The name

you can
trust

HOT WORK TOOL STEEL

RAVNEX DC
 RAVNEX DC
CONTENTS GENERAL CHARACTERISTICS 02
Chemical composition
Application
Microstructure in delivered condition
Toughness
Qualitative comparison

PHYSICAL PROPERTIES 05

MECHANICAL PROPERTIES 06
Impact toughness at elevated temperatures

CONTINIOUS COOLING CURVES-CCT 07

HEAT TREATMENT 08
Annealing
Stress relieving
Hardening
Tempering
Dimensional changes during hardening
and tempering

SURFACE TREATMENT 10
Nitriding and nitrocarburising

WELDING AND EDM 11

Welding
Electrical discharge machining

RECOMMENDATIONS FOR MACHINING 12

CASE STUDY 13
M E T A L R A V N E • T h e n a m e y o u c a n t r u s t

GENERAL CHARACTERISTICS

RAVNEX DC is a supreme hot-work tool steel

produced in METAL RAVNE, known for:

• High impact toughness

• High hot tensile properties and high working hardness
• High thermal conductivity
• Good polishability
• Nitrability
• High cleanliness
• Longer tool life
• Excellent homogeneity
• Weldability

CHEMICAL COMPOSITION (%)

METAL AISI W .Nr . C Si Mn Cr Mo V

RAVNEX DC H11 mod ~1.2343 0.36 0.20 0.30 5.00 1.35 0.45

Chemical element content is in wt.%

APPLICATION

RAVNEX DC is primarily designed for die casting of light metals and alloys. It is often used for highly stressed
hot-work structural parts where superior toughness is required (up to average Charpy V-notch value of 29.8 Joule
at 44-46 HRC according to NADCA#207).

RAVNEX DC is also recommended for die forging and extrusion. Because of its good polishability,
the grade can be used for plastic molding applications and processing of glass.

RAVNEX DC is supplied in annealed condition, max. 209 HBW (705 N/mm2).

02
T h e n a m e y o u c a n t r u s t • M E T A L R A V N E

MICROSTRUCTURE IN DELIVERED CONDITION

RAVNEX DC is inspected in soft annealed condition according to SEP 1614 (Stahl-Eisen-Prüfblatt

SEP 1614 - September 1996), and according to NADCA#207 standard.

Cleanliness according to DIN 50602 is K1≤10.

Accepted rating charts of annealed RAVNEX DC.

> TAB 1: MICROHOMOGENEITY

Premium quality Standard quality Not acceptable
SA SB SC SD SE
Increasing Reduction Ratio

Increasing Degree of Segregation 50x

> TAB 2: ACCEPTABILITY CRITERIA OF ANNEALED MICROSTRUCTURE ACCORDING TO NADCA #207-2003

All microstructures etched with 5% Nital RAVNEX DC
Acceptable Unacceptable annealed

500x

03
M E T A L R A V N E • T h e n a m e y o u c a n t r u s t

TOUGHNESS

Un-notched specimens (7 x 10 x 55 mm3) are used to test impact toughness in transverse direction,
SEP 1314 (Stahl-Eisen-Prüfblatt SEP 1314- April 1990). Specimens are quenched and tempered to 45 +/- 2 HRC,
and test is performed at 20 °C.

Average impact toughness of forged quality is higher than 299 Joule for average forging size of 900 x 400 mm.

400 DGM (Deutsche Gesellschaft für

RAVNEX DC Materialkunde) recommends
impact toughness of minimum
250 Joules for hot-work tool steel
in various hot-work applications.
300
Impact toughness (Joule)

W.Nr. 1.2343
DGM

200

100

0
44-46 HRC

QUALITATIVE COMPARISON

RAVNEX DC is a premium tool steel of highest toughness produced in Metal Ravne.

Chart shows its toughness at high temperature compared to 1.2343 and conventional W.Nr1.2344 hot-work tool steel.

RS GRADE STRENGTH TOUGHNESS STRENGTH means ultimate

tensile strength derived from an
engineering stress-strain curve.
W.Nr.1.2343
TOUGHNESS is estimated by
reduction in cross-section area
of tensile test probe at rupture.
W.Nr.1.2344

RAVNEX DC

04
T h e n a m e y o u c a n t r u s t • M E T A L R A V N E

PHYSICAL PROPERTIES

PHYSICAL PROPERTIES (TEMPERATURE DEPENDENTS)

D E N S I T Y ( g / c m 3)

7.85 (20 °C) 7.80 (450 °C) 7.69 (500 °C) 7.67 (550 °C) 7.65 (600 °C)

THERMAL CONDUCTIVITY (W/(m.K))

28.40 (100 °C) 30.1 (450 °C) 30 (500 °C) 29.90 (550 °C) 29.70 (600 °C)

E L E C T R I C R E S I S T I V I T Y ( O h m . m m 2/ m )

0.50 (20 °C) 0.68 (450 °C) 0.86 (500 °C) 0.90 (550 °C) 0.96 (600 °C)

SPECIFIC HEAT CAPACITY (J/(g.K))

0.46 (20 °C) 0.51 (450 °C) 0.55 (500 °C) 0.57 (550 °C) 0.59 (600 °C)

M O D U L U S O F E L A S T I C I T Y ( 1 0 3 x N / m m 2)

215 (20 °C) 185 (450 °C) 176 (500 °C) 171 (550 °C) 165 (600 °C)

C O E F F I C I E N T O F L I N E A R T H E R M A L E X P A N S I O N ( 1 0 -6 ° C -1, 2 0 ° C ) *

12.40 (200 °C) 12.80 (300 °C) 13.20 (400 °C) 13.60 (500°C) 14.20 (600 °C)

* CTE is the mean coefficient of thermal expansion with reference temperature of 20 °C.

05
M E T A L R A V N E • T h e n a m e y o u c a n t r u s t

MECHANICAL PROPERTIES

IMPACT TOUGHNESS AT ELEVATED TEMPERATURES

90

80
Impact toughness KV (Joule)

70

60

50

40
0 50 100 150 200 250 300 350 400 450 500 550 600
Testing temperature (° C)

Figure shows impact toughness as function of temperature.

Samples are taken from the core of a forged block in short transverse direction.
They are quenched and tempered (Q+T; 1000 °C / oil / 2x tempering) to 45 +/- 1 HRC.
Measurement: EN ISO 148: 2010

06
T h e n a m e y o u c a n t r u s t • M E T A L R A V N E

CONTINIOUS COOLING CURVES-CCT

Austenitising temperature: 990 °C; soak time: 15 min

1200
Legend:
A - Austenite
1100 K - Carbide
P - Perlite
M - Martensite
1000
B - Bainite
Ac3 = 880 °C
900

Ac1 = 805 °C
800

P+K
700
Temperature (°C)

A+K
600

2,9 °C/s 0,2 °C/s 0,043 °C/s

500

400 Ms

B+K
300
M+K

200

Hardness HV0.3

100 576 517 461

0
1 10 100 1 000 10 000 100 000
Seconds
TIME 1 2 10 20 100 1000
Minutes

1 10
Hours

QUENCH RATE SHOULD BE SUFFICIENT TO FORM PREDOMINANTLY MARTENSITIC STRUCTURE

TIP 1 WITHOUT SIGNIFICANT AMOUNT OF BAINITE. SIGNIFICANT AMOUNT OF BAINITE FAVOURS
THERMAL FATIGUE AS A LESS STABLE PHASE CONSTITUENT WITH LOWER STRENGTH.

07
M E T A L R A V N E • T h e n a m e y o u c a n t r u s t

HEAT TREATMENT

Recommendations or NADCA#207.

ANNEALING

HEATING ANNEALING TEMPERATURE COOLING

50 °C/h 800 - 850 °C 20 °C/h

Protect against oxidation, scaling and Min. 4 hours. Slow in furnace. From 600 °C air
decarburisation. cooling is possible.

STRESS RELIEVING

HEATING STRESS RELIEVING COOLING

100 °C/h 600 °C - 650 °C or 50 °C under the 20 °C/h

last tempering temperature.

Protect against oxidation Min. 3 hours. Slow and uniformly in the furnace to
and decarburisation. prevent formation of additional
residual stresses. From approximately
200 °C air cooling is possible.

HARDENING Hardness after hardening is 50-54 HRC (1680 - 1916 N/mm2).

HEATING AUSTENITISING COOLING

25 - 650 °C, 150 - 220 °C/h 980 - 1000 °C See CCT diagram
650 - 850 °C, ≤150 °C/h,
850 - 1000 °C, ≤150 °C/h

Hold in furnace at TSURFACE is measured at 15mm Fast cooling is recommended in

T = 650 °C / 850 °C underneath surface, maximum soak pressurized N2. For large dimension
until TSURFACE-TCORE ≤≤110 °C / 60 °C time is 30 min. hot-work tooling see NADCA#207 or
GM DC-9999-1Rev.18 specification.

FOR APPLICATIONS EXPOSED TO EXTREME THERMAL LOADING A PROPER HEAT TREATMENT

TIP 2 IS ESSENTIAL. TO PREVENT EXCESSIVE GRAIN GROWTH DURING AUSTENITIZATION IT IS
PREFERABLE TO LEAVE SOME OF THE CARBIDES NOT DISSOLVED.

08
T h e n a m e y o u c a n t r u s t • M E T A L R A V N E

TEMPERING

Tempering must start immediately after completion of quenching (when part reaches 90-70 °C).
Three tempering treatments are recommended. First tempering destabilizes retained austenite.
Second tempering tempers newly formed microstructure constituents.

HEATING TEMPERING TEMPERATURE COOLING

150 °C/h - 250 °C/h 1st: 520 - 530 °C Cool in air or in the furnace to
2nd: choose working hardness room temperature between
(see tempering diagram). tempering cycles.
3rd: 50 °C bellow 2nd tempering.

Protect against oxidation 1 hour per 25mm wall thickness

and decarburisation. based on the furnace temperature.
Minimum 2 hours.

60 60

55 55
Hardness (HRC)

Hardness (HRC)

50 50

45 45

25 mm/oil 25 mm/oil

40 40
200 300 400 500 600 700 500 550 600 650 700
Tempering temperature (°C) Tempering temperature (°C)

INCREASED TOUGHNESS OF THIS SPECIAL GRADE OFFERS ONE TO SELECT HIGHER WORKING
TIP 3 HARDNESS. HIGHER THERMAL CONDUCTIVITY AND HIGH TEMPERATURE STRENGTH COMPARED
TO H11 GRADE ALSO CONTRIBUTE TO ITS IMPROVED RESISTANCE TO THERMAL FATIGUE.

DIMENSIONAL CHANGES DURING HARDENING AND TEMPERING

It is recommended to leave machining allowance before hardening of minimum 0.2 % of dimension,

equal in all three directions.

09
M E T A L R A V N E • T h e n a m e y o u c a n t r u s t

SURFACE TREATMENT

NITRIDING AND NITROCARBURISING

Nitriding treatment is commonly recommended to enhance surface properties of RAVNEX DC.

Nitriding treatment for hot-work applications is performed by producing diffusion zone only ( nitriding phase) of a depth
determined by particular application requirements, and completely inhibit surface compound layer ( and nitriding phases).

Nitriding treatment for plastic-molding or cold-work applications with wear resistance requirements is performed by
producing surface compound layer of composition and thickness determined by particular application requirements.

For applications with requirement for additional surface protection, improvement of sliding properties, or improvement
of corrosion resistance, it is recommended that oxidation treatment (Fe3O4) follows the nitriding.

For details on surface preparation and setup of nitriding treatment parameters to obtain required surface properties
please consult our approved nitriding specialist.

800

700
Temperature (°C)

600

500

400

300
0 0.1 1 10
Nitriding potential

Nitriding of hot-work applications (limited or no compound layer)

Nitriding of cold-work applications (well developed compound layer)
Nitriding for intermediate surface properties

Lehrer diagram presented in figure shows the effect of two parameters:

(1) nitriding potential (a function of partial pressure of ammonia and hydrogen), and (2) temperature, on composition of
nitriding phases formed on material surface. Figure shows recommended selection of the two governing parameters for
appropriate execution of nitriding for two extreme application regimes, hot work on one hand, and cold-work on the other.

10
T h e n a m e y o u c a n t r u s t • M E T A L R A V N E

WELDING AND EDM

WELDING

RAVNEX DC is a readily weldable alloy by TIG or MMA welding processes in hardened or soft-annealed condition. Filler
metal should be of the same or similar chemical composition.

Heat treatment after welding is recommended. Annealing should be performed after welding of soft annealed parts, whereas
tempering at temperature of about 50 °C below tempering temperature should be performed after welding of hardened
and tempered parts. Laser welding is recommended for repair of smaller cracks and edges.

PREHEATING TEMPERATURE MAXIMUM INTERPASS TEMPERATURE POST WELD COOLING

320 - 350 °C 470 °C Approximately 30 °C / h to not

less than 70 °C, then tempering.

WELDING METHOD FILLER MATERIAL HARDNESS AFTER WELDING

TIG, MMA H11 ~ 50 HRC

ELECTRICAL DISCHARGE MACHINING

Electrical discharge machining (EDM) leaves a brittle surface layer due to melting and resolidification of surface material.

It is recommended to: (1) remove the resolidified layer by polishing, grinding or other mechanical methods,
and (2) temper the work-piece at temperature of about 50 °C below the tempering temperature.
Execution of tempering of re-hardened and jet untempered layer underneath the surface is critical.

11
M E T A L R A V N E • T h e n a m e y o u c a n t r u s t

RECOMENDATIONS FOR MACHINING

The information below is provided solely as a general machining guideline. It refers to material soft annealed condition.

DRILLING

INSERT DRILL DIAMETER (mm) CUTTING SPEED (m/min) FEED (mm/rev)

HSS 5 - 20 15 - 20 0.05 - 0.30

Coated HSS 5 - 20 35 - 40 0.05 - 0.30

FACE MILLING

INSERT CUTTING SPEED (m/min) FEED (mm/tooth) DEPTH OF CUT (mm)

P20-P40 c.* (rough milling) 150 - 220 0.20 - 0.40 2.00 - 4.00

P10 c.* (fine milling) 230 - 260 0.10 - 0.20 -2.00

TURNING

INSERT CUTTING SPEED (m/min) FEED (mm/rev) DEPTH OF CUT (mm)

P20-P30 c.* (rough turning) 180 - 220 0.20 - 0.40 2.00 - 4.00

P10 c.* (fine turning) 230 - 270 0.05 - 0.20 0.50 - 2.00

HSS (fine turning) 25 - 30 -0.30 -2.00

* c. = coated carbide

12
T h e n a m e y o u c a n t r u s t • M E T A L R A V N E

CASE STUDY

HEAT TREATMENT OF RAVNEX DC

Control of quenching is critical to assure dimension stability, optimum microstructure and mechanical properties of any
work-piece.

Finite element modelling of heat treatment reveals that both hardening temperature and soaking time, as well as quenching
rate strongly depend on work piece size and geometry.

> FIG 1

Figure 1 shows temperature distribution in

two workpieces of different thickness at
a given time (t), (see Figure 2) during
quenching. One can observe a hot core and a
high temperature gradient in a thick workpiece,
while a thin workpiece has at same cooling
time almost uniform temperature distribution.

13
M E T A L R A V N E • T h e n a m e y o u c a n t r u s t

> FIG 2
1100

900

800

700
Temperature (°C)

600

500

400

300

200

100

0
0 10 20 t 30 40 50 60
Time (min)
ISO-Q
A1 A2 B1 B2 C1

Figure 2 reveals temperature transient at quenching for both workpieces at two characteristic points:
(1) a point 15mm underneath the surface, and (2) the core.

> FIG 3
800

700

600

500
T (°C)

400

300

200

100

0
0 10 20 30 40 50 60
Time (min)
ISO-Q
A2 - A1 B2 - B1 B2 - C1

Figure 3 shows temperature difference between the two characteristic points for both workpieces for the same
quenching transient. An extreme temperature gradient occurs in the thick workpiece, with high risk of causing
distortion or gross cracking. Application of isothermal quenching process (see NADCA#207) is recommended
to reduce the potential detrimental effects of extreme temperature difference. A short isothermal hold reduces
significantly the temperature gradient in the thick workpiece. (See surface temperature transifnt curve
C1ISO-Q in Figure 2 and Figure 3.)
14
T h e n a m e y o u c a n t r u s t • M E T A L R A V N E

To achieve optimum material properties, heat treatment parameters should be adjusted to specific workpiece size and
geometry. Critical quench rate is needed to avoid both pearlite formation and carbide precipitation.

In order to run quenching of a particular dimension and geometry workpiece at optimum velocity it is critical to continuously
monitor temperature of both the surface and the core throughout the cycle.

> FIG 4
300

250

200
Cooling velocity (°C/min)

150

100

50

0
20 30 40 50 60 70 80 90 100 110 120
V/A (mm)

CORE SURFACE CORNER

Figure 4 shows average cooling speed between 800 and 500 °C at the core of a generalized geometry workpiece. Both geometry and size of the
workpiece is defined by its volume (V) to surface (S) ratio. Medium quenching power in a vacuum-type furnace is applied to determine the workpiece
cooling speed (6 bar N2 overpressure with medium to high gas circulation). The plot is particularly useful for determining optimum quenching
speed in workpieces where temperature at core is not possible to directly monitor by thermocouple.
SURFACE - temperature at a point 15 mm underneath the center of largest workpiece surface.
CORNER* - temperature at a point 15 mm underneath the most exposed part of workpiece.

* data presented are computed for a point 15mm underneath an angle of a cube.

SHARP EDGES ON THE TOOL IN HEAT TREATMENT SHOULD BE AVOIDED TO PREVENT GROSS CRACKING
TIP 4 OR MICRO QUENCHING CRACKS WHICH CAN LEAD TO FORMATION OF LEADING CRACKS.

15
M E T A L R A V N E • T h e n a m e y o u c a n t r u s t

Notes

16
 RAVNEX HD is produced by:

METAL RAVNE, d.o.o.

Koroπka cesta 14, 2390 Ravne na Koroπkem, Slovenia
Telephone: +386 2 870 7000, Telefax: +386 2 870 7006
E-mail: info@metalravne.com
www.metalravne.com

RAVNEX HD is distributed by:

Publisher: Ravne Steel Center • Text: Metal Ravne • Production: RD BORGIS • AD/D: XLMS • Photos: archive Metal Ravne • Print: ALE d.o.o. • June 2014
The name
you can
trust

HOT WORK TOOL STEEL

RAVNEX HD
 RAVNEX HD
CONTENTS GENERAL CHARACTERISTICS 02
Chemical composition
Application
Microstructure in delivered condition
Toughness
Qualitative comparison

PHYSICAL PROPERTIES 05

CONTINIOUS COOLING CURVES-CCT 06

HEAT TREATMENT 07
Annealing
Stress relieving
Hardening
Tempering
Dimensional changes during hardening
and tempering

HARDNESS 09

MECHANICAL PROPERTIES 09
Impact toughness at elevated temperatures

SURFACE TREATMENT 10
Nitriding and nitrocarburising

WELDING AND EDM 11

Welding
Electrical discharge machining

RECOMMENDATIONS FOR MACHINING 12

CASE STUDY 13
Heat treatment of RAVNEX HD RS 450
M E T A L R A V N E • T h e n a m e y o u c a n t r u s t

GENERAL CHARACTERISTICS

RAVNEX HD is a supreme hot-work tool steel

produced in METAL RAVNE, known for:

• Excellent impact toughness

• High hot tensile properties and high working hardness
• Excellent thermal conductivity
• Good polishability
• Excellent hardenability
• Nitrability
• High cleanliness
• Longer tool life
• Excellent homogeneity
• Weldability

CHEMICAL COMPOSITION (%)

Controlled chemical composition with minimal content of detrimental elements compared to standard steel grades.

METAL AISI W .Nr . C Si Mn Cr Mo V Ni

RAVNEX HD - - 0.37 0.25 0.43 4.90 1.60 0.59 1.60

Chemical element content is in wt.%

APPLICATION

RAVNEX HD is primarily designed for die casting of light metals and alloys. Due to its excellent hardenability
it is especially recommended for high-dimension tooling. It is often used for highly stressed hot-work structural parts
where superior toughness is required.

RAVNEX HD is also recommended for die forging and extrusion. Because of its good polishability, the grade
can be used for plastic molding applications and processing of glass.

RAVNEX HD is supplied in annealed condition, max. 235 HBW (791 N/mm2).

02
T h e n a m e y o u c a n t r u s t • M E T A L R A V N E

MICROSTRUCTURE IN DELIVERED CONDITION

RAVNEX HD is inspected in soft annealed condition according to SEP 1614 (Stahl-Eisen-Prüfblatt SEP 1614 - September
1996), and according to NADCA#207 standard.

Cleanliness according to DIN 50602 is K1≤10.

Accepted rating charts of annealed RAVNEX HD.

> TAB 1: MICROHOMOGENEITY

Premium quality Standard quality Not acceptable
SA SB SC SD SE
Increasing Reduction Ratio

Increasing Degree of Segregation 50x

> TAB 2: ACCEPTABILITY CRITERIA OF ANNEALED MICROSTRUCTURE ACCORDING TO NADCA #207-2003

All microstructures etched with 5% Nital RAVNEX HD
Acceptable Unacceptable annealed

500x
03
M E T A L R A V N E • T h e n a m e y o u c a n t r u s t

TOUGHNESS

Un-notched specimens (7 x 10 x 55 mm) are used to test impact toughness in transverse direction, SEP 1314
(Stahl-Eisen-Prüfblatt SEP 1314- April 1990). Specimens are quenched and tempered to 45 +/- 2 HRC, and test
is performed at 20°C.

Average impact toughness of forged quality is higher than 299 Joule for average forging size of 900 x 400 mm.

400 DGM (Deutsche Gesellschaft für

RAVNEX HD
Materialkunde) recommends
impact toughness of minimum
250 Joules for hot-work tool steel
300 in various hot-work applications.
Impact toughness (Joule)

W.Nr. 1.2343
DGM

200

100

0
44-46 HRC

QUALITATIVE COMPARISON

RAVNEX HD is a premium tool steel of highest toughness produced in Metal Ravne. Chart shows its impact toughness
compared to W.Nr1.2343, conventional W.Nr1.2344 hot-work tool steel and to RAVNEX DC.

RS GRADE STRENGTH TOUGHNESS STRENGTH means ultimate

tensile strength derived from an
engineering stress-strain curve.
W.Nr.1.2343

W.Nr.1.2344

RAVNEX DC

RAVNEX HD

04
T h e n a m e y o u c a n t r u s t • M E T A L R A V N E

PHYSICAL PROPERTIES

PHYSICAL PROPERTIES (TEMPERATURE DEPENDENTS)

D E N S I T Y ( g / c m 3)

7.83 (20 °C) 7.70 (450 °C) 7.68 (500 °C) 7.66 (550 °C) 7.65 (600 °C)

THERMAL CONDUCTIVITY (W/(m.K))

32.80 (100 °C) 34.30 (450 °C) 34.10 (500 °C) 33.90 (550 °C) 33.50 (600 °C)

E L E C T R I C R E S I S T I V I T Y ( O h m . m m 2/ m )

0.50 (100 °C) 0.58 (450 °C) 0.63 (500 °C) 0.68 (550 °C) 0.73 (600 °C)

SPECIFIC HEAT CAPACITY (J/(g.K))

0.44 (20 °C) 0.64 (450 °C) 0.68 (500 °C) 0.72 (550 °C) 0.83 (600 °C)

M O D U L U S O F E L A S T I C I T Y ( 1 0 3 x N / m m 2)

210 (20 °C)

C O E F F I C I E N T O F L I N E A R T H E R M A L E X P A N S I O N ( 1 0 -6 ° C -1, 2 0 ° C ) *

11.60 (200 °C) 11.80 (300 °C) 12.02 (400 °C) 12.04 (500 °C) 12.01 (600 °C)

* CTE is the mean coefficient of thermal expansion with reference temperature of 20 °C.

05
M E T A L R A V N E • T h e n a m e y o u c a n t r u s t

CONTINIOUS COOLING CUR VES-CCT

Austenitising temperature: 1030 °C; soak time: 15 min

1200
Legend:
A - Austenite
1100 K - Carbide
P - Perlite
M - Martensite
1000
B - Bainite

900 Ac3 880 °C

Ac1 790 °C
800

700 P+K
Temperature (°C)

A+K
600

500

400

Ms
B+K
300

200 M+K

100
Hardness HV10 685 655 633 479 453 161

0
1 10 100 1 000 10 000 100 000 1 000 000
Seconds
TIME 1 Minutes 10 100 1000

QUENCH RATE SHOULD BE SUFFICIENT TO FORM PREDOMINANTLY MARTENSITIC STRUCTURE

TIP 1 WITHOUT SIGNIFICANT AMOUNT OF BAINITE. SIGNIFICANT AMOUNT OF BAINITE FAVOURS
THERMAL FATIGUE AS A LESS STABLE PHASE CONSTITUENT WITH LOWER STRENGTH.

06
T h e n a m e y o u c a n t r u s t • M E T A L R A V N E

HEAT TREATMENT

Recommendations or NADCA#207.

ANNEALING

HEATING ANNEALING TEMPERATURE COOLING

50 °C/h 800 - 850 °C 20 °C/h

Protect against oxidation, scaling and Min. 4 hours. Slow in furnace. From 600 °C air
decarburisation. cooling is possible.

STRESS RELIEVING

HEATING STRESS RELIEVING COOLING

100 °C/h 650 °C or 50 °C under the last 20 °C/h

tempering temperature.

Protect against oxidation Min. 3 hours. Slow and uniformly in the furnace to
and decarburisation. prevent formation of additional
residual stresses. From approximately
200 °C air cooling is possible.

HARDENING Hardness after hardening is 56-58 HRC (2030 - 2180 N/mm2).

HEATING AUSTENITISING COOLING

25 - 650 °C, 150 - 220 °C/h 1030 - 1050 °C See CCT diagram
650 - 850 °C, ≤150 °C/h,
850 - 1030 °C, ≤150 °C/h

Hold in furnace at TSURFACE is measured at 15mm Fast cooling is recommended in

T = 650 °C / 850 °C underneath surface, maximum soak pressurized N2. For large dimension
until TSURFACE-TCORE ≤≤110 °C / 60 °C time is 30 min. hot-work tooling see NADCA#207 or
GM DC-9999-1Rev.18 specification.

FOR APPLICATIONS EXPOSED TO EXTREME THERMAL LOADING A PROPER HEAT TREATMENT

TIP 2 IS ESSENTIAL. TO PREVENT EXCESSIVE GRAIN GROWTH DURING AUSTENITIZATION IT IS
PREFERABLE TO LEAVE SOME OF THE CARBIDES NOT DISSOLVED.

07
 M E T A L R A V N E • T h e n a m e y o u c a n t r u s t

TEMPERING

Tempering must start immediately after completion of quenching (when part reaches 90-70 °C). Three tempering treatments
are recommended. First tempering destabilizes retained austenite. Second tempering tempers newly formed microstructure
constituents.

HEATING TEMPERING TEMPERATURE COOLING

150 °C/h - 250 °C/h 1st: 540 - 550 °C Cool in air or in the furnace to
2nd: choose working hardness room temperature between
(see tempering diagram). tempering cycles.
3rd: 50 °C bellow 2nd tempering.

Protect against oxidation 1 hour per 25mm wall thickness

and decarburisation. based on the furnace temperature.
Minimum 2 hours.

60 60

55 55
Hardness (HRC)

Hardness (HRC)

50 50

45 45

25 mm/oil 25 mm/oil

40 40
100 200 300 400 500 600 700 550 600 650
Tempering temperature (°C) Tempering temperature (°C)

T austenization = 1030 °C
T austenization = 1050 °C

INCREASED TOUGHNESS OF THIS SPECIAL GRADE OFFERS ONE TO SELECT HIGHER WORKING
TIP 3 HARDNESS. HIGHER THERMAL CONDUCTIVITY AND HIGH TEMPERATURE STRENGTH COMPARED
TO H11 GRADE ALSO CONTRIBUTE TO ITS IMPROVED RESISTANCE TO THERMAL FATIGUE.

DIMENSIONAL CHANGES DURING HARDENING AND TEMPERING

It is recommended to leave machining allowance before hardening of minimum 0.2 % of dimension,

equal in all three directions.

08
T h e n a m e y o u c a n t r u s t • M E T A L R A V N E

HARDNESS
TEMPERING DIAGRAM RAVNEX HD
60 1050 / 1x 2h
1050 / 2x 2h

55
Hardness (HRC)

50

45

40

25 mm/oil

35
480 500 520 540 560 580 600 620 640 660
Tempering temperature (°C)

MECHANICAL PROPERTIES
IMPACT TOUGHNESS AT ELEVATED TEMPERATURES
90

80
Impact toughness KV (Joule)

70

60

50

40

30
0 100 200 300 400 500
Tempering temperature (°C)

Figure shows impact toughness as function of temperature.

Samples are taken from the core of a forged block in short transverse direction.
They are quenched and tempered (Q+T; 1030 °C / oil / 2x tempering) to 45 +/- 1 HRC.
Measurement: EN ISO 148: 2010 09
M E T A L R A V N E • T h e n a m e y o u c a n t r u s t

SURFACE TREATMENT

NITRIDING AND NITROCARBURISING

Nitriding treatment is commonly recommended to enhance surface properties of RAVNEX HD.

Nitriding treatment for hot-work applications is performed by producing diffusion zone only ( nitriding phase)
of a depth determined by particular application requirements, and completely inhibit surface compound layer
( and nitriding phases).

Nitriding treatment for plastic-molding or cold-work applications with wear resistance requirements is performed by
producing surface compound layer of composition and thickness determined by articular application requirements.

For applications with requirement for additional surface protection, improvement of sliding properties, or improvement
of corrosion resistance, it is recommended that oxidation treatment (Fe3O4) follows the nitriding.

For details on surface preparation and setup of nitriding treatment parameters to obtain required surface properties
please consult our approved nitriding specialist.

800

700
Temperature (°C)

600

500

400

300
0 0.1 1 10
Nitriding potential

Nitriding of hot-work applications (limited or no compound layer)

Nitriding of cold-work applications (well developed compound layer)
Nitriding for intermediate surface properties

Lehrer diagram presented in figure shows the effect of two parameters:

(1) nitriding potential (a function of partial pressure of ammonia and hydrogen), and (2) temperature, on composition of
nitriding phases formed on material surface. Figure shows recommended selection of the two governing parameters for
appropriate execution of nitriding for two extreme application regimes, hot ork on one hand, and cold-work on the other.

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T h e n a m e y o u c a n t r u s t • M E T A L R A V N E

WELDING AND EDM

WELDING

RAVNEX HD is a readily weldable alloy by TIG or MMA welding processes in hardened or soft-annealed condition.
Filler metal should be of the same or similar chemical composition.

Heat treatment after welding is recommended. Annealing should be performed after welding of soft annealed parts, whereas
tempering at temperature of about 50 °C below tempering temperature should be performed after welding of hardened
and tempered parts. Laser welding is recommended for repair of smaller cracks and edges.

PREHEATING TEMPERATURE MAXIMUM INTERPASS TEMPERATURE POST WELD COOLING

320 °C 470 °C Approximately 30 °C / h to not

less than 70 °C, then tempering.

WELDING METHOD FILLER MATERIAL HARDNESS AFTER WELDING

TIG, MMA H11, exceptional H13 ~ 50 HRC

ELECTRICAL DISCHARGE MACHINING

Electrical discharge machining (EDM) leaves a brittle surface layer due to melting and resolidification of surface material.

It is recommended to: (1) remove the resolidified layer by polishing, grinding or other mechanical methods,
and (2) temper the work-piece at temperature of about 50 °C below the tempering temperature.
Execution of tempering of re-hardened and jet untempered layer underneath the surface is critical.

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M E T A L R A V N E • T h e n a m e y o u c a n t r u s t

RECOMENDATIONS FOR MACHINING

The information below is provided solely as a general machining guideline. It refers to material in soft annealed condition.

DRILLING

INSER DRILL DIAMETER (mm) CUTTING SPEED (m/min) FEED (mm/rev)

K15 - K20 5 - 20 70 0.05 - 0.15

FACE MILLING

INSERT CUTTING SPEED (m/min) FEED (mm/tooth) DEPTH OF CUT (mm)

P30-P40 c.* (rough milling) 60 - 100 0.20 -2.00

P10-P20 c.* (fine milling) 75 - 130 0.20 -2.00

TURNING

INSERT CUTTING SPEED (m/min) FEED (mm/rev) DEPTH OF CUT (mm)

P30-P40 c.* (rough turning) 65 - 100 -1.00 -4.00

P10 c.* (fine turning) 140 - 200 -0.30 -2.00

* c. = coated carbide

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T h e n a m e y o u c a n t r u s t • M E T A L R A V N E

CASE STUDY

HEAT TREATMENT OF RAVNEX HD

Control of quenching is critical to assure dimension stability, optimum microstructure and mechanical properties of any
work-piece.

Finite element modelling of heat treatment reveals that both hardening temperature and soaking time, as well as quenching
rate strongly depend on work piece size and geometry.

> FIG 1

Figure 1 shows temperature distribution in

two workpieces of different thickness at a
given time (t), (see Figure 2) during quenching.
One can observe a hot core and a high
temperature gradient in a thick workpiece,
while a thin workpiece has at same cooling
time almost uniform temperature distribution.

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M E T A L R A V N E • T h e n a m e y o u c a n t r u s t

> FIG 2
1100

900

800

700
Temperature (°C)

600

500

400

300

200

100

0
0 10 20 t 30 40 50 60
Time (min)
ISOQ
A1 A2 B1 B2 C1

Figure 2 reveals temperature transient at quenching for both workpieces at two characteristic
points: (1) a point 15mm underneath the surface, and (2) the core.

> FIG 3
800

700

600

500
T (°C)

400

300

200

100

0
0 10 20 30 40 50 60
Time (min)

A2 - A1 B2 - B1 B2 - C1

Figure 3 shows temperature difference between the two characteristic points for both workpieces for the same
quenching transient. An extreme temperature gradient occurs in the thick workpiece, with high risk of causing
distortion or gross cracking. Application of isothermal quenching process (see NADCA#207) is recommended
to reduce the potential detrimental effects of extreme temperature difference. A short isothermal hold reduces
significantly the temperature gradient in the thick workpiece.
(See surface temperature transifnt curve C1ISOQ in Figure 2 and Figure 3.)
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T h e n a m e y o u c a n t r u s t • M E T A L R A V N E

To achieve optimum material properties, heat treatment parameters should be adjusted to specific workpiece size and
geometry. Critical quench rate is needed to avoid both pearlite formation and carbide precipitation.

In order to run quenching of a particular dimension and geometry workpiece at optimum velocity it is critical to continuously
monitor temperature of both the surface and the core throughout the cycle.

> FIG 4
300

250

200
Cooling velocity (°C/min)

150

100

50

0
20 30 40 50 60 70 80 90 100 110 120
V/A (mm)

CORE SURFACE CORNER

Figure 4 shows average cooling speed between 800 and 500°C at the core of a generalized geometry workpiece. Both geometry and size of the
workpiece is defined by its volume (V) to surface (S) ratio. Medium quenching power in a vacuum-type furnace is applied to determine the workpiece
cooling speed (6 bar N2 overpressure with medium to high gas circulation). The plot is particularly useful for determining optimum quenching
speed in workpieces where temperature at core is not possible to directly monitor by thermocouple.
SURFACE - temperature at a point 15 mm underneath the center of largest workpiece surface.
CORNER* - temperature at a point 15 mm underneath the most exposed part of workpiece.

* data presented are computed for a point 15mm underneath an angle of a cube.

SHARP EDGES ON THE TOOL IN HEAT TREATMENT SHOULD BE AVOIDED TO PREVENT GROSS CRACKING
TIP 4 OR MICRO QUENCHING CRACKS WHICH CAN LEAD TO FORMATION OF LEADING CRACKS.

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M E T A L R A V N E • T h e n a m e y o u c a n t r u s t

Notes

16
 RAVNEX HD is produced by:

METAL RAVNE, d.o.o.

Koroπka cesta 14, 2390 Ravne na Koroπkem, Slovenia
Telephone: +386 2 870 7000, Telefax: +386 2 870 7006
E-mail: info@metalravne.com
www.metalravne.com

RAVNEX HD is distributed by:

Publisher: Ravne Steel Center • Text: Metal Ravne • Production: RD BORGIS • AD/D: XLMS • Photos: archive Metal Ravne • Print: ALE d.o.o. • June 2014