Heat resistant super alloys - Application guide

132 Pages·2010·25.37 MB·English

APPLICATION GUIDE
Heat Resistant Super Alloys

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C-2920:034 US/01 © AB Sandvik Coromant 2010.08
Printed on recyclable paper. Printed in Sweden, AB Sandvikens Tryckeri.
High pressure coolant machining
for better productivity and results
More information
Useful information and application techniques can be found in our
catalogs, handbooks and application guides, such as PluraGuide.
CoroGuide web is an internet-based catalog including a cutting data
module (also available on CD) where you can find cutting data rec-
ommendations for your specific application.
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www.sandvik.coromant.com
www.aero-knowledge.com Acknowledgement
Some sections of this article present the findings of technical investigations
carried out by the AMRC* which are sponsored by Sandvik Coromant.
* The Advanced Manufacturing Research Centre (AMRC) is a partnership which builds on the shared scientific
excellence, expertise and technological innovation of industrial partners and world-class research within the
University of Sheffield’s Faculty of Engineering.
Contents
Introduction 2 4. Milling 60
Production planning process 61
1. Heat resistant super alloys – HRSA 3
Typical components 61
Alloy groups 4
Machining strategy 62
Machinability/raw material
condition 5 Cutter concept 64
Common component types 7 Milling process with indexable inserts 65
Coolant requirement 8 Face milling with carbide inserts 68
End milling/90 degree approach 77
2. Turning of nickel-based materials 9
Ceramic milling 82
Machining stages 9
Solid carbide – CoroMill Plura in
Typical wear mechanisms 11 HRSA machining 88
Insert shape selection 13 Exchangeable-head CoroMill 316
Cutting tool materials 21 in HRSA machining 97
Ceramic insert grades 22 Component/feature based solutions 98
Carbide insert grades 26 Recommended start cutting data 102
SCL – predictive machining 28
5. Hole making 104
Geometries and chip breaking 31
Hole types and hole making methods 104
Recommended starting choices 34
Tools for hole making 106
Tailor Made 36
Circular ramping from solid 107
Engineered solutions 37
Circular interpolation of existing holes 108
Component/feature solutions 42
Back chamfering/deburring 109
3. Turning of cobalt-based materials 51 Thread milling 110
Process considerations 52 Recommended start cutting data 112
Typical wear recommendations 53 Component/feature solutions 114
Insert shape selection 54
6. Technical data 118
Optimized tools for internal machining 55
Recommended starting choices 57 7. Material cross-reference list 120
Carbide insert grades 58
Engineered solution 58
Component/feature solutions 59
Introduction
This application guide concentrates on opti- Productivity along with quality and reli-
mizing machining of heat resistant super ability are our focus. When we talk about
alloys (HRSA). productivity you will see that we measure
For one of the most challenging material this in terms of inch3/min. It is important
groups to machine, optimized tools are nat- to understand the relationship between the
urally a prerequisite, but equally important combination of speed, feed and depth of
is how to apply them. cut and not just cutting speed alone which
is often the most damaging parameter
We will guide you through the most com-
when considering tool life.
mon materials and machining applications.
We aim to give you application and process
recommendations that will help you use our
products in the most productive manner
with maximum process reliability and com-
ponent quality.
Our goal is to support customers with
complete tooling solutions that meet cost
reduction and quality improvment initiatives.
2
Heat resistant super alloys – HRSA
Heat resistant super alloys (HRSA) are a family of alloys utilized in
various industry segments:
Aerospace engine – combustion and turbine sections.
Stationary gas turbines – combustion and turbine sections.
Oil and gas – marine applications.
Medical – joint implants.
The properties which make them attractive are:
• Retension of strength and hardness at high temperatures.
• Corrosion resistance.
Aerospace engine Stationary gas tur- Oil and gas Medical
bines
3
Alloy groups
HRSA materials fall into three groups: However, they have the poorest hot strength
nickel-based, iron-based and cobalt-based properties of the three groups.
alloys. The physical properties and machin- Common types:
ing behavior of each varies considerably,
• Inconel 909
due both to the chemical nature of the alloy
and the precise metallurgical processing it • A286
receives during manufacture. Whether the • Greek Ascoloy
metal is annealed or aged is particularly
influential on the subsequent machining Cobalt-based display superior hot corrosion
properties. resistance at high temperatures compared
to nickel-based alloys. They are more expen-
Nickel-based are the most widely used, and sive and also more difficult to machine due
currently constitute over 50% of the weight to their great wearability.
of advanced aircraft engines. The trend is
The use in turbines is restricted to combus-
that this will increase in new engines in the
tion parts in the hottest engine areas.
future.
Their main use is seen in surgical implants,
Common types include:
which utilize their inherent corrosion resist-
• Inconel 718, Waspaloy, Udimet 720 ance.
– precipitation hardened
Common types:
• Inconel 625 – solution strengthened (not
• CoCr
hardenable)
• Haynes 25
Iron-based have been developed from • Stellite 31
austenitic stainless steels. Some have very
low thermal expansion coefficients (such
as Incoloy 909) which make them espe-
cially suited for shafts, rings, and casings.
The most common HRSA alloys (see page 120 for the complete list)
Alloy Code Material Hardness HB
group Ann. Aged
Nickel MC S2.0.Z.AN CMC 20.2 Inconell 718 425
Inconell 706 285
Inconell 625 200
Hastelloy S
Hastelloy X 160
Nimonic PK33 350
Udimet 720
Waspaloy
Iron MC P5.0.Z.AN CMC 05.3 Greek Ascoloy 300
MC M1.0.Z.PH CMC 05.4 A286 300
MC S2.0.Z.AN CMC 20.21 Incoloy 909
Cobalt MC S3.0.Z.AG CMC 20.3 Haynes 25
Stellite 21 280 340
Stellite 31
4
With such a wide spread of materials under the generic heading of HRSA the machining
behavior can vary greatly even within the same alloy group. In fact the same material can
have numerous machining recommendations.
Heat generated during cutting
(tendency for plastic deformation)
Hardness = Stainless
HB steel
Nimonic 1023 = Heat treated
(aged)
Inconel 718
400 Nimonic 80A = Solution
Nimonic PK 33 treated
Waspaloy (annealed)
Incoloy 901
Nimonic 90
Nimonic 105
300 17-4 PH Tendency
for notch wear
Nimonic 263
Crucible
Jethete A286
M152
200 Incoloy 901 Precipitation hard enable
alloys in annealed conditions
Nimonic 75
Austenitics Incoloy 800 Inconel 625
Sanicro 30
100
Stainless Fe based alloys Ni based alloys
steels
Weight %
10 20 30 40 50 60 70 80 90 Nickel & cobolt
Machinability/raw material condition
Heat treatment
Annealing – heating to controlled temperature then cooling at <30HRC
controlled rate.
Solution treatment – heating followed by rapid cooling <30HRC
Aging – slow cooling after solution treatment up to 48HRC
The state of heat treatment affects the Insert grades with greater toughness and
hardness of the component and hence the reduced hot hardness – resistance to high
wear mechanisms. The formation of the temperatures – are required due to reduced
chip is a good indicator of the hardness; cutting temperatures and increased chip
with hard materials it is easier to break the hammering. Here, damage to areas outside
chip. the actual cutting edge is caused by the
Hardened materials have increased cutting chip breaking against the insert.
temperatures and show a tendency towards
notching of the cutting edge at the depth
of cut. The combination of a low entering
angle and a hard substrate with a coating
offering a heat barrier is required.
5
Comparison of wear depending upon
material hardness and insert grade
CNMX 43A1-SM – v 164 ft/min, f .0098 inch/rev, a .059 inch
c n p
Hard material Soft material
GC1105 S05F GC1005 S05F
6 min 12 min 7 min 3.5 min
Chip hammering
Raw material production method
Depending upon the size, shape and The production method varies the machina-
strength requirements of the component, bility of the material and will change the
various production methods for the blank wear characteristics.
material will be adopted.
Material Components Advantage/suitability Machinability
Forging large high strength medium
Casting complex shape low strength poor
Bar stock <8 inch diameter availability/strength good
Each of these raw material types directly to be most sensitive to notch wear and
affects the alloy’s micro structure, and so abrasive wear. They can be easily identified
also affects the subsequent machining due to their visibly mottled surface (the
behavior: ‘orange peel’ effect).
Forged materials have a finer grain size Bar stock material is the easiest form of
than in castings, which improves the raw material to deal with. Notching is not
strength and grain flow of the component. so much of a problem, which allows harder
When machining forgings, reducing the and more wear resistant insert grades to
speed and increasing the feed generally be used than for forgings.
gives the maximum possible metal removal
rate with good tool life.
In castings the opposite applies, and apply-
ing low feeds (.004 inch chip thickness)
and higher speeds can be beneficial.
Castings have poor machinability and tend
6
Common component types
Typical HRSA components, and an indication of the different machining methods involved
for each include:
Aerospace and gas turbine – nickel based
Component Turning Milling Drilling Others
Discs 60% 10% 5% 25%
Casings 45% 40% 15%
Rings 95% 5%
Blades 10% 50% 40%
Blisks
Impellers
Shafts 70% 5% 25%
Medical – CoCr
Component Turning Milling Drilling Others
Cup 90% 10%
Head 90% 10%
7
Coolant requirements
Coolant should be applied in all operations
excluding milling with ceramics. The volume
should be high and well directed.
High pressure coolant HPC (up to 1160 psi)
shows positive results in terms of tool life
and consistency.
Dedicated HPC-tools with fixed nozzles give
HPC improves the chip control
parallel laminar jets of coolant with high
CNGG 120408-SGF
velocity accurately directed at the right zone
vc 213 ft/min, ap .040 inch, fn .008 inch/rev
between insert and chip. Inconel 718
For milling and drilling, all tools with internal
coolant supply can benefit from HPC even if
tools prepared for nozzles give higher pos-
sibility to use smaller nozzle diameters for
high pressure. CoroTurn HP tool, 1160 psi Conventional tool
• Turning, use at least 5 gal/min and a Compared chips made with a CoroTurn HP tool versus a
basic pressure of 1015 psi. conventional tool and standard coolant pressure.
• Milling and drilling, use at least
12 gal/min to accomodate the extra noz-
zles on the milling cutter and the largest
drill diameters.
Flow required for specified nozzle diameter and 1160 psi high pressure pump
The pressure (p) hitting the cutting
zone is dependent on the number Flow, ν Nozzle diameter, d
of nozzles, the nozzle diameter gal/min
(d) and the flow (ν) given from the ∅ .020 inch
pump. 26 ∅ .040 inch
24 ∅ .060 inch
∅ .080 inch
A higher flow rate is needed for 21 ∅ .100 inch
tools with many outlets or large 19 ∅ .120 inch
∅ .140 inch
hole diameter for the coolant. 16
13
11
8
5
3
0
1 5 10 15 20 25 30
Number of nozzles
8