Thermo-Chemical Processing in LPG / CO2

Atmospheres for Energy and

Cost Savings

Pratap Ghorpade (Hightemp Furnaces Limited)

and

Keith Bennett (KMB Metallurgical)

Page – 1

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

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

Carb

on

pote

nti

al -

CP

Slide - 2

Load Charge Temperature Recovery Boost TimeDiffuse

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

38

5

9

6

42

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)

Hardn

ess (H

V)

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 ACM process)

Slide - 5

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

Hard

ness (

HV

)

1. FC-35-ACM930 Deg C. x 6 hour – 830 Deg.c. x 0 min 130 Deg.C. Mar quenchOxygen Probe : 1160 mVEndogas930 Deg.C. x 6 hour – 850 Deg.C. x 0 min 130 Deg.C. Mar QuenchOxygen Probe : 1160 mV

2. Analysis methodAnalysis 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

Slide - 8 Photograph of processed components

40 mm

30 mm

20 mm

10 mm

0 mm

60

Dia 5

Dia 20 mm

Blind Hole Test PieceSlide - 9

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)

EC

D (m

m)

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

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)

EC

D (m

m)

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)

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

Ø 5

.96

Ø 9

.5

Ø 1

7

26.425.3

Slide – 11

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

400

500

600

700

800

Distance from surface (mm)

Hardn

ess (H

V)

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

1415

12

8

5

6

7

10

Case Depth Uniformity test for the Injector ValveSlide – 13

14 POSITION SPECIMEN DATA

Carbo-Nitriding

In FC35

Atmosphere

Slide-14

2CO = C + CO2

2NH3 = 2N + 3H2

Slide- 15

MICRO STRUCTURE OF A PART CARBONITRIDED IN FC-35 ATMOSPHERE:

Magnification: 400X

Slide -16

Hardness Profiles of Nine Test Samples

Carbonitrided in FC - 35

0.05 0.15 0.2 0.25

Distance from Surface ( mm )

Hard

ness

( H

V )

0

100

200

300

400

500

600

700

800

SAMPLE3

SAMPLE9

SAMPLE8

SAMPLE7

SAMPLE6

SAMPLE5

SAMPLE4

SAMPLE2

SAMPLE1

Slide -17

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

Ca

se

De

pth

( m

m )

Slide-18

COST SAVINGS

Slide 19

Comparative Costs in India – 2005

Nitrogen/Methanol Rs355/hr

Endogas Rs369/hr

FC20 Rs239.4/hr

FC35 Rs231/hr

Slide -20

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

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

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

Case D

epth

indiv

idual s

am

ple

s

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

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

150º C

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

Ha

rdn

es

s v

alu

e in

HV

Meatllurgical Examination Results:

Traverse in

mm1 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 HRCTwo Wheeler Starter Shaft

Slide-24

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

Hard

ness

(BHN)

LSL

USL

Slide-25