BOEHLER M314
EXTRA
SAMPLE
Filing Code:
Stainless Steel
SS-987
February 2007
(NOT FOR DISTRIBUTION)
BOEHLER M314 EXTRA
(Tempered Turbine Blade Steel)
Böhler M314 Extra is free machining with high sulfur, prehardened, and corrosion resistant with 16% Cr. It is used as holder frames for plastic mold
tooling.
Chemical Composition, wt.%:
(Average)
Carbon
Silicon
Manganese
Sodium
Chromium
Molybdenum
Iron
Physical Properties:
0.34
0.35
1.40
0.12
16.0
0.15
bal
SAMPLE
Quenching should be as rapid as possible to avoid unwanted transformation products. Complex geometries and thick cross sections
may require an interrupted quench procedure (step or marquenching/
martempering) to prevent excessive distortion and/or cracking.
Regardless of the quenching process the tooling must be tempered
after reaching 65 °C (150 °F).
(NOT FOR DISTRIBUTION)
Density, kg/m3 (lb/in.3)
Thermal conductivity, 20 °C (68 °F),
W/m · K (Btu/(ft · h · °F))
Specific heat capacity, 20 °C (68 °F),
J/kg · K (Btu/lb · °F)
Resistivity, 20 °C (68 °F), μΩ · m
(Ω circular-mil/ft)
Coefficient of linear thermal expansion,
10−6/K (10−6/°F)
20-100 °C (68-212 °F)
20-200 °C (68-392 °F)
20-300 °C (68-572 °F)
20-400 °C (68-752 °F)
20-500 °C (68-932 °F)
Mechanical Properties:
7650 (0.276)
18.00 (10.4)
460 (0.110)
Tempering. Select the tempering temperature from the tempering
curve based on the hardness requirements. A minimum of two
tempers with intermittent cooling to room temperature is required.
Holding time at temperature for a minimum of 2 h is recommended
for each tempering cycle (see Fig. 1).
0.65 (390)
Machinability:
11.0 (6.1)
11.1 (6.1)
11.2 (6.2)
11.6 (6.4)
12.0 (6.6)
Table 1 shows turning and milling data recommendations on annealed
material. Additional milling, drilling data is available from the
producer.
SAMPLE
Modulus of elasticity, 20 °C (68 °F),
GPa (106 psi)
Heat Treatment:
Hardening. The tool must be held in a protective atmosphere
throughout the hardening process. Use a preheat temperature of
500-600 °C (930-1110 °F) and austenitizing/hardening temperature
of 1000-1050 °C (1830-1920 °F). The steel should be heated through
to the appropriate hardening temperature and then held at this
temperature for 30 min. The soak time is measured from the point at
which the core of the block has reached the designated temperature.
212 (30.7)
(NOT FOR DISTRIBUTION)
M314 Extra is intended to be used in the as-delivered condition, that
is, hardened and tempered to approximately 300 HB. If this needs to
be adjusted, the steel must first be soft annealed and then heat treated
according to the recommendations listed below. Note that the tool
must be protected from decarburization and/or oxidation during the
heat treating process.
Soft Annealing. The steel must be held in a protective atmosphere
up to a temperature of 860 °C (1580 °F). After reaching this annealing
temperature, the steel must be cooled slowly at a rate of 20 °C/h (35
°F/h) down to 650 °C (1200 °F). Subsequent cooling can be completed
freely in air.
Fig. 1 Tempering chart. Hardening: holding time 30 min in oil;
tempering 2 × 2 h; specimen size 20 × 20 mm square
Table 1
Recommendation for Machining
Depth of cut
mm
in.
Feed
Cutting speed
m/min
fpm
SAMPLE
mm/rev
in./rev
Tool
Edge life, min
Rake angle
Clearance angle
Angle of inclination
Turning with carbide-tipped tools, indexable inserts
0.5-1
0.02-0.04
0.1-0.2
0.004-0.016
1-4
0.04-0.16
0.2-0.4
0.008-0.016
4-8
0.16-0.31
0.3-0.6
0.012-0.024
US grade C6, C7;
ISO grade P10, P20, M10
US grade C6;
ISO grade P20, M10, M20
US grade C5, C3;
ISO grade P30, M20, K10
200-260
655-850
15
···
···
···
150-200
490-655
15
···
···
···
110-150
360-490
15
···
···
···
US grade C6, C7;
ISO grade P10, P20, M10
US grade C6;
ISO grade P20, M10, M20
US grade C5, C3;
ISO grade P30, M20, K10
170-210
560-690
30
12-15°
6-8°
0°
130-170
425-560
30
12-15°
6-8°
0°
90-140
295-460
30
12-15°
6-8°
-4°
AISI T42; DIN S10-4-3-10
AISI T42; DIN S10-4-3-10
AISI T42; DIN S10-4-3-10
45-55
35-45
25-35
150-180
115-150
80-115
60
60
60
14-18°
14-18°
14-18°
8-10°
8-10°
8-10°
0°
0°
0°
(NOT FOR DISTRIBUTION)
Turning with carbide-tipped tools, brazed tools
0.5-1
0.02-0.04
0.1-0.2
0.004-0.016
1-4
0.04-0.16
0.2-0.4
0.008-0.016
4-8
0.16-0.31
0.3-0.6
0.012-0.024
Turning with high-speed steel (HSS) tools
0.5
3
6
0.02
0.12
0.24
0.1
0.5
1.0
0.004
0.002
0.04
Annealed condition. Average hardness 300 HB
The chemical composition of M314 Extra has been adjusted to
provide for improved corrosion resistance. The ability to resist
corrosive attack results in cooling channels that are less likely to be
affected by corrosion resulting in consistent cycle times over the life
of the mold, and resistance to attack from corrosive by-products and
vapors, providing for easier operation and mold storage.
SAMPLE
Product Forms Available:
(NOT FOR DISTRIBUTION)
Rectangular cross-sections pieces are available from 5 8 to 10 in. in
thickness with widths from 10-60 in. Bar is available as ground,
machined, and peeled for different sizes. Contact the producer.
Applications:
Fig. 2 Corrosion-resistant surface area after performance of the saltspray test (DIN 50021) on hardened and tempered steels. Hardness
approximately 32 HRC
Holder/mold frames, backing plates, and bolsters for plastic mold
tooling; structural components and fixtures that required corrosion
resistance; tooling for plastics extrusion; and rubber molding and
other plastics molding applications where polishability is not a priority.
Corrosion Resistance:
The corrosion-resistant surface area after performance of the saltspray test (DIN 50021) on hardened and tempered steels is shown
in Fig. 2 in a comparison to similar grades.
General Characteristics:
Producer:
Bohler-Uddeholm North America
Rolling Meadows, IL 60008
(800) 638-2520
(905) 812-8659 (fax)
www.bucorp.com
SAMPLE
Böhler M314 Extra is a free-machining stainless steel that has been
developed specifically for the plastics molding industry. It is supplied
in the prehardened condition at a hardness level of approximately
300 HB. The balanced chemical composition and specialized heat
treatment results in lower mold production costs due to improved
machinability, uniform hardness levels throughout the cross section,
good dimensional stability during machining, and a high level of
corrosion resistance.
In Austria
Bohler Edelstahl GmbH & Co KG
A-8605 Kapfenberg, Austria
+43-3862/20-7181
+43-3862/20-7576 (fax)
www.bohler-edelstahl.at
(NOT FOR DISTRIBUTION)
A benefit to the mold builder is a reduction in mold production
costs, due to less tool wear experienced during machining operations
and the option to use increased cutting speeds.
ISSN: 002-614X
SS-987B