Matrix High Speed
3
P owder metallurgy offers significant advantages over traditionally melt- ed cold-work and high-speed steels. The ability to produce highly alloyed steels free of segregation, with uniform grain structure and carbide distribu- tion, allows powdered-steel producers to make claims about their steels’ high performance. If your problems revolve around pure abrasive wear, many of these claims prove true. Looking Beyond Abrasive Wear In the Japanese tooling industry, it has long been accepted that abrasive wear is not always the cause of prema- ture tool failure. Often, fracturing, chip- ping and microchipping—popping of individual or groups of carbides from a cutting surface—are the culprits. Japan- ese end-users sought a lower-cost mate- rial that could address all toughness Tooling Technology Matrix High- Speed Steels Economical Alternative to Powders If fracturing, chipping and microchipping plague your tooling, consider using a new breed of tool steel. BY TOM SCHADE Tom Schade is vice president of Interna- tional Mold Steel, Florence, KY; tel. 800/625-6653; www.imsteel.com. 48 METALFORMING / MAY 2004 www.metalformingmagazine.com Applications MDS1 MDS3 MDS7 MDS9 Punch • • • • Trimming die • • Bending/drawing die • • • • Shear blades • Blanking die • • • Slitter knife • • • Roll • • • Woodwork knife • • • Heading die • • Rolling die • • • Warm-forming die • Applications for Matrix High-Speed Steels and fatigue problems, so the Japanese specialty-steel industry searched for a class of wrought alloys to do just that. The research efforts of Nachi- Fujikoshi Corp, Daido Steel Ltd and others resulted in a new series of matrix high-speed steels. As is common in Japan, these steels are not classified by AISI or JIS standards. Each producer markets its variation under a trade name. Nachi has the MDS series, MDS1, MDS3, MDS7 (matrix high-speed) and MDS9 (high-toughness cold-work). Daido has MH85, MH88 (matrix high-
Transcript of Matrix High Speed
Powder metallurgy offers significantadvantages over traditionally melt-ed cold-work and high-speed steels.
The ability to produce highly alloyedsteels free of segregation, with uniformgrain structure and carbide distribu-tion, allows powdered-steel producers tomake claims about their steels’ highperformance. If your problems revolvearound pure abrasive wear, many ofthese claims prove true.
Looking Beyond Abrasive WearIn the Japanese tooling industry, it
has long been accepted that abrasivewear is not always the cause of prema-ture tool failure. Often, fracturing, chip-ping and microchipping—popping ofindividual or groups of carbides from acutting surface—are the culprits. Japan-ese end-users sought a lower-cost mate-rial that could address all toughness
Tooling Technology
Matrix High-Speed SteelsEconomical Alternative to PowdersIf fracturing, chipping and microchippingplague your tooling, consider using a new breed of tool steel.
BY TOM SCHADE
Tom Schade is vice president of Interna-tional Mold Steel, Florence, KY; tel.800/625-6653; www.imsteel.com.
48 METALFORMING / MAY 2004 w w w . m e t a l f o r m i n g m a g a z i n e . c o m
Applications MDS1 MDS3 MDS7 MDS9
Punch • • • •Trimming die • •Bending/drawing die • • • •Shear blades •Blanking die • • •Slitter knife • • •Roll • • •Woodwork knife • • •Heading die • •Rolling die • • •Warm-forming die •
Applications for Matrix High-Speed Steels
and fatigue problems, so the Japanesespecialty-steel industry searched for aclass of wrought alloys to do just that.
The research efforts of Nachi-Fujikoshi Corp, Daido Steel Ltd andothers resulted in a new series of matrixhigh-speed steels. As is common in
Japan, these steels are not classified byAISI or JIS standards. Each producermarkets its variation under a tradename. Nachi has the MDS series, MDS1,MDS3, MDS7 (matrix high-speed) andMDS9 (high-toughness cold-work).Daido has MH85, MH88 (matrix high-
speed) and DC53 (high-toughness cold-work die steel).
Carbide Size and QuantityLimit Effectiveness
Consider D2, a low-cost high-hard-enability cold-work die steel. Large car-bide particles and lack of toughnesscan limit the life of tools made from D2in certain applications, and the largecarbide particles also compromisemachinability and grindability. In the1980s, Japanese researchers realized thatby lowering alloying elements andincreased hot-working grain refine-ment, they could produce super-toughfine-grained cold-work die steels withadvantages over D2. Thirty-percentimprovement in machinability andgrindability, improvements in impactand fatigue strength, and higher hard-enability at high draw temperaturescaused the Japanese tool industry togravitate to these steels throughout the1990s.
The Japanese specialty-steel industrythen shifted its focus to overcomingthe inherent low-fracture resistance ofhigh-speed and powdered steels. Thepremise behind development of matrixhigh-speed steels: Carbides were theproblem, not the solution. Developersalready had shown with the high-tough-ness cold-work materials that reduc-ing the size and quantity of carbides had
Charpy Impact Value of MDS Series, M2 and D2
150
100
50
0
Char
py im
pact
val
ue (J
/cm
2 )
MDS1
MDS3
MDS7MDS9
D2M2
Specimen: 5 x 10 x 5mm (no-notch)
55 60 65Hardness (HRC)
Deflective Strength of MDS Series, M2 and D2
6
5
4
3
2
Bend
ing
stre
ngth
(kN/
mm
2 )
MDS1 MDS3
MDS7
MDS9
D2
M2
55 60 65Hardness (HRC)
6
5
4
3
2
1
0Tran
sver
se ru
ptur
e st
reng
th(K
N/m
m2 )
Transverse Rupture Strength
MDS1 MDS3 MDS7 PM HSS60HRC 62HRC 64HRC 62HRC
100
80
60
40
20
0Char
py im
pact
val
ue (J
/cm
2 )
Charpy Impact Value
MDS1 MDS3 MDS7 PM HSS59HRC 62HRC 64HRC 60HRC
Fig. 1 Fig. 2
Fig. 4
Fig. 3
w w w . m e t a l f o r m i n g m a g a z i n e . c o m METALFORMING / MAY 2004 49
GradeHeattreatment temp. (C) Standard
hardness(HRC)Austenitizing Tempering
MDS1 1100-1150 560-640 56-58
MDS3 1080-1160 540-600 60-64
MDS7 1100-1180 540-600 62-66
MDS9DC53 1020-1050 180-200
500-56058-6260-64
Table 1—Heattreatment Characteristics of MDS Series
Tooling TechnologyGrindability
Grin
dabi
lity
(wei
ght l
oss
of s
peci
men
/wei
ght l
oss
of g
rindi
ng w
heel
)
3
2
1
0
Cutting depth: 0.05 mmPeripheral speed: 2000 rpm
MDS1 MDS3 MDS7 MDS9 M2 D258 63 65 62 65 62
Hardness (HRC)
benefits. With matrix high-speed steels, alloy ele-ments are resubjected to a solid-solution treatmentwith a base (matrix), reducing the quantity of car-bides. The end result offers high toughness and frac-ture resistance. Additional benefits include improvedmachinability and grindability. The trade off isreduced abrasive wear when compared to M2 orpowdered steels.
Characteristics DefinedToughness—Matrix high-speed tool steel exhibits
high toughness and fracture resistance due to the spe-cial characteristics of its microstructure. Fig. 1 showsthe Charpy impact value of the MDS series and Fig. 2 shows its deflective strength. When the Charpyimpact value is compared at the same hardness, thevalue is higher for matrix high-speed steel than forM2 or D2. The same can be said for deflectivestrength. Figs. 3 and 4 show similar results when thematrix formula is compared to high-vanadium (10)powdered high-speed steel. This underscores theretention of the matrix steel’s wear resistance andimproved fracture resistance.
Machinability—Benefits due to fine grain struc-ture and reduced carbides in matrix high-speedsteels include improved machinability and grindingafter heattreatment. Fig. 5 compares the grindingratio (test-piece weight reduction divided by grind-ing-wheel weight reduction) as the indicator ofgrindability—a higher ratio indicates improvedgrindability. Reduced machining and grinding costssignificantly reduce tool costs.
Heattreatment—Matrix high-speed steels areless sensitive than other high-speed steels to theslower cooling rate of vacuum heattreat furnaces. Forexample, the center hardness of an M2 100-mm barloses three points of HRC as a result of slower vac-uum-furnace cooling. Matrix high-speed steels donot lose HRC points. Table 1 shows austenitizing andtemper temperature ranges as well as expected hard-ness ranges for MDS steels
Wear Resistance—Cold-work die steels offer awide hardness range, extending from HRC 58 toHRC 65. Matrix high-speed formulations containsteels with differing wear-resistance levels. For exam-ple, the hardness for one is HRC 58, and HRC 62-64for another. These levels are controlled by the quan-tity of the matrix. The results of this control can beseen in Fig. 6, where a lower wear ratio indicatessuperior wear resistance. Fig. 7 compares abrasivewear resistance to high-vanadium (10) powdered-metal high-speed steel.. MF Fig. 7
50 METALFORMING / MAY 2004 w w w . m e t a l f o r m i n g m a g a z i n e . c o m
10-3
10-4
10-5Wea
r rat
io (m
m3 /
(m *
kg))
2.86
0.46
Friction speed (m/sec)
MDS1 MDS3 MDS7 MDS9 M2 D258 63 65 62 65 62
Hardness (HCR)
Wear Resistance
3
2
1
0Abra
sive
ness
(mm
3 /(m
*kg
))
Wear Resistance Compared to Powdered-MetalHigh-Speed Steel (PM HSS)
MDS1 MDS3 MDS7 PM HSS58HRC 63HRC 65HRC 62HRC
Fig. 6
Fig. 5
