Die Steel Handbook

Transcription

Die Steel Handbook

HOT WORK DIE & MOULD STEELS
2 kg to 36 tonnes
SOMERS FORGE LIMITED
Quality is remembered long after price is forgotten!
CONTENTS
Page
3
Page
4‐5
Page
7
Page
8‐9
Somers Solidised™ Die and Mould Steels
Supply Conditions and Related Specifications
Wear Resistance and Relative Toughnesss
Die Steel Selection Chart
Page 10‐11
Machinability
Page
14
No. 5 Electem
Page
15
Somdie and
Somtherm
Page
16
Thermodie
Page
17
Hydie
Page
18
Bestem
Page
19
VWMC
Page 20‐21
VMC and
Hytuf
Page
22
Somplas 30
Page
23
Supamold
Page 24‐25
Fracture and Notch Toughness
Page
26
Thermal Fatigue Resistance
Page
27
Hot Tensile Properties
Page 28‐29
Hardness Conversion Table
Page
Stress, Metric and Temperature Conversion Tables
Page 2
31
SOMERS SOLIDISED™ DIE & MOULD STEELS
In service, die blocks have severe working
stresses imposed upon them and often oper‐
ate under a triaxial stress condition. Somers
Forge has developed a specialised forging
technique whereby the the mechanical prop‐
erties of the heat treated die block can better
withstand the normal shock loading charac‐
teristics of the metal forming process.
Solidised grain flow is highly beneficial to die
life. To achieve best results, the mechanical
properties of the heat treated die block must
be balanced between those present in the
longitudinal plane and those existing in the
transverse axis.
For example, if a die block is direct forged by
simply “drawing out”, whilst the longitudinal
properties are satisfactory, the transverse
ductility and notch strength are greatly im‐
paired. Upset forging minimises the loss of
transverse toughness. Lengths of die steels
can be supplied from our specially processed
bars held in our Steelstock Divisions in the
USA and UK.
You must agree that it pays to use
Somers Solidised Steels.
Hot Work Die & Mould Steels 2kg to 36 tonnes
Page 3
SUPPLY CONDITIONS AND
RELATED SPECIFICATIONS
Die Steel Selection
Supply Condition
An essential function of any hot work die
steel is its capacity to retain sufficient hard‐
ness at the normal elevated working temper‐
atures. When considering the working
characteristics of a die steel the user will
often base the selection of die block hard‐
ness upon the type of equipment to be used,
i.e. hammer or press.
Die blocks can be supplied black or rough
machined, dovetails sawn or finished and in
the annealed, normalised or hardened and
tempered conditions. See pages 28‐29 for
hardness conversion table.
The selected hardness of the block is invari‐
ably the subject of compromise. High hard‐
ness is best for resisting wear, but this can
lead to premature cracking, whilst if the
hardness of the die block is too low it will
rapidly erode under working conditions and
lack thermal stability.
Nearest Related Specifications
French
German
No. 5 Electem
55NDCV07‐03
1.2713
Somdie
55NDCV07‐05
1.2714
Thermodie
55NDCV08
Grain Flow
Hydie
The grain flow is normally parallel to the
length dimension but the block can be cross
forged on request, i.e. with grain flow in
width dimension.
Bestem
Japanese
SKT4
1.2307
VWMC
Z38CDWV05
1.2606
H12
VMC
Z37CDV5
1.2344
H13
1.2344
H13
Hytuf
Somers Supermold
Somplas 30
Additional factors to be considered in the se‐
lection of a die steel must include the com‐
plexity of the impression, chemical
composition of the forging stock and the
number of forgings to be produced. The fol‐
lowing pages of this brochure assist in the se‐
lection procedure, taking into account the
parameters previously mentioned. Starting
from page 8, the choice of material or range
of materials can be made. Technical and typi‐
cal composition details for the chosen mate‐
rial follow from page 14. If you require
further in‐depth technical information do not
hesitate to contact our Technical Department
and discuss your needs.
American
SKD61
P20
1.5864
3335
Markings on Somers Forge Die Block
Solidised
Trade Mark
The arms of the trade mark indicate the di‐
rection of the grain flow.
Hardness Letter
Trade Name
This indicates the type of steel used.
Production Number
A complete record is kept of all die blocks.
Page 4
Page 5
WEAR RESISTANCE OF DIE STEELS FOR
DROP FORGING
The wear resistance of a die steel depends upon the volume fraction of stable carbides pres‐
ent in the heat treated structure. The main elements which confer high wear resistance are
Molybdenum, Tungsten and Vanadium.
A good indication of the wear resistance of a given die steel may be obtained by calculating a
wear resistance factor ‘F’ from the following formula:
F = 54X + 4S
Where X = Mo + W/2 + 3V
And S = Mn + Si + Ni + Cr + Co
The wear resistance factor ‘F’ of Somers Forging die steels is shown below:
Wear Resistance
VMC
VWMC
BESTEM
HYDIE
THERMODIE
SOMDIE
ELECTEM
0
25
50
75
100
125
Wear Resistance Factor F
Page 7
SELECTION OF A HOT WORK DIE STEEL
Page 8
Page 9
MACHINABILITY
Somers Forge currently have 2 Depo CNC machine tools built to the highest
standard on the market with the capability to produce a finished mould or
die to a maximum capacity of 4.5m x 2.5m.
DEPO HC2012
3 axis horizontal machine tool, built to pro‐
duce very high metal removal rates on rough‐
ing operations.
When blocking up Die Blocks we typically use
a pentagon style face mill to the following
data:
• Cutter Diameter – 66 mm
• Surface Speed – 160m/min
• Spindle Speed – 774 rpm
• Feedrate – 1000 mm/min
• Depth of Cut – 8 mm
• Axial Cut – 40 mm
• Metal Removal Rate – 320 cm3/min
DEPO VF4525
5 axis vertical machine tool, built to provide
great flexibility with no limitations to the size
of the work piece required for machining.
The benefits of this machine are:
• Complete processing on one machine
from roughing ‐ all the way to the finishing
touches.
• The CNC programmable head makes effi‐
cient milling of even the smallest radii at
great depths possible with high precision
& finish quality in the shortest time this in
turn can eliminate or reduce the need for
spark erosion and benching.
• The ability to accurately machine under‐
cuts and angled holes to a very high accu‐
racy with ease.
• The flexibility to clamp a work piece and
machine more than one side in one
clamping operation.
Having these two machines provides Somers
Forge with the ability to dedicate the 3 axis
horizontal machine tool to heavy roughing
and the 5 axis vertical machine to carry on
further operations such as semi finishing and
finishing, also, operations requiring 3+2 axis
machining. This ensures we utilize both ma‐
chines to their maximum capabilities.
Using our high spec machine tools in con‐
junction with the latest cad/cam software
and cutting tools on the market enables
Somers Forge to produce complex work‐
pieces in the shortest possible lead time
achieving great accuracy, aiming to provide a
mould or die without any additional fitting or
benching operations.
After the blocking up process is complete,
rough machining of a 3 dimensional cavity is
commenced, typically a button style cutter is
used to the following data:
• Cutter Diameter – 66 mm
• Surface Speed – 160 m/min
• Spindle Speed – 774 rpm
• Feedrate – 2000 mm/min
• Depth of Cut – 3 mm
• Axial Cut – 40 mm
• Metal Removal Rate – 300 cm3/min
Using these 2 cutters we are able to block up
and rough out a complex work piece in a very
short time.
Page 10
Page 11
No. 5 ELECTEM
SOMDIE
Ni‐Cr‐Mo Die Steel
• Recommended as the standard die block
steel.
• Water / oil quenched tempered die steel.
C
Si
Mn
Ni
Cr
Mo
V
0.55
0.30
0.80
1.40
0.90
0.35
0.07
Page 14
• This die steel is recommended where ad‐
ditional toughness is required in a general
purpose die block.
• Oil quenched and double tempered.
• Developed for additional toughness and
hardenability.
• Recommended for medium to long term
die runs.
• Normally supplied oil quenched and dou‐
ble tempered.
C
Si
Mn
Ni
Cr
Mo
V
0.55
0.30
0.85
1.60
1.20
0.50
0.10
Typical analysis %
• Can be supplied to a maximum hardness
of 477 BHN depending on the size of block
and impression depth.
• Recommended pre‐heat temperature
200°C (392°F) min.
550
Brinell Hardness Number
This tempering graph indicates the approxi‐
mate range of hardness expected following
heat treatment. The upper and lower limits
are indicated but hardness may vary, being
dependent on bulk of material, chemical
analysis, soaking time and temperature dur‐
ing hardening and subsequent tempering
time.
High Grade Die Steel
Typical analysis %
• Normally supplied in the OH&T condition
to a hardness range specified by the cus‐
tomer.
• Supplied annealed for hardening and tem‐
pering after sinking of impression by the
customer, or hardened and tempered to
suit customer requirements.
200°C (392°F) min.
Tempering Curve No.5 Electem
A Superior Ni‐Cr‐Mo‐V
General Purpose Die Steel
°C
°F
550
450
Typical analysis %
SOMTHERM
350
250
400
750
500
930
600
1110
700
1290
°C
°F
450
0.55
0.30
1.00
2.00
1.10
0.75
0.10
• Can be supplied to a maximum hardness
of 477 BHN depending on the size of block
and impression depth.
200°C (392°F) min.
Tempering Curve
Somdie and Somtherm
350
400
750
C
Si
Mn
Ni
Cr
Mo
V
500
930
600
1110
700
1290
time.
Page 15
THERMODIE
HYDIE
Hot Work Die and Insert Steel
Special Die and Insert Steel
• Recommended for all types of hot work
applications including long‐run dies, in‐
serts, gripping dies, rolls, punches, stems
and liners for aluminium extrusion
processes.
• Recommended for use as a general pur‐
pose die steel on hammers or as press in‐
serts.
Typical analysis %
C
Si
Mn
Ni
Cr
Mo
Typical analysis %
0.55
0.55
0.60
2.00
0.90
0.75
C
Mn
Ni
Cr
Mo
V
0.37
0.60
0.30
3.00
0.80
0.20
• This die steel offers extremely good wear
resistance and retains a good hardness at
elevated temperatures.
• Supplied hardened and double tempered
or annealed.
• Can be nitrided.
200°C (392°F).
• Supplied hardened and tempered or an‐
nealed.
200°C (392°F) min.
550
Tempering Curve Thermodie
time.
Page 16
550
Tempering Curve Hydie
500
450
400
350
300
°C
°F
0
33
100
212
200
390
300
570
400
750
500
930
600
1110
700
1290
time.
600
°C
°F
450
350
400
750
500
930
600
1110
700
1290
Page 17
BESTEM
VWMC
Nickel‐Molybdenum‐Chromium Die Steel
Special Hot Work Steel
• Hot work die steel suitable for mechanical
forging press inserts and upset forging ma‐
chine dies and punches.
• Recommended for dies, inserts, punches
etc. with mechanical and friction screw
presses, also horizontal upsetters. Applica‐
tions in hot brass pressing and forging
high nickel alloys.
• Precipitation hardening die steel.
• Supplied hardened to 341 / 388 BHN for
immediate us or annealed to 302 BHN
max.
• To harden, air cool from 1000 – 1020°C
(1832 – 1870°F) followed by tempering.
Owing to precipitation effects, tempering
increases the hardness at approximately
570°C (1060°F) beyond which the hard‐
ness falls rapidly. Please consult our tech‐
nical department for the optimum
tempering temperature for the desired
hardness. It should be emphasised that up
to this limit tempering has the reverse ef‐
fect to that of normal steel because
Bestem is relatively soft as quenched and
increases in hardness as the tempering
temperature is raised.
• The time for tempering is also a factor, at
least 1 hour per 25mm (1”) of thickness
must be allowed.
150°C (302°F) min.
Page 18
Typical analysis %
Tempering Curve Bestem
This temperature graph indicated the approx‐
imate range of hardness expected following
time.
C
Si
Mn
W
Cr
Mo
V
0.34
1.00
0.29
1.50
5.00
1.50
0.50
• This steel is normally supplied in the an‐
nealed condition to 241 BHN max.
• To harden, pre‐heat to 850°C (1560°F)
then heat quickly to 1030 – 1050°C (1886
– 1922°F) but do not unduly soak, cool in
air. Large sections should be oil quenched
or martempered.
• Tempering to follow immediately after
hardening for 1 hour per 25mm (1”) of
thickness. Double temper to suit require‐
ments.
• A second tempering should only be car‐
ried out after the block has cooled to am‐
bient temperature and is recommended
where maximum toughness and resist‐
ance to heat checking is desired.
• Tempering in a controlled atmosphere will
be found advantageous.
• Where maximum abrasion resistance is re‐
quired nitriding is recommended.
150 – 350°C (302 – 662°F).
Tempering Curve VWMC
time.
Page 19
VMC (H13)
HYTUF
VMC & HYTUF
Cr‐Mo‐V Hot Work Die Steel
A Superior Hot Work Tool Steel
Heat Treatment
• Recommended for die inserts on mechani‐
cal friction screw presses and horizontal
forging machines, additionally for use in
aluminium die casting, extrusion
processes and plastic moulds.
• Somers premium grade H13.
• Manufactured by special clean steel melt‐
ing route, with very low sulphur levels to
achieve maximum toughness in service.
• Recommended for die inserts, extrusion
tools, plastic moulds and die casting in‐
serts and cores.
• It is particularly suitable for severe duties.
These steels can be supplied in the hardened and tempered condition but they are normally
supplied annealed to 241 BHN max. Further treatment by the customer after die sinking
would be as follows.
Typical analysis %
C
Si
Mn
Cr
Mo
V
0.37
1.00
0.50
5.00
1.50
1.00
150 – 350°C (302 – 662°F).
Typical analysis %
C
Si
Cr
Mo
V
0.37
1.00
5.30
1.40
1.00
150 – 350°C (302 – 662°F).
Annealing
Heat slowly to 820 – 850°C (1510 – 1560°F). Cool in furnace at not more than 10°C (50°F) per
hour to 600 – 650°C (1110 – 1200°F). Should this cooling rate be exceeded the furnace tem‐
perature should be held at 720°C (1330°F) for 4 – 6 hours prior to further cooling.
Stress Relieving
Where dies have been heavily machined it is advisable to stabilise at 650°C (1200°F) in order
to relieve stresses prior to further machining and hardening and tempering operations.
Hardening
The use of a protective furnace atmosphere (vacuum furnace) is required to prevent exces‐
sive oxidisation and carburisation or decarburisation during austenitising, which could affect
the properties of the steel.
Oil or grease should also be removed from the die surface. Pre‐heat to 820 – 850°C (1510 –
1560°F) then heat quickly to 1000 – 1050°C (1830 – 1920°F) but do not soak unduly. Cool in
vacuum or air.
Tempering Curve VMC and Hytuf
time.
Page 20
Tempering
Temper immediately after hardening for 1 hour per 25mm (1”) of thickness. Double temper
to suit requirements. The second tempering should only be carried out after the block has
cooled to ambient temperature and is recommended where Nitriding
The surface can be hardened by gaseous or plasma process to give approximately 950 to
1100 Vickers hardness number. Nitriding cycles of between 10 – 30 hours are normally em‐
ployed or the shorter Tufftriding process can be used.
Page 21
SUPAMOLD
SOMPLAS 30
High Finish Plastic Mould Steel (835 M30 Type)
Special Plastic Mould Steel (AISI P20 Type)
• Recommended for all types of plastic
moulds.
• Recommended for plastic moulds and zinc
die‐casting dies.
Typical analysis %
Typical analysis %
C
Mn
Ni
Cr
Mo
0.32
0.500
4.25
1.25
0.30
• A high grade steel suitable for both pres‐
sure and injection plastic moulds.
• Specially recommended when high polish
is required.
• An air hardened steel with minimum dis‐
tortion.
• Easily machinable in the annealed state.
• Further treatment by customer after die
sinking as follows:
Tempering curve Somplas 30
time.
C
Mn
Si
Cr
Mo
0.35
0.80
0.30
1.50
0.40
• Supplied in the pre‐hardened condition at
approximately 300 BHN.
• Readily machinable and can be polished to
a mirror finish.
• Suitable for photo‐etching or texturing.
Tempering Curve Somers Supamold
time.
Hardening
Equalise at 620°C (1150°F), then heat quickly
to 820°C (1510°F), soaking up to one hour
per 25mm (1”) of minimum dimension, cool
in air or oil quench.
Tempering
To follow immediately after hardening for 1
hour per 25mm (1” of thickness).
Page 22
Page 23
FRACTURE & NOTCH TOUGHNESS CURVES
Fracture Toughness
Notch Toughness
Application of fracture mechanics at elevated temperature has shown that steels with im‐
proved wear resistance need not necessarily be more prone to premature fracture.
Charpy impact valves are a measure of the resistance to brittle fracture under shockloading
conditions. Pre‐heating is important for optimum toughness.
Testing of two die steels has shown the difference if their fracture toughness, and the superi‐
ority of the more wear resistant material when die pre‐heating temperatures are maintained
within specific limits.
Page 24
No. 5 Electem
Hydie
Ideal
Die Working
Temperature
Ideal
Die Working
Temperature
Page 25
HOT TENSILE PROPERTIES OF SELECTED
DIE STEELS
THERMAL FATIGUE RESISTANCE CURVES
Thermal Fatigue Resistance Curves
Electem
Hardness at Room Temperature
VMC
The development of cyclic thermal fatigue cracking is one of the causes of reduced die life.
Cracks of a shallow nature, resulting from thermal fatigue, often do not significantly affect the
performance of a die and many thousands of forgings may be produced long after surface
cracks have been introduced. Cracks resulting from mechanical fatigue, and thermal fatigue
cracks, extended by hot metal being forced into the crack opening, can often extend beyond
economical limits of re‐machining or may propagate in a rapid manner, resulting in the com‐
plete breakage of a die block.
363 / 388 BHN
46 / 47 Rockwell ‘C’ = 429 / 444 BHN
Graph ‘A’ shows the growth of thermal fatigue cracks in die steels subjected to repetitive
heating and cooling cycles shown in Graph ‘B’.
Temperature of test °C
300
400
500
72.0
59.9
51.2
55.5
52.8
50.0
46.6
47.8
44.8
41.6
37.4
40.6
37.4
34.2
30.2
29.0
18.9
16.5
18.5
20.1
47.2
64.0
75.2
500
78.5
65.8
65.0
60.8
55.2
49.4
54.9
48.9
42.2
34.9
Tensile strength, ton/in²
Proof stress, ton/in²
0.2%
0.1%
0.05%
0.02%
400
Limit of proportionality, ton/in²
40.0
0.2%
0.1%
0.05%
0.02%
Elongation % on 5.65 √A
Reduction of area %
Graph A
Page 26
Graph B
Somdie
VWMC
363 / 388 BHN
51 / 52 Rockwell ‘C’ = 495 / 514 BHN
R.T.
200
300
400
Yield stress, ton / in²
76.0
–
–
–
Proof stress, ton / in²
–
68.0
65.6
61.6
Tensile strength, ton / in²
80.0
78.5
77.2
68.0
Elongation % on 5.65 √A
15.0
13.2
15.0
17.0
Reduction of area %
54.4
57.6
69.6
400
500
600
92.0
78.0
53.9
77.2
70.2
61.6
49.7
63.7
56.8
49.6
39.7
41.3
36.4
31.4
26.0
Limit of probability, ton / in²
27.2
23.8
16.0
51.0
0.2%
0.1%
0.05%
0.02%
Page 27
HARDNESS CONVERSION TABLE SHOWING STANDARD HARDNESS RANGES OF HEAT TREATED DIE BLOCKS
Page 28
Page 29
STRESS CONVERSION TABLE
Page 30
METRIC CONVERSION TABLE
TEMPERATURE CONVERSION TABLE
Page 31
A FOLKES HOLDING COMPANY
Somers Forge Ltd.
Haywood Forge, Prospect Road
Halesowen, West Midlands
B62 8DZ, ENGLAND
Tel: (+44) 0121 585 5959
Fax: (+44) 0121 585 6699
Email: [email protected]
Export Sales: [email protected]
Web: www.somersforge.com
Somers Steelstock
Haywood Forge, Prospect Road
Halesowen, West Midlands
B62 8DZ, ENGLAND
Tel: (+44) 0121 585 5959
Fax: (+44) 0121 585 2929
Web: www.somersforge.com
Somers Steel (USA)
6221 Commerce Drive
Westland, Michigan
MI 48185‐7630, USA
Tel: 734‐729‐3700
Toll free in USA: (1) 800‐854‐2927
Fax: 734‐729‐4130
BS EN 9100
BS EN ISO 9001

Die Steel Handbook

Transcription

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