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HITACHI
FORGED HIGH SPEED
STEEL ROLLS
May 2013
Hitachi Power Solutions Co., Ltd.
CX-12-029R2
2000Ton Forging Press & 40MT Manipulator
© Hitachi Power Solutions Co., Ltd. 2013 All right reserved.
●Hitachi Forged HSS rolls
Hitachi has developed HSS rolls for sendzimir-mill from the 1950s, and has supplied many
small HSS rolls to the sendzimir-mill customers. After that, from the 1980s, proprietary was
carried out and the ESR equipment "rotational ESR bimetallic method " which has a special
structure was succeeded in development by compounding the HSS roll for tandem-mill, with
difficult manufacture by solid body.
According to the expansion of hybrid car, etc., Hitachi has supplied HSS rolls (Hitachi
symbol, E61) and Super HSS rolls (Hitachi symbol, E70) to the hard materials rolling
tandem-mill, such as silicon steel, now.
● Hitachi Forged Semi-HSS rolls
Hitachi has introduced Advanced ESR equipment, featured (1) fully coaxial high current
feeding system, (2) swing control system, in 2008. This ESR method can supply a quality
ESR ingot with fine dendrite micro structure. By application of this ESR method, the grinding
control for Semi-HSS roll is greatly improved Advanced ESR is applied to manufacturing
the rolls for the rolling mill of high-strength steel sheet and hard tin plate, and Hitachi
supplies Semi-HSS roll (Hitachi symbol, FH-20) of the solid body which reconciled wear
resistance and grinding control.
Year
Material Transition and Manufacturing Development
ESR(20ton) Ladle Refining
Low Frequency Induction Hardening
Sub Zero Treatment
Automatic Ultrasonic Detection
ESR(10ton)
Rotational ESR
Bimetallic Method
Ultrasonic Hardness
Penetration Measurement
High Speed Steel
FH-15 (5%Cr)
FH-11 (3%Cr)
FH-8 (2%Cr)
CNC Lath Machine
Power-up
CNC Carving Machine
Wear Resistance
’75 ’80 ’85 ’90 ’70 ’95 ’00 ’05 ‘10
Advanced
ESR(20ton) 6000ton Forging Press
2000ton Forging Press
Wear Resistance
and
Grinding Control
Development of Hitachi Forged HSS Rolls
1
© Hitachi Power Solutions Co., Ltd. 2013 All right reserved.
Finished Rolls
Spheroidizing
Automatic Ultrasonic Flaw Detection
Thermal Refining
EF-Melting + LF-LD
Forging
Spheroidizing
Machining
Automatic Ultrasonic
Flaw Detection
Core
Rotational ESR
Bimetallic Method
Pipe-Shaped
Electrode
Rough Machining
Finish Machining
Heat Treatment
Final Inspection
Packing
Manufacturing Process of HSS Rolls
Forging
2
© Hitachi Power Solutions Co., Ltd. 2013 All right reserved.
Rotational ESR Bimetallic Method
Down
Up
Pipe-Shaped
Electrode
Core
Water-Cooled
Rotational Crucible
Molten Slag
Molten Pool
Rotational Plate Carbon Brush
Characteristics
Wide range combination of shell and core
High purity and Fine and Sound structure
High strength boundary layer between shell
and core
High performance High-Speed-Steel Roll
Core Pipe-Shaped
Electrode
Synchronously Rotation
Hitachi HSS Rolls
Outer Layer
Set up Melting Set off
A Cross- sectional
Macrostructure of
Composite Ingot
3
© Hitachi Power Solutions Co., Ltd. 2013 All right reserved.
400μm
Advanced ESR Method
Characteristics
Feeding System ; Fully Coaxial High Current Feeding System
Control System ; Slag Pool Resistance Swing Control
High quality ESR Ingot with ultra fine dendrite structure
Hitachi Semi-HSS Rolls
Ram Drive system
XY Adjustment
Load cell System
Sliding Contact
Exhaust & Atmospheric Protection Hood
Gantry
Slag Feeder
Coaxial Bus bar
Stationary Mold Crucible
Base Plate
Ingot
Molten Slag
Forged Electrode
Stub
Power Supply
400μm Conventional ESR Advanced ESR
Dendrite arm space by advanced ESR is a half of conventional ESR. (Compared to our company’s products)
20mm depth from roll surface
20mm depth from roll surface
4
Electrode Ram
Molten Pool
© Hitachi Power Solutions Co., Ltd. 2013 All right reserved.
CB60M100VGP
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
Ro
ug
hn
ess (
Ra)
E61 E70
GC320GmB
5SG60/80(H12VSK-1)
CX60/80(E+/F+/E+12V101P)
5SG46(H12VSG1P)
CX46(E+/F+/E+12V101P)
CB80M125VN1E
CB60M100VN1E
CB325P60Bw4
Hitachi Symbol
Recommendation of Grinding Wheel
Specification for HSS Rolls
5
© Hitachi Power Solutions Co., Ltd. 2013 All right reserved.
HITACHI FORGED ROLL MATERIALS
Actual performance
0
0.5
1.0
1.5
5%Cr FH-20
Wear Resistance
We
ar
Am
ou
nt
(mm
dia
.)
Roll
Symbol
Wear profile of strip edge contacted
portion
FH-15
(5%Cr)
FH-20
FH-20 Semi-High Speed Steel Roll
Test piece
Φ40×8
Mild steel
Φ40×8
Slip ratio: 30%
5%Coolant
Test Method
Wear amount:
1/6 Strip edge Strip
0 Strip edge Strip
Actual rolling performance
6
© Hitachi Power Solutions Co., Ltd. 2013 All right reserved.
HITACHI FORGED ROLL MATERIALS
Hi-NC roll has primary carbide in the matrix, it makes the wear resistance
much higher than usual rolls.
Especially E61 and E70 are high speed steel type material which can be
tempered over 500 ℃.
Table 1 shows the characteristics of Hi-NC roll.
Table1. Characteristics of Hi-NC roll
・Wear amount after 500ton hard material rolling ----------- Fig.1
・Example of surface roughness drop ----------- Fig.2
0
10
5
5%Cr
Forged roll
Hi-NC
(E61)
Wear
am
ou
nt (m
m d
ia.)
200
0
40
Su
rfa
ce
rou
gh
ne
ss d
rop
ratio
(%
)
400 600 800 0 80
Rolled tonnage (ton)
Hi-NC roll
(E61)
5%Cr (Forged roll)
Fig.1 Wear amount after 500ton hard material rolling Fig.2 Example of surface roughness drop
Characteristics of High Speed Steel Roll
Actual performance
Material Classification Primary carbide Characteristics Rolling
FH-20 Special Material M7C3
Wear resistance
(Dull keeping)
Mild
steel
E61 High speed steel MC, M2C, M6C Wear resistance
Abrasion resistance
Hard
material
E70 Super High
speed steel MC, M2C, M6C
Wear resistance
Abrasion resistance
Hard
material
E61,E70 (Hi-NC) High Speed Steel Roll
7
© Hitachi Power Solutions Co., Ltd. 2013 All right reserved.