology, Proc. Conf. Electron BeamMelting and Refining,

Reno, ed, by R. Bakish, (1986), 3.

H. Pannen, G. Sick and D. M. Wainhouse: High PowerPlasmaMelting of Titanium, Proc. Sixth World Conference on Titanium,(1988), 597.

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ISIJ International, Vol. 32 (1 992), No. 5

ll) R. G. Reddy: Kinetics of TiN Dissolution in Ti Alloys, Proc.Conf. Electron BeamMelting and Refining, Reno, ed, by R.Bakish, (1990), I19.

12) J. K. Tien and E. A. Schwarzkopf: Assessing the Needsfor EBRefining of Superalloys, Proc. Conf. Electron BeamMelting andRefining, Reno, ed. by R. Bakish, (1983), 6.

13) F. Shimizu, T. Denda, N. Mori and K. Numa:Proc. Conf.Electron BeamMelting and Refining, Reno, ed, by R. Bakish,(1989), 134.

14) M. Krehl and I. C. Lowe: Electron BeamCold Hearth Refiningfor Superalloy Revert for Usein FoundryProduction. Proc. Conf.Electron BeamMelting a~rd Refining. Reno, ed. by R. Bakish,(1986), 286.

15) C. E. Shamblen: Ongoing Challenges for Titanium AlloyCleanliness Improvementin Aircraft EngineDisk Materials. Proc.Conf. Electron BeamMelting and Refining. Reno, ed. by R.Bakish, (1990), 49.

681 C 1992 ISIJ