DURO for Hot WorkSpecial Steels for Precise Die and Mold
RFor Hot WorkHigh Toughness Grade

DURO-N1High Strength Grade

DURO-F1

DURO-Created by NACHI’s original technology
Steels with high toughness and strength forprecise die and mold
• DURO series, special steels for precise die and mold, are high quality and high grade materials
which are made by NACHI’s original technology of steel manufacturing and refining.
• They have less non-metallic inclusion and segregation that may cause fractures, and shows
superior performance because of the best control for carbide quantity and size.

Properties of DURO for Hot Work
Good•DURO for Hot Work has two
type grades, High Toughness
Grade is DURO-N1, HighStrength Grade is DURO-F1.
•Each grade has a different
balance of toughness andwear resistance, so whatever
the applications, there is a
DURO grade available.

: DURO

H13Toughness

DURO-N1
H10

Hot Work Tool Steels

DURO-F1

H19

Matrix HSS

Strength in high temperature

Good

Typical Nachi Steel Grades
Classification

High Speed Steels(HSS)

Conventional HSS

SKH9D

Die and Punch
Plus Punch

HM42
FAX SeriesPunch

ICS22

Die for Eye Glasses

MDS9Mold for Rubber

MCR1

Die and Punch

DURO-F1, 3, 7, SP

Cold Work Die and Punch

DURO-F1, N1

Hot Work Die and Punch

Plastic Mold Steel with Corrosion
Resistance and Mirror Finish

PROVA-400

Plastic Mold

Corrosion and Wear Resistance
Alloy Steel

NPR1

Injection Molding Machine Parts

Die and Mold Steel for Cold Work

Steel for Precise Die and Mold
(DURO Series)
FM ALLOY

Application

HSU2C

Powder Metallugical HSS

Alloy Tool Steels

Grade1

FM ALLOY is

DURO isa brand name for NACHI’s newest materialproducts. Made from NACHI’s own technology tobe high performance alloys with finemicrostructure control.

named from the Latin word which means “hard”
or “endure”. A description for our tough materials
to be used for die and mold.

Benefits of DURO
• DURO is made by a highly purified procedure, to have high toughness and fatigue strength
because of very little non-metallic inclusions.
• Quantity and size of carbides in DURO microstructure are controlled to have a superior balanceof toughness and wear resistance.
Classification

GradeHardness

DURO-N1

HRC 50-54

Strong Points

High Toughness
Hot Working
Die and MoldSteelHigh Strength
Matrix HSS

Super high toughness die and mold steel
Has excellent high toughness with strength in hightemperature.

High toughness die and mold steel

DURO-F1

HRC 54-60

Shows superior high hardness and toughness comparedwith usual hot work tool steels.

*DURO-F1 is also good for cold work, please reference NACHI catalog “DURO for Cold Work.”

Microstructure
DURO-N1

H13

DURO-F1

DURO series havethe best balance forquantity and size ofcarbides in each
grade, and a uniform
microstructure withminor segregation.

*Nital etching × 5002Features of DURO Series for Hot Work
Mechanical Properties

Superior impact resistance in high temperature
250

Charpy Impact Resistance (J/cm2)

Sample: JIS No.3
200150100
DURO-N1H1350
DURO-F100200

400600800

Test Temperature (˚C)

DURO-N1 shows higher
impact resistance than H13 intemperature R.T. to 600 ˚C(Warm working zone).

Excellent tensile strength in high temperature

3000
Sample: JIS No.4

Tensile Strength (MPa)2500

DURO-F1

2000

DURO-N11500

H131000500
00200

400600

Test Temperature (˚C)

3800

DURO-N1 and F1 have highertensile strength than H13 intemperature R.T. to 700 ˚C.

Superior wear resistance
OGOSHI’s test
Rotor: SCM435
Distance: 200 m
Final load: 6.3 kg
No lubricant

8Wear Ratio ×10-4(mm3/kgf・m)

76H1354

DURO-N1

3Good

2

DURO-F1

1000.511.5

22.5

Friction Speed (m/s)

Hardersituation

3

DURO-N1, F1 show higher
wear resistance than H13.

Great heat check resistance

1.00

250.80

Number of heat check

Length of heat check (mm)per 1 mm × 1 mm sq.

0.60

0.40

0.20

0.00

20151050
DURO-F1

DURO-N1

H10H13

DURO-F1

DURO-N1, F1 have high strength in hightemperature and show great heat checkresistance.

DURO-N1

H10H13Heat check test• Heating 700 ˚C A Water cooling 4sec A Air cooling 2sec
(1292 ˚F) @@• Cycle: 1000

4

Features of DURO Series for Hot WorkHeat treatment of DURO for Hot WorkHeat treatment condition
GradeRequirement

Aus. [˚C (˚F)]

Temp. [˚C (˚F)]

Hardness (HRC)

For toughness

1030 (1886)

620 × 2 (1148)

50.5Standard

1050 (1922)

600 × 2 (1112)

52.0

For strength in hightemperature

1070 (1958)

580 × 2 (1076)

53.5

For toughness

1080 (1976)

600 × 2 (1112)

54.5

Standard1100 (2012)

580 × 2 (1076)

56.0

For strength in hightemperature

1140 (2084)

580 × 2 (1076)

57.5

DURO-N1

DURO-F1*Thickness of sample: 50 mm, vacuum furnace + pressure gas quenching (about 4 bar)
*Hardness may vary depending on material size and method, condition or facilities of heat treatment.

Heating time
GradeHolding time

DURO-N1
DURO-F1

Diameter or thickness of work (mm)
< 15255075100150200

Aus. (min)1525

4050607080

Temp. (hr)11.52

3456Aus. (min)1.546791218

Temp. (hr)1123456*Heating time of DURO-N1 should be decided same as normal hot work tool steels, and DURO-F1 as Matrix HSS.

■Applications
GradeApplication

Life comparison

Die for hub forming

1.7 times longer than H10

Die for forging

2 times longer than H19

Forging punch

2.2 times longer than H13

Knock out punch

2.2 times longer than H13

Forging punch

4 times longer than H10Ring punch for forging

2.4 times longer than H10

DURO-N1

DURO-F15Quenched and tempered hardness chart
DURO-N1

55

Hardness (HRC)

54
53
Aus. Temp. (˚C)

521080
1070
1050

511030

DURO-N1 can be used in range HRC 50-54.
For special applications it can also beused at HRC55 or HRC48.

1020

50
49
540

560

580

600

620

640

Tempering Temp. (˚C)

DURO-F1

61

Hardness (HRC)

60
59
58

Aus.Temp. (˚C)

5711601140

561120
1100

55

1080

54500

520

540

560

580

600

DURO-F1 can be used in range HRC 54-60.
To get HRC60 it is suggested to use asalt bath furnace.

620

Tempering Temp (˚C)

■Sample choices of steel grade for applications
Current Grade

H13 type

H10 type

H19 type

Matrix HSS

M2

Recommendation

Life Factor
DURO-N1

DURO-F1

Heat deformation, Heat check◎○Fracture○

Heat deformation, Heat check○Fracture○◎◎

Heat deformation, Heat check◎Fracture○

Heat deformation, Heat check
Fracture◎○○◎

Heat deformation, Heat check
Fracture◎ : Best ○ : Good6

S4302E
2008.01.X-ABE-ABE