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DC53
The evolution of tool steel
A) GENERAL CHARACTERISTICS
DC53 is a new general-purpose cold work die and mold steel whose strength and toughness approach those of high-speed steels.
DC53, is an improvement over alloy tool steel D-2 specified in Standard (JIS) G4404. It eliminates the disadvantages of insufficient hardness and toughness, resulting from high-temperature tempering found with D-2, and is intended to replace D-2 in use for general purpose and precision dies.
B) UNIQUE CHARACTERISTICS
- Higher hardness (62-64 HRc) than D2 after heat treatment.
- Twice the toughness of D2 with superior wear resistance.
- Substantially higher fatigue strength compared to D2.
- Smaller primary carbides than D2 protect the die from chipping and cracking.
- Secondary refining process (DLF) reduces impurities.
- Machines and grinds up to 40% faster than D2.
- Less residual stress after wire EDMing.
Fatigue Strength
Temper Resistance
APPLICATIONS
- Stepped punch and press-punching dies
- Concrete sprayer parts, rotor plates
- Swaging dies and backers
- Dies for cold forging
- Thread-rolling circular dies
- Piercing punch
- Thread-rolling dies for heat-treated bolts
- Forming dies
- Stripper plates for lead frame blanking
- Gauges
- Screws for injection molding machines
- Plastic Molds
BENEFITS
Welding
Lower minimum pre- and post-heating temperature than D2 reduces the incidence of weld
cracking and simplifies welding. Low hardness decline in heat affected zone minimizes
deterioration in die performance.
Weld Rod
any appropriate weld rod used for high carbon, high chrome die steels such as D-2.
Machining/Grinding
Machines and grinds better and faster than D2 for longer tool life and reduced tool manufacturing time.
EDM
Residual stress caused by quenching is minimal in DC53. Therefore, problems such as cracking
and distortion are prevented during and after wire electro-discharge machining.
Sub-surface hardness decline of DC53 just below wire electro-discharge machining is much
less than D2; thus making DC53 dies more durable.
Stability
High-temperature tempering (520°C) allows maintenance of die accuracy without the
troublesome application of subzero treatment, reducing costs and increasing productivity.
Surface Enhancements
Surface hardening treatments such as CVD, PVD, TD, and nitriding require the use of high
temperatures. DC53’s higher inner hardness than D2 after such treatments, preventing the
hardened layer from peeling off and making surface hardening treatments more effective.
Wear
Superior wear-resistance coupled with high toughness make DC53 suitable for use in
wear-resistant parts subject to impact and bending stress.
Strength
Dies made of DC53 and heat-treated using standard method possesses up to 25% higher
bending strength than D2. Secondary refining decreases nonmetallic inclusions and carbide
size for a substantially increased fatigue strength that of D2.
Toughness
Superior impact value minimizes fracture and chipping problems thus ensuring
more durable dies.
Toughness (Charpy)
PHYSICAL PROPERTIES
Coefficient of Thermal Expansion (x10-6/C°)
|
-100° C |
-200° C |
-300° C |
-400° C |
-500° C |
-600° C |
-700° C |
| DC53 |
12.2 |
12.0 |
12.3 |
12.8 |
13.2 |
13.4 |
13.0 |
| Annealed |
Coefficient of Thermal Conductivity (cal/cm·sec°C)
|
Room Temp. |
-100° C |
-200° C |
-300° C |
-400° C |
-500° C |
-600° C |
| DC53 |
0.057 |
0.060 |
0.064 |
0.064 |
0.065 |
0.062 |
|
| Quenched and Tempered |
| Specific Gravity (g/cm3) |
7.87 |
| Young's modulus (E) |
21,700 |
| Modulus of Rigidity (G) |
8,480 |
| Poisson's Ratio (v) |
0.28 |
GENERAL DESIGN GUIDELINES\
Strength
DC53 high hardness (HRc62) coupled with standard methods of heat treating result in
superior bending strength, up to 25% higher than D2. Ideal for dies to form high tensile
steel plates and other heavy-thickness steel plates and cold forming tools undergoing
high loads such as dies for bending and cold forging.
A secondary refining process minimizes the size of carbides and decreases nonmetallic
inclusions for a substantially increased fatigue strength over D2. This characteristic makes DC53
suitable for use where repeated stresses are loaded, such as precision-punching dies with
small clearance and cold forming tools. DC53 is particularly suited to handling
less-workable materials such as stainless and heat-treated alloy steels.
Stability
Dimensional changes of dies in operation are caused mainly by decomposition of retained
austenite. High-temperature tempering (520° to 530°C) reduces the presence of austenite
to 5% or less, providing the same effect as the troublesome application of subzero treatment.
This reduction in retained austenite makes DC53 particularly suitable for precision dies and
gauges where dimensional changes during operation must be minimized
Note: As with any cold work die steel, when dealing with close tolerance parts and tempering
at the high tempering temperature, it is necessary to temper a third time @ 400°C. This helps
to minimize the occurrence of grain growth and distortion that may occur weeks or even months
after heat treat.
Hardness
DC53 can be hardened to 62-64 HRc in the same manner as D2, and when tempered at high
temperatures (520° to 530°C), it assumes excellent properties. Even when tempered at lower
temperatures (180° to 200°C), its performance is equivalent to or better than that of D2. This
improved hardenability makes heat treatment easier and reduces hardness problems due to
vacuum heat treatment, which uses gas cooling.
 
Smaller primary carbides give DC53 twice the toughness of D2
WEAR PROPERTIES
DC53 displays superior wear-resistance to D2 when tempered at high temperatures (520°C)
and equal wear resistance to D2 when tempered at low temperatures. High resistance to
temper softening minimizes seizing and galling on the die surface. DC53 is ideal for dies
needing to maintain high surface hardness against frictional heat between the die surface
and the worked materials.
PROCESSING GUIDELINES
Hardness decline due to grinding heat is also prevented, thus raising die performance.
EDM
In order to perform highly accurate wire electro-discharge machining, it is recommended
that high-temperature tempering (520°C or higher) be conducted twice to minimize heat
treatment residual stress. Reduction of residual stress is insufficient if applying subzero
treatment and repeated tempering at low temperatures. In order to avoid deceleration of
machining speed, rust formation, and galvanic corrosion, the following procedures are
recommended.
- Make the machining fluid spray pressure as high as possible and place the upper and
lower nozzles close to the material to be worked in order to smoothly wash away the
sludge formed on the machined surface. This is especially necessary for machining
heavy-walled materials.
- Maintain specific resistance of machining fluid at an appropriate value. If the specific
resistance falls (electric conductivity of machining fluid rises), galvanic corrosion and
deterioration of the layer tend to occur due to the influence of electrolization.
- In addition to the above, consider use of a rust-preventive agent to prevent rust and
adoption of the immersion process (which prevents the machined surface from coming
into contact with the air and oxidizing).
Heat Treating
Standard heat treatment conditions are shown in the diagrams and tables below. As shown in
the CCT curve graph, DC53 is superior in hardness to D2 and can be quenched sufficiently by air
or gas cooling in a vacuum furnace. DC53 and D2 require the same austenitizing temperatures
(1,020 – 1,040°C) and can be heat-treated at the same time. High temperature tempering
(520°C or higher) allows DC53 to retain its high hardness and wire electro-discharge
machinability. Even when tempered at low temperatures (180-200°C), DC53 remains twice as
tough and equal or higher in hardness (wear resistance) than D2.
Demensional changes due to heat treatment.
Recommendations on Heat Treatment
Heating procedure in quenching and tempering is basically identical for both DC53 and D2.
However, the conditions outlined below are recommended according to use and purpose.
Heat Treatment Temperature According to Use and Purpose
Use, Purpose |
Heat Treatment Temperature (°C) |
Hardness used
(HRc) |
Quenching |
Tempering |
Dies where galling and seizing resistance are important:
1. High tensile steel sheet forming die
2. Deep drawing, die
3. Cold forming die
Cold forging punch, die Thread-rolling die
4. Thick plate bending die
|
1,030 to 1,040; |
520 to 530 (x2) |
62-63 |
Tools and Jigs required to have high toughness:
1. Metal blade to handle comparatively thick (>1mm) plate
Shear blade, slitter
2. Slender punch
|
1,010 to 1,020
1,020 to 1,030 |
530 to 540 (x2)
200 to 300 (x2) |
57-60
58-61 |
Cases where secular dimensional change is important (elimination of subzero treatment)
1. Precision die, gauge
|
1,020 to 1,030 |
520 to 530 (x2) & 400 (x1) |
61-63 |
Note: Double high-temperature tempering is absolutely necessary. The best combination of mechanical properties of DC53 are obtained with double tempering between 520oC (968oF) and 510oC (1050oF). The range between 450oC (842oF) and 510oC (950oF) are to be avoided due to the occurrence of the formation of fresh martinsite that will cause premature chipping and cracking.
Note: As with any cold work die steel, when dealing with close tolerance parts and tempering at
the high tempering temperature, it is necessary to temper a third time @ 400°C. This helps to
minimize the occurrence of grain growth and distortion that may occur weeks or even months
after heat treat.
Dimensional Changes due to Heat Treatment of a Shaped Block
DIE APPLICATIONS
Blanking dies for electric home appliance components
| Working |
Material Worked |
Conventional die steel |
DC53 |
&Approx. dimensions (mm) |
| Cold pressing |
Ni-based alloy (0.2 mmt) |
D2
HRc58/59
Tempered at 510°C |
HRc62/63
Tempered at 520°C |
35tx100Wx250L |
| Evaluation |
5,000S |
25,000S |
5 times |
Considerations
 |
Conventional Steel–The worked material is tough and chipping
and seizing of the die edge were problematic.
DC53–Both high temperature tempering and high hardness
are important in preventing seizing and extending the life of the
die edges. High hardness, when tempered at high temperature,
and homogeneous structure of DC53 were greatly effective in
meeting these requirements. |
FB punches for electric appliance components
Application
FB punches for hook-shaped electric appliance components. Long, thin shape promotes
severe conditions.
Results
| Working |
Material Worked |
Conventional die steel |
DC53 |
&Approx. dimensions (mm) |
| Fine blanking |
1045 (HRB80 1.5 mmt) |
D2
HRc56
Tempered at 510°C |
HRc62/63
Tempered at 530°C |
70ø x 110L |
| Evaluation |
1,600S |
3,900S |
2.4 times |
Considerations
 |
Conventional Steel–Cracking and fracturing at the tip of the long, thin
shape, shortened life.
DC53–Because of DC53’s excellent toughness, hardness could be
increased, resulting in more than double the life. |
Plastic molds for electric appliance components
Application
Injection molds for electromagnetic switch boxes. Since the material worked is FRP resin, wear
in the area surrounding the gate is particularly problematic.
Results
| Working |
Material Worked |
Conventional die steel |
DC53 |
&Approx. dimensions (mm) |
| Injection Molding |
ABS-FRP resin (25% filler) |
D2
HRc59
Tempered at 510°C |
HRc63
Tempered at 520°C |
90tx150Wx250L |
| Evaluation |
4,800S |
26,000S |
5.8 times |
Considerations
 |
Conventional Steel–The mold was discarded due to wear occurring
in areas surrounding the gate and where the flow of resin became
irregular.
DC53–Applying the highest hardness of DC53 (HRc63) proved highly
effective in combating simple wear. |
Cold forging punches for electric instrument components
Application
Working of bushings by backward extrusion.
Results
| Working |
Material Worked |
Conventional die steel |
DC53 |
&Approx. dimensions (mm) |
| Cold Forming |
1020 (8mmø) |
D2
HRc59
Tempered at 510°C |
HRc62/63
Tempered at 520°C |
17ø x 80L |
| Evaluation |
20,000S |
65,000S |
3.2 times |
Considerations
 |
Conventional Steel–Wear of punch edge and galling lateral face shortened
durability.
DC53–To prevent wear and galling, hardness of DC53 was tempered at a high
level, resulting in expected extension of life (due to its high toughness, this
material resists cracking.) |
Flat thread rolling dies
Application
Flat thread rolling dies for working stainless steel bolts where there is a particularly high working
load.
Results
| Working |
Material Worked |
Conventional die steel |
DC53 |
&Approx. dimensions (mm) |
| Thread Rolling |
SS304 (5mmø) |
D2
HRc60
Tempered at 500°C |
HRc62/63
Tempered at 530°C |
40tx80Wx190L |
| Evaluation |
3,800S |
21,000S |
5.5 times |
Considerations
 |
Conventional Steel–Chipping and local seizing of threads, required
early regrinding.
DC53–In working with stainless steels, high toughness, high
hardness, and high resistance to temper softening are necessary.
DC53 proved effective. |
Rolls for straightening machines
Application
Straightening of heat-resistant steel and stainless steel where pitting of the roll is a major
problem and high hardness and toughness are required.
Results
| Working |
Material Worked |
Conventional die steel |
DC53 |
&Approx. dimensions (mm) |
| Straightening |
SS400 Series(8-10mmø) |
D2
HRc58
Tempered at 510°C |
HRc61/62
Tempered at 520°C |
200øx280L |
| Evaluation |
12Ton |
50Ton |
4 times |
Considerations
| |
Conventional Steel–Pitting of roll surface and local seizing occurred,
terminating life.
DC53–The basic characteristics of DC53 fully met the requirements
for high toughness to prevent pitting and high hardness to prevent
seizing. |
Trimming dies for bolt (hexagonal)
Application
This type of die is commonly used. Surface hardness treatment is applied depending on the
material worked and the precision of the finish required.
Results
| Working |
Material Worked |
Conventional die steel |
DC53 |
&Approx. dimensions (mm) |
| Trimming |
5140 (HRc23 16mmØ) |
Semi-high speed steel
HRc60
CVD-treated |
HRc62/63
Tempered at 520°C
CVD-treated |
48øx35L |
| Evaluation |
11,000S |
42,000S |
3.5 times |
Considerations
 |
Conventional Steel–Chipping of the cutting-edge and insufficient
base hardness of the die led to termination of life.
DC53–To increase the effectiveness of surface treatment, higher
base hardness of the die should be considered. High hardness of
DC53 proved effective. |
Shear blades for steel sheet
Application
Shear blades to slit all types of steel sheet, particularly high-tensile steel sheet or thick plate
where chipping of the blade edge is problematic.
Results
| Working |
Material Worked |
Conventional die steel |
DC53 |
&Approx. dimensions (mm) |
| Shearing |
High-tensile steel sheet (1.3mmt) |
D2
HRc61
Tempered at 200 °C |
HRc62
Tempered at 530°C
|
30tx180W x2,100L |
| Evaluation |
11 days |
27 days |
2.5 times |
Considerations
 |
Conventional Steel–Chipping of the cutting-edge and insufficient
base hardness of the die led to termination of life.
DC53–To increase the effectiveness of surface treatment, higher
base hardness of the die should be considered. High hardness of
DC53 proved effective. |
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