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The world's leading producer of heat treatment equipment
Best Nitriding Technology: ZeroFlow®
October 18, 2016
The world's leading producer of heat treatment equipment
Faces for Radio
2
Director - Thermal ProductsMark Hemsathe: [email protected]: 419-356-3500
Director – Aftermarket & MarketingDoug Glenne: [email protected]: 724-923-8089
The world's leading producer of heat treatment equipment
Overview
3
/ Who is SECO/WARWICK?
/ Technology and R & D Capabilities
/ Gas Nitriding – ZeroFlow® Technology/ What is Nitriding/ Gas Savings with ZeroFlow/ Success Stories/ - FNC Truck Gears/ - Nitriding Extrusion Dies
The world's leading producer of heat treatment equipment
Poll Question #1
4
/ What type of Nitriding do you currently do?
The world's leading producer of heat treatment equipment 5
vacuum furnaces
thermal furnaces
melting furnaces CAB aluminum
process
SECO/WARWICK - Broad Range of Thermal Processing Solutions
The world's leading producer of heat treatment equipment 6
Ukiah, CA Meadville, PA
Europe
IndiaChina
Global Presence
The world's leading producer of heat treatment equipment
Technology and Research & Development
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R&D
8
/ Industrial-sized Furnaces and Metallographic Laboratory
/ Demonstrate equipment performance and technology with customer parts
/ Cooperation with Industry & Universities
/ Domestic & International R&D Projects
/ Technology Development/ Single Piece Flow LPC/HPGQ/ Gas Heated Vacuum/ Plasma Activation in Gas Nitriding
The world's leading producer of heat treatment equipment
R&D - Furnaces
9
The world's leading producer of heat treatment equipment
Plasma Activation Gas Nitrider
The world's leading producer of heat treatment equipment
ZeroFlow® Gas Nitriding
The world's leading producer of heat treatment equipment
Pusher Walking Beam/Hearth Car Bottom Box
Rotary Retort Rotary Hearth Bell Tip-Up
Roller Hearth Mesh Belt Batch Retort Pit
Continuous Production Batch Production
Most Common Equipment Types
12
The world's leading producer of heat treatment equipment
ZeroFlow® Nitriding - Retort
13
/ Sealed Retort Based Process
/ Available in Vertical or Horizontal Configuration
/ Available in Electric or Gas Heated Option
/ Available in Multiple Sizes, up to 13,000 lbs Gross Load
/ Capable of Multiple Processes/ Gas Nitriding/ Ferritic Nitrocarburizing/ Post-Oxidation
/ Fulfill AMS2750D, AMS2759/10/12
/ ZeroFlow Process reduces consumption of NH3
Verti
cal F
urna
ces
Horiz
onta
l Fur
nace
s
The world's leading producer of heat treatment equipment
What is gas nitriding?
Gas nitriding is a process which consists of saturating the steel parts surface with available nitrogen (free nitrogen atoms), while the parts are at nitriding temperature. The process is time and atmosphere dependent:
2NH3 3H2 + 2N
Fe
in order to achieve:
• high surface hardness• good fatigue resistance• galling, adhesion and cavitation wear resistance• improved corrosion resistance in iron.
SECO/WARWICK©
The world's leading producer of heat treatment equipment
What is FNC?
Similar to Gas Nitriding, but free Carbon is added to assist with adding both carbon to the surface and Nitrogen in the metal :
Carbon can be added in the form of CO, CO2 or other gases.
2CO [C] + CO2
• FNC is a faster way to add surface hardness to low carbon steels• Improved corrosion resistance in iron, especially after high
temperature oxidation over compound layer.
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The structure of nitrided layer
e – Fe2-3N zone
g’ – Fe4N zone
a – FeN zone
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Two-stage nitriding (Floe process) with use of NH3+ dissNH3 mix (or N2, H2)
NH3
NH3
dissNH3
dissociator
NH3+dissNH3
furnace
A
valves
gas flowmeters
gas analyzer
The world's leading producer of heat treatment equipment
Gas Consumption
18
The world's leading producer of heat treatment equipment
The growth kinetics of nitrided layer is controlled by 2 parameters: T & Np
The nitrided layer – e+g’+a or g’+a or a (grinding is not required)
Time process
Nitr
idin
g pa
ram
eter
sControl gas nitriding with use of NH3 – ZeroFlow process
TT
QNH3
KN
QNH3
I stage: NH3
II stage: NH3
KN
The world's leading producer of heat treatment equipment
Gas Consumption
20
/ In largest installation of ZeroFlow to date, Reduction of Ammonia 8:1
/ Replaced Pusher style furnace with 5 large Retort units
/ Ammonia use went from 160 Metric Tons to 20 Metric Tons!
The world's leading producer of heat treatment equipment
Process Benefits:
• ZeroFlow is Gas Nitriding.
• ZeroFlow nitriding: Lower consumption of process gas.
• ZeroFlow nitriding: Easy control of growth Kinetics of the nitrided
layer.
Recap of ZeroFlow® Solution for Gas Nitriding
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Equipment Design:
• Vacuum Purge: Lower consumption of Nitrogen gas.
• Turbo Cooler: Shorter Cycle leads to more productive unit
• Convection: Very critical in Uniform gas nitriding
• Electric or Natural Gas: Designs to heat with either.
Recap of ZeroFlow® Solution for Gas Nitriding
The world's leading producer of heat treatment equipment
Comparison of NH3 consumption and N2 +H2O
emission during nitriding of crankshaft in ZeroFlow® and
Floe process
0
5
10
15
20
25
30
35
40
45
50
consumption emission
NH 3
cos
nsum
tion
and
N 2 + H
2O e
mis
sion
, m3
ZeroFlow
Floe
ZeroFlow
Floe
4340St. I: 490oC, 2h, rN=25atm-1/2
St. II: 530oC, 15h, rN =0.6atm-1/2
St. III: 530oC, 12h, rN =0.4atm-1/2
The world's leading producer of heat treatment equipment
NH3 and N2 consumption as well as gas emission H2O & N2 during nitriding of crankshaft using current processes
0
10
20
30
40
50
Gas
con
sum
ptio
n an
d em
issi
on, m3
NH3 and N2 consumption H2O+N2 emission
NH3ZeroFlow
NH31-stage
NH3+NH3zdys.2-stages
NH3+N2
NH3ZeroFlow
NH31-stage
NH3+NH3zdys.2-stages
NH3+N2
40 NiCrMo 6I st.: 490oC, 2h, KN = 15II st.: 530oC, 15h, KN = 0,6III st.: 530oC, 13h, KN = 0,4
N2
NH3
NH3
NH3
NH3
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Hardness distribution
0
100
200
300
400
500
600
700
800
0 0,1 0,2 0,3 0,4 0,5 0,6
Distance from the surface, [mm]
Har
dnes
s, H
V 0
,1
4340I st.: 490oC, 2h, Np =2 5
II st.; 530oC, 15 h, Np =0,6III st.: 530oC, 12 h, Np =0,4
gefHV400 = 0,4mm
gefHV600 = 0,15mm
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Compound layer on 4340
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Ferritic nitrocarburizing of teeth on truck engine gears – 8:1 Reduction NH3
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Nitrocarburizing Requirements
• Compound zone: 10-15 µm• Effective Case Depth (DNC): minimum 0,30 mm
(core hardness + 50HV criterion)• Porosity < 40%
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Root of tooth Flank of tooth
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Ferritic nitrocarburizing of teeth on truck engine gears
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Poll Question #2
31
/ Do you have trouble with Compound (White) Layer control?
The world's leading producer of heat treatment equipment
Ferritic nitrocarburizing of teeth on truck engine gears
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Ferritic nitrocarburizing of teeth on truck engine gears
The world's leading producer of heat treatment equipment
Aluminum extrusion dies tests:ZeroFlow® nitriding layer control tests layer phase
structure, thickness, and hardness were performed on samples from H13 in the form of slices cut from dies.
die divided into slices
dimensions of a part represented dies for extruding
hollow profiles dimensions of a part represented
dies for extruding flat profiles
track
gap
The world's leading producer of heat treatment equipment
Distribution of hardness in slices of dies nitrided with the ZeroFlow® method for different
parameters of stage II of the process; (stage I parameters: T=490°C, KN=15 atm-½, t=1 h)
Varying the Kn & Time, and Resultant Layer Profile
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a) “hollow” b) “hollow”
c) „gap” d) „gap”
Structure of the calibrating belt of a cutting of a die nitrided with: Stage I KN=15 atm-½; t=1 h, T=490°C, Stage II KN=0.4 atm-½; t=55 h,
T=550°C,a-b) on the side of the hollow, c-d) on the side of the gap
The world's leading producer of heat treatment equipment 37
Aluminum Processed before Die Failure
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a) “hollow” b) “hollow”
c) „gap” d)„gap”
Structure of the calibrating belt of a cutting of a die nitrided with: Stage I KN=15 atm-½; t=1 h, T=490°C, Stage II KN=1.0 atm-½; t=55 h, T=550°C,a-b) on the side of the
hollow, c-d) on the side of the gap
The world's leading producer of heat treatment equipment
0
2
4
6
8
2 4 6 8 10
Time [h]
Thic
knes
s of
e+
g ' zon
e [m m
]
0
1
2
3
4
Nitr
idin
g po
tent
ial K
N
KN
e+g'
4140530oC
II stage
I stage20 l NH3/min
KN
The kinetics of growth and reduction of the e+g zone in a two-stage process – sample of the 4140 steel:1st stage: 100%NH3,2nd stage: NH3 inflow entirely closed (variant 1) or atmosphere changed to NH3+NH3diss. (variant 2)
variant 2with a flow of NH3+NH3diss.
zero flow of NH3
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Absorption isotherm of nitrogen in the e-Fe2Ny phase, determined experimentally in atmospheres obtained from NH3, NH3+H2 and NH3+NH3diss.
8
8,4
8,8
9,2
9,6
10
0 4 8 12 16 20
Nitriding potential KN
Nitr
ogen
con
tent
[%N
]
e-Fe2N1-y phase500oC
equilibrium was determined in:NH3+H2 mix flowing through a quarz retort NH3+NH3diss. mix circulating in steel retort (without its flow through the retort)
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Equipment Designs for Gas Nitriding
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Equipment Designs for Gas Nitriding
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HRN horizontal nitriding furnace
Exhaust hatchHeating
elements
Cooling air blower
Cr-Ni retort
Atmosphere mixer
Light insulation
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VRN vertical nitriding furnace