1. Thermo-Chemical Processing in LPG / CO2
Atmospheres for Energy and
Cost Savings
Pratap Ghorpade (Hightemp Furnaces Limited)
and
Keith Bennett (KMB Metallurgical)
Page – 1

2. The FC35 process
The FC 35 process is applicable to the
Sealed Quench Furnace.
Pusher Furnace
Chamber
Vestibule &
Quench
Tank
Exit
Conveyor
Charge
Slide - 1 Schematic of Hightemp Sealed Quench Furnace

3. Boosting Diffusion
HCP
LCP
Conventional Method
(with Nitrogen – Methanol or
Endothermic gas)
LCP
HCP
DiffusionBoosting
FC 35 - ACM Method
(with LPG – CO2)
FC-35-ACM Method
Time
Carbonpotential-CP
Slide - 2

4. Load Charge Temperature Recovery Boost Time
Diffuse
time
Hardening
Time
Oil
Quench
930 Deg.C 930 Deg.C
850 Deg.C
ACM
HCP = 1.10%
LCP = 0.90%
LCP=0.90%
LCP=
0.70%
Constant
CO2-1 (lpm)
Controlled
CmHn-3 (lpm)
(3) Post wash and Temper
Slide - 3 Typical Process Cycle
A typical process cycle would be as follows
(1) Prewash(2) Carburise and Harden in a Sealed Quench Furnace

5. 38
5
9
6
4
2
7
1
Samples Location
450
500
550
600
650
700
750
800
0.1 0.3 0.5 0.7 0.9 1.1
Distance from surface (mm)
Hardness(HV)
No.1 No.2 No.3 No.4 No.5 No.6 No.7 No.8 No.9
0.2 0.4 0.6 0.8 1.0
Front
Back
Nine sample Hardness Traverse on Rocker Arm (FC-35 ACMSlide - 5

6. 450
500
550
600
650
700
750
800
0.1 0.3 0.5 0.7 0.9 1.1
Distance from surface (mm)
No.2 FC 35 No.5 Endo
0.2 0.4 0.6 0.8 1.0
Slide -6 Hardness Traverse Comparison on Rocker Arm (FC 35 AM Vs Endogas
Hardness(HV)

7. 1. FC-35-ACM
930 Deg C. x 6 hour – 830 Deg.c. x 0 min
130 Deg.C. Mar quench
Oxygen Probe : 1160 mV
Endogas
930 Deg.C. x 6 hour – 850 Deg.C. x 0 min
130 Deg.C. Mar Quench
Oxygen Probe : 1160 mV
2. Analysis method
Analysis of the carbon content was made by an emission spectro analysis
1.1
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
0.5 1.0 1.5 2.0
Distance from the surface (mm)
Carbon Gradient Comparison (FC35 vs. Endogas )Slide - 7

8. Slide - 8 Photograph of processed components

9. 40 mm
30 mm
20 mm
10 mm
0 mm
60
Dia 5
Dia 20 mm
Blind Hole Test PieceSlide - 9

10. 0.5
0.55
0.6
0.65
0.7
0.75
0.8
0.85
0.9
0.95
1
5 mm 10 mm 20 mm 30 mm 40 mm
Distance from surface of hole (mm)
ECD(mm)
Specimen 1 Specimen 2 Specimen 3
Distance 5 mm 10 mm 20 mm 30 mm 40 mm
ECD-1 0.85 0.82 0.75 0.66 0.63
ECD-2 0.90 0.85 0.69 0.65 0.60
ECD-3 0.95 0.75 0.70 0.70 0.65
Blind Hole Test ECD Data (FC35}Slide - 10

11. 0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
5 mm 10 mm 20 mm 30 mm 40 mm
Distance from surface of hole (mm)
ECD(mm)
FC 35 ACM Endogas
Distance 5 mm 10 mm 20 mm 30 mm 40 mm
ECD-Endo 0.80 0.70 0.50 0.30 0.20
ECD-FC35 0.95 0.75 0.70 0.70 0.65
Blind Hole Test ECD Data (FC35} Vs EndoSlide – 10 (a)

12. B
A
C
0.5 + 0.3 mm
0.6 + 0.3 mm
0.45 + 0.2 mm
HRC 57-63
ECD (mm) HV513Location
Material SCM 420
Diesel Injector Valve (Body Nozzle)
C
B
A
Ø5.96
Ø9.5
Ø17
26.425.3
Slide – 11

13. Sample Surface
Hardnes
s
Core
Hardness
ECD
(mm)
ECD
(mm)
ECD
(mm)
Location HRC HV A B C
1 58.7 369 0.74 0.59 0.58
2 59.7 386 0.71 0.57 0.56
3 59.8 375 0.65 0.56 0.59
4 60.1 361 0.67 0.56 0.59
5 58.6 383 0.73 0.59 0.68
6 58.4 373 0.71 0.64 0.59
7 58.4 399 0.70 0.59 0.53
8 58.9 406 0.69 0.60 0.60
9 58.8 340 0.61 0.51 0.55
10 58.7 350 0.62 0.54 0.58
11 59.4 374 0.68 0.58 0.62
12 59.3 363 0.68 0.54 0.70
13 60.1 420 0.77 0.61 0.64
14 59.2 398 0.67 0.56 0.60
15 61.2 401 0.76 0.63 0.66
Average 59.29 379.9 0.693 0.578 0.605
Carburising
Hardening
Tempering
900 Deg.C
830 Deg.C
170 Deg.C
3 hours
45 min
2 hours
Cool
Cold Oil Quench
50 Deg C
Air Cool
Injector Valve Test DataSlide - 12

14. 400
500
600
700
800
Distance from surface (mm)
Hardness(HV)
A 750 720 718 650 630 550 470
B 730 670 640 550 550 490 480
C 690 640 620 570 550 500 470
0.1 0.2 0.3 0.4 0.5 0.6 0.7
1
3
4
1
29
11
13
14
15
12
8
5
6
7
10
Case Depth Uniformity test for the Injector ValveSlide – 13
14 POSITION SPECIMEN DATA

15. Carbo-Nitriding
In FC35
Atmosphere
Slide-14

16. 2CO = C + CO2
2NH3 = 2N + 3H2
Slide- 15

17. MICRO STRUCTURE OF A PART CARBONITRIDED IN FC-35 ATMOSPHERE:
Magnification: 400X
Slide -16

18. Hardness Profiles of Nine Test Samples
Carbonitrided in FC - 35
0.05 0.15 0.2 0.25
Distance from Surface ( mm )
Hardness(HV)
0
100
200
300
400
500
600
700
800
SAMPLE3
SAMPLE9
SAMPLE8
SAMPLE7
SAMPLE6
SAMPLE5
SAMPLE4
SAMPLE2
SAMPLE1
Slide -17

19. Case Depth Uniformity in FC - 35 Carbonitriding Process
0
0.05
0.1
0.15
0.2
0.25
1 2 3 4 5 6 7 8 9
Sample Test Pieces No
CaseDepth(mm)
Slide-18

20. COST SAVINGS
Slide 19

21. Comparative Costs in India – 2005
Nitrogen/Methanol Rs355/hr
Endogas Rs369/hr
FC20 Rs239.4/hr
FC35 Rs231/hr
Slide -20

22. Comparative Costs in UK In 2005
Nitrogen/Methanol £5.34/hr
Endogas £5.75/hr
FC20 £3.82/hr
FC35 £3.28/hr
Slide-21

23. CONCLUSIONS
• The FC 35 process has the ability to carburise components of difficult
geometry.
• Costs associated with the provision of furnace atmosphere are such that
extensive savings are available in comparison with the costs of classical
processes.
• Savings are available from a reduction in process cycles.
• Further cost and energy savings are available by eliminating the
requirement for endothermic generators. This also results in saving floor
space
• The reduction in gases exhausted (waste exhaust gas is 1/50 than that from
endothermic gas method) into the atmosphere makes the process
environmentally acceptable.Slide – 22 Conclusions

24. Component Name Plunger
Process Name Carbonitriding
Raw material EN1A
Metallurgical Specifications
Surface Hardness 450 HV Min
Case Depth 0.30 ~ 0.50 mm
Example of a Carbo Nitrided Part
Hardening Cycle Tempering Cycle
890º C 160º C
815°C
Time (mins) 120 20Mins Quench Oil Temperature 50 deg.cel.Time 60 minutes
CP % 1.15 0.95 Quench Time 30 minutes
CO2 (lpm) 1 (Constant) 0 Agitator 300 rpm
Ammonia 17 cfh
LPG (lpm)Variable through motorised valve
(maximum flow 3.0 lpm)
Case Depth Distribution Graph
0
0.1
0.2
0.3
0.4
0.5
0.6
1 2 3 4 5 6 7 8 9
Samples 1 to 9
CaseDepthindividualsamples
Case Depth (mm) Surface Hardness(HV)
0.50 762
0.45 772
0.45 762
0.50 752
0.45 762
0.50 772
0.45 762
0.45 752
0.50 772
Min. to Max. 0.45~0.50 mm 752 ~ 772 HV
8
9
4
5
6
7
Sample No
1
2
3
Plunger (Brake part)
Slide-23

25. Example of a Carburised Part
Hardening Cycle
920° C 920° C
850°C
Time (mins) 90 30 20 Quench Oil Temperature 50 deg.cel.
CP % 1.10~0.90 0.85 0.85 0.85 Quench Time 45 minutes
CO2 (lpm) 1.0 constant 0 0 Agitator 400 rpm
LPG (lpm) Variable through motorised valve
(maximum flow 3.0 lpm)
Tempering Cycle
150ºC
Time 90 minutes
Case Depth Distribution Chart
0
100
200
300
400
500
600
700
800
0.10 0.30 0.50 0.60 0.70
Traverse in mm
HardnessvalueinHV
Meatllurgical Examination Results:
Traverse in
mm
1 2 3 4 5 6 7 8 9
0.10 728 741 740 737 734 758 740 735 750
0.30 684 691 709 673 693 691 696 656 705
0.50 594 589 592 611 588 590 590 600 615
0.60 565 560 545 543 550 560 565 570 585
0.70 490 527 495 495 503 521 498 520 520
ECD(mm) 0.65 0.66 0.59 0.59 0.60 0.64 0.65 0.65 0.66
Core (HRC) 36 38 38 37 39 38 38 38 38
Surface(HRA) 81 82 82 82 83 83 82 82 83
Hardness Traverse of 9 Samples as per above locations
Process Carburising
Raw Material SCM 420H
Metallurgical Specifications
Surface hardness 80-84 HRA
Case Depth 0.40-0.70 mm(HV550)
Core hardness 32-41 HRC
Two Wheeler Starter
Shaft
Slide-24

26. Example of a Through Hardened Part
Process Through Hardening
Raw Material AISI 4140H
Metallurgical Specifications
Surface Hardness 311-353 BHN
Rocker Lever
Hardness Uniformity
200
240
280
320
360
400
1
2
3
4
5
6
7
8
9
Sample Number
Hardness(BHN)
LSL
USL
Slide-25