Refractory Metals for the

Foundry Industry

Application of Refractory Metals for Corrosion Problems

High Corrosion Resistance

A good corrosion resistance against molten metals is the prerequisite for a permanent application of die materials in the Foundry

Industry. It has already been known for a long time that refractory metals and their alloys show an excellent corrosion resistance

in comparison to hot working steel. New scientific investigations of the mass loss of refractory metals in molten aluminium

confirm these facts (see graphic on the next page). Hence, the application of PLANSEE-Materials in critical areas of the die

guarantees outstanding results:

- Tungsten- and Molybdenum alloys are particularly suitable for the casting of aluminium and brass. Cores and die inserts due

to their excellent corrosion resistance show a fundamentally higher tool life than any other conventional die material i.e. hot

working steel.

- An optimal surface quality of the casting can be achieved even after long tool life. Consequently the expenditure for cleaning

and maintenance is considerably reduced. At the same time the low thermal expansion coefficient helps maintain tighter

tolerances of the cast parts.

- Cores and inserts from refractory metals reduce typical sticking effects of aluminium on the die surface, and therefore,

reduce the amount of maintenance even further.

2

Cross section of a D2M (Surface carborised) after 12,5 days in AlSi9Cu9 Melt Mass

loss <5%

Cross section of a TZM rod with TiB2 after 12,5 days in AlSi9Cu9 Melt Mass loss 1%

Cross section of a TZM rod after 12,5 days in AlSi9Cu9 Melt Mass loss 5%

- Due to the insolubility of Molybdenum and Tungsten in molten Aluminium compared to hot working Steel, inserts and cores

do not suffer from any erosion, which typically occurs when the parts are subjected to molten aluminium injected at high

velocities.

Filter Inserts Spreader for Al-Wheel Casting made of PLANSEE material

Graph 1: Mass loss of different materials in AlSi9Cu9 melt.

3

REM picture of a steel surface (1.2343) full with cracks due to thermal fatigue (heat

checking) after 45.000 cycles

- Dies, cores and inserts made of Tungsten and Molybde-

num alloys are very resistant to heat checking cracks as

the thermal expansion coefficient is 1/3 of Steel. As a result

the tool life is much longer.

- The application of PLANSEE materials eliminates the pro-

blem of heat checking cracks. The finished castings have

an optimal surface quality, which reduces the scrap rate as

well as maintenance requirements.

- The graph below (Graph 2) shows that the hardness of hot

working steel reduces dramatically after a certain number

of temperature cycles due to thermal fatigue. Although re-

fractory metals have a lower surface hardness initially, it

can be seen from the graph that the hardness stays the

same or even increases slightly.

Hence, the combination of high thermal conductivity and

low thermal expansion prevents the formation of heat che-

cking cracks.

Application for Heat Checking Problems

No Heat Checking Cracks

The die life, among other influences, is shortend by heat checking cracks (see picture below). This particularly applies to high pres-

sure die casting. The occurrence of heat checking cracks increases with an increasing temperature difference between the surface

layer and the underlying material layers as well as high thermal expansion and low hot strength of conventional die materials.

Tungsten and Molybdenum alloys have an excellent resistance to heat checking due to their low thermal expansion and good hot

strength at elevated temperatures. Additionally the high thermal conductivity guarantees a better temperature distribution and a

lower temperature difference between the surface and the core material layers (see Graph 2).

Graph 2: Maximum surface temperature versus energy input Graph 3: Surface hardness in Vickers versus temperature cycles

4

Improved Cooling Effect

In addition to their excellent corrosion and thermal fatigue

resistance, refractory metals have other physical and mecha-

nical properties that provide the die castor with completely

new opportunities for the die casting process. In case of fast

heat transfer requirements, Molybdenum and Tungsten al-

loys present excellent possibilities.

• In order to avoid shrinkage porosity in hot spots of the cas-

ting, a sufficient cooling effect must be ensured. The ther-

mal conductivity of Tungsten and Molybdenum alloys is 3

- 5 times higher than that of conventional die materials. This

offers a distinct higher cooling potential (see pictures on the

right).

• The application of these materials can be used to influence

the quality of the castings i.e. improve the mechanical pro-

perties by reducing the DAS (Dendrite Arm Spacing).

• In some cases complicated, maintenance intensive cooling

systems can be eliminated since the heat can be dissipated

sufficiently with refractory metals.

• The high thermal conductivity can also be used to reduce

the cycle time of some casting processes.

Cou

rtesy

of T

CG

UN

ITE

CH

AG

Die insert for Al-HPDC process made of PLANSEE material

Die insert for Al-Wheel Casting made of PLANSEE material Core pin for Al-HPDC process made of PLANSEE material

Application for Shrinkage Porosity Problems

D185 combustion chamber die inserts

Surface temperature of the die

with hot working steel core pins upon opening

Surface temperature of the die

with one TZM core pin upon opening

5

Mechanical and Physical Properties of PLANSEE-Materi-als in Comparsion with H13 (1.2343) Hot Working Steel

Properties

Mo TZM D2M D176 D185 1.2343

Corrosion ++ ++ + + + --

Oxidation from 400 °C from 400 °C from 600 °C from 600 °C from 600 °C no problem

Thermal conductivity (500 °C) [W/m K] 127 127 65 75 90 28

Thermal shock resistance ++ ++ ++ ++ ++ --

Notch impact strength + 0 - - - ++

Rm (RT) [MPa] 650 780 990 880 800 1200 - 1600

Rm (500 °C) [MPa] 440 500 670 570 600 850 - 1100

Rp0.2

(RT) [MPa] 600 730 700 620 600 1000 - 1400

Rp0.2

(500 °C) [MPa] 400 490 460 390 420 650 - 900

A5 (RT) [MPa] 40 19 18 20 10 10 - 15

A5 (500 °C) [MPa] 30 15 16 17 7

Young's Modulus [GPa] 320 320 360 360 385 215

αth (20 - 500 °C) [·10-6 K-1] 5.5 5.5 5.3 5.5 5.0 12.9

Hardness [HRC] 23 25 34 31 34 > 45

Machining / Repair welding 0/-- 0/-- +/0 +/0 +/0 ++/++

Comparison of different die materials: ++ = excellent; + = good; 0 = sufficient; - = bad; -- = unsuitable

Comparison of tensile strength versus temperature Comparison of notch impact strength versus temperature

Comparison of thermal conductivity versus temperature Comparison of thermal expansion coefficient versus temperature

6

Products made from DENSIMET® are manufactured by the powder metal route. In the production of DENSIMET®, powdered

metal mixes are pressed and liquidphase sintered to produce a 100% dense and solid material. The sintered product can be

supplied as a semifinished product, a net-shape product or a finished product. According customer’s demand, PLANSEE can

also produce DENSIMET® components to meet special requirements by shaping and heat treatment techniques.

DENSIMET® WR has been developed as special weld filler material for the joining and repairing of DENSIMET® Alloys.

Powder Raw Materials

Molybdenum

Nickel

Iron

Tungsten

Pressing Sintering and heat treating Semi-finished products

Netshape products

Finished products

The Manufacture of DENSIMET® Tungsten-Alloys

Material Abbrevation Chemical Composition [%] Density

W Rest

DENSIMET® 170 D170 90.0 Ni, Fe 17.0

DENSIMET® 176 D176 92.5 Ni, Fe 17.6

DENSIMET® 180 D180 95.0 Ni, Fe 18.0

DENSIMET® 185 D185 97.0 Ni, Fe 18.5

DENSIMET® D2M D2M 90.0 Ni, Mo, Fe 17.3

DENSIMET® WR WR 70.0 Ni, Fe 12.5

Schematic diagram of the manufacturing process of DENSIMET® products

7

The Manufacture of Molybdenum and its Alloys

PLANSEE manufactures the refractory metal molybdenum by powder metallurgy. Molybdenum trioxide and ammonium molyb-

dates are the starting materials for the production of molybdenum powder. In order to achieve the best powder quality these

molybdenum raw materials are reduced in hydrogen. After processing and homogenization the molybdenum powder is pressed

into rods or plates of different geometry and dimensions, depending onthe intended end-use i.e. wire, rod or sheet. Pressing is

carried out by means of linear and isostatic presses. In the latter case, a bag is filled with the powder and subjected to hydrostatic

pressure from all sides. The pressed compacts are sintered in hydrogen at temperatures of 2000 - 2200 °C (2273 - 2473 K). The

sintering imparts the strength and density to the compacts necessary for further processing.

The sintered blocks are extruded, forged, rolled or swaged at temperatures of 1200 - 1500 °C (1473 - 1773 K). The density incre-

ases with the degree of reduction. Forgings, round bars and sheets are mad in this manner.

Material Chemical CompositionMelting Point

[°C]

Density

[g/cm3]

Mo min. 99.97 % 2617 10.2

TZM0.5 % Ti, 0.08 % Zr

0.01 -0.04 % C, Rest Mo2617 10.2

MHC 1.2 % Hf, 0.1 % C, Rest Mo 2617 10.2

Annealing

MoO3

Mo

Alloy additions

Reduction

Forming

Isostatic

Uni-axial (Matrices)

Raw material Alloying Mixing

Thermo-mechanical treatment Sintering Pressing

8

Complex machined parts for alloy wheel casting made from PLANSEE-Materials

TZM hot runner nozzles

Coating

In some applications the lower hardness value of PLANSEE refratory alloys might result in surface damages. As classical hard-

ening by heat treatment is not suitable for Molybdenum and Tungsten materials, coating methods have to be employed to pro-

tect the surface of parts machined thereof. We recommend the use of simple and well known PVD-coatings like CrC or TiAlC.

PLANSEE has also developed its own wear resistant surface coating to increase the surface hardness level up to 1000HV while

corrosion resistance is not influenced at all. In air or any oxidizing atmosphere at temperatures up to 400°C the oxidation of Mo-

lybdenum is rather negligible, whereas at temperatures above 600°C severe oxidation or to be more precise sublimation takes

place. For DENSIMET® Tungsten alloys slight oxidation starts at 600°C. From the experience in casting industry there are no

problems arising with oxidation, as the temperature level is around 400°C - 500°C when demoulding the casting from the die. The

usually applied refractory coating offers an additional protection to oxidation. When filling the die the surrounding atmosphere is

displaced by the inflowing melt, and oxidation is supressed.

Machining

Machining

The machining of tungsten composite materials (e. g. DEN-

SIMET®) is slightly more difficult than the machining of steel.

By following the guidelines for machining in the next section,

you will obtain the surface qualities you require.

Molybdenum is more difficult to machine. It has certain pro-

perties, that have to be taken into account. A knowledge of

these properties and adherence to the recommendations

provided on the next page is necessary for successful ma-

chining and working of molybdenum.

In general you should take care of rigid supports and sharp

tools. Please use hard metal tooling with positive cutting ge-

ometry as used for the machining of aluminium (Please ask

for our CERATIZIT hard metal tooling delivery program).

Spark Erosion

Complex shapes and perforations in tungsten or molybde-

num alloys can be made by spark erosion. The part to be ma-

chined is the anode, the machining electrode is the cathode.

We recommend the tungsten-copper material SPARKAL® as

an electrode material (please refer to our brochure “SPAR-

KAL® Erosion Electrodes”).

TZM-parts for plastic injection moulding

9

Recommended Conditions for Machining of Mo, TZM and Mo/W-Alloys

Milling - with Hardmetal Inserts of Following Geometry

Rake angle γ ≥ + 10°

Front clearance 0 to 10°

Hardmetal grade H 216 T / H 210 T

Cutting speed [m/min] vc = 100 - 150

Feed/tooth [mm] f = 0.03 - 0.10

Coolant Emulsion

HSS-Tools

Cutting speed vc = 20 - 25 m/min

Rake angle γ ≥ + 10°

Coolant Emulsion

Turning

Tools CERATIZIT Maxilock-S Code-27 and -25, HM grade H 216 T / H 210 T

Cutting speed [m/min] vc = 100 - 140

Feed [mm/U] f = 0.05 - 0.35 (acc. to corner radius)

Cutting depth [mm] ap = 0.3 - 6.0 (acc. type of insert)

Coolant Emulsion

Drilling - Drill Diameter up to 18 mm

Drill HSS (if possible with internal coolant channal)

Cutting speed [m/min] vc = 10 - 15

Feed [mm/U] f = 0.05 - 0.10

Coolant Emulsion

Tapping

Tips in HM grade H 10 T / H 20 T

Cutting speed [m/min] vc = 300 full cooling with emulsion

Delivery ap = 0.002 mm/pass

10

Machining of Densimet®

Turning

ToolsCERATIZIT Maxilock S

CERATIZIT Maxilock N

Indexable inserts H 216 T / H 210 T, TSM20

Code -25 / -27 / -42

positive cutting geometry

sharp cutting edges

Cutting speed [m/min] vc = 60 - 140

Feed [mm] f = 0.05 - 0.30

Cutting depth [mm] ap = ≤ 6

Coolant Emulsion

Milling

Use CERATIZIT milling tool systems Maximil and Helimax with positive cutting edges of the following geometry:

Rake angle

Front clearance

Hardmetal grade

0° to + 10°

0° to + 5°

H 216 T / H 210 T

End mills micrograin K10 uncoated DIN 2535 HB

Cutting speed [m/min] vc = 70 - 150

Feed / tooth [mm] fz = 0.03 - 0.15

Coolant dry

Tapping

Tools VA nitrided taps with straight flutes and a tensile strength of 1400 N/mm2

Coolant Cutting oil

Drilling

Hardmetal grade H 216 T / H 210 T (CERATIZIT)

Drilling diameter < 18 mm

Drill HSS or hardmetal twist drill

Cutting speed [m/min]HM: 30

HSS: ≥ 8 - 15

Drilling diameter ≥ 18 mm

Drill Short hole drill

Cutting speed [m/min] HM: 70 - 160

Indexable inserts WCGT Grade U 17 T

Cutting speed [m/min] vc = 70 - 100

Feed [mm] f = 0.03 - 0.10

Coolant Emulsion

11

Material Properties for Finite Element Simulation (Typical Values)

Molybdenum-Alloys

Densimet®/W-Alloys

Hot Working Steel

Mo

T

[°C]

ρ

[g/cm3]

cp

[kJ/kg K]

λ [W/m K]

α [ • 10-6 1/K]

E

[GPa]

Mo-Panel Ø 25 mm Annealed

Tensile Test

Rm [MPa] R

p0.2 [MPa] A

5 [%]

20 10.20 0.256 148 5.32 339 678 614 41

200 10.19 2.266 137 5.38 328 588 530 38

500 10.18 0.281 127 5.53 309 440 398 32

800 10.15 0.296 121 5.73 289 285 281 21

1000 10.14 0.306 119 5.88 274 217 215 22

1500 10.10 0.330 114 6.30 231 60 40 55

TZMT

[°C]

ρ

[g/cm3]

cp

[kJ/kg K]

λ [W/m K]

α [ • 10-6 1/K]

E

[GPa]

TZM-Panel Ø 25 mm Annealed

Tensile Test

Rm [MPa] R

p0.2 [MPa] A

5 [%]

20 10.20 0.256 148 5.32 339 789 738 19

200 10.19 2.266 137 5.38 328 702 554 16

500 10.18 0.281 127 5.53 309 502 493 15

800 10.15 0.296 121 5.73 289 445 440 15

1000 10.14 0.306 119 5.88 274 386 374 19

1500 10.10 0.330 114 6.30 231 150 140 40

D2MT

[°C]

ρ

[g/cm3]

cp

[kJ/kg K]

λ [W/m K]

α [ • 10-6 1/K]

E

[GPa]

Rm

[MPa]

Rp0.2

[MPa]

A5

[%]

20 17.3 0.149 65 5.3 360 990 670 18

200 17.2 0.156 66 5.5 350 890 600 17

500 17.1 0.160 68 5.6 333 700 460 16

800 17.0 0.163 69 5.7 320 490 330 14

D176T

[°C]

ρ

[g/cm3]

cp

[kJ/kg K]

λ [W/m K]

α [ • 10-6 1/K]

E

[GPa]

Rm

[MPa]

Rp0.2

[MPa]

A5

[%]

20 17.6 0.162 75 5.5 360 880 620 20.0

200 17.5 0.166 76 5.7 350 760 540 18.5

500 17.4 0.173 78 5.8 333 570 390 17.0

800 17.3 0.175 79 5.9 320 400 270 16.0

D185T

[°C]

ρ

[g/cm3]

cp

[kJ/kg K]

λ [W/m K]

α [ • 10-6 1/K]

E

[GPa]

Rm

[MPa]

Rp0.2

[MPa]

A5

[%]

20 18.5 0.145 90 5.0 385 800 600 10

200 18.4 0.149 91 5.1 365 720 520 9

500 18.3 0.154 92 5.2 350 600 420 7

800 18.2 0.158 93 5.3 340 480 320 5

1.2343

T

[°C]

ρ

[g/cm3]

cp

[kJ/kg K]

λ [W/m K]

E

[GPa]

α [ • 10-6 1/K]

Rp0.2

[MPa]

Rm

[MPa]

20 7740 0.461 25.0 217.6 8.7 1300 1500

100 7720 0.496 26.0 212.9 8.7 1250 1450

300 7670 0.568 27.4 198.2 17.4 1100 1300

500 7600 0.677 26.8 178.9 13.2 750 950

700 7540 1.400 26.2 158.2 8.9 400 550

900 7530 0.620 26.8 143.2 22.2 200 300

1100 7420 0.630 28.9 128.3 27.1 73 100

1300 7300 0.665 31.8 113.3 31.5 19 30

700093709.11 (1500) RWF

Close to the customer - our global network

PLANSEE manufactures and markets its products worldwide. Production sites in Europe, USA and Japan and a global network

of sales subsidiaries and sales partners, enable outstanding customer service and product quality delivered by local teams.

Stronger than any alliance and more diversified than single producers, PLANSEE is the most reliable source for high performance

components made of refractory metals.

For more information and local contacts please visit our website:

www.plansee.com