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