The document discusses hardfacing, a metalworking process that improves the durability of base metals by applying tougher materials, specifically focusing on stellite variants. It identifies flaws such as cracks and porosity in current hardfacing methods, proposing a buffering process that uses intermediate hardness material before applying the hardfacing layer. Experimental results show different reactions and parameters for conventional and modified hardfacing techniques, indicating performance improvements with the new buffering method.

1. By
Gaurav Kale.
Sponsored Industry: KOSO INDIA, Pvt. Ltd,
Nashik.
K.K. Wagh Institute of Engg. Education & Research, Nashik

2. Hardfacing is a metalworking process
where harder or tougher material is applied
to a base metal.
WHAT IS HARDFACING?
Before Hardfacing:
After Hardfacing:

3. Hardfacing Materials:
1. Stellite:
• Grade 6
• Grade 12
Sr.No. Elements (%) Grade 6 Grade 12
1 Carbon 0.9-1.4 1.2-1.7
2 Silicon 2 1
3 Manganese 1 2
4 Phosphorous 0.016 0.016
5 Sulphur 0.015 0.015
6 Chromium 26-32 26-32
7 Nickel 3 3
8 Molybdenum 1 1
9 Iron 3 3
10 Tungsten 3-6 7-9.5
11 Cobalt Remaining (min
60%)
Remaining (min
60%)

4. FLAWS DURING HARDFACING:
Currently the industry is facing some problems in this
(Hardfacing) processes such as,
1. Cracks.
2. Porosity
3. Blowholes..
Cracks in the specimen:

5. Flaws overcome strategies:
 Modify the present Welding Process
Specification(WPS).
 Suggest the new procedure according to the
metallurgical properties of work piece if any.

6. Our Research and study:
 Removing flaws not possible just by modifying the
present WPS.
 We found a process in which the base metal is welded
first with intermediate hardness material.
• The process is known as Buffering Process.

7.  In buffering process, the material of intermediate
hardness between alloy steel and stellite is hardfaced
first on valve part and then hardfacing of stellite is
done.
 Here, we are using stainless steel for buffering.
Buffering Process:

8. Specimen creation:
Diameter : 100mm
Thickness:40mm

9. OUR OBSERVATIONS:
Stellite reacts differently with alloy steels.
Alloy steel is softer compared to cast steel

10. Hardfacing on alloy steel job with conventional
method:

11. Observations for hardfacing
(With convensional method):
Parameter Observations
Rotation speed meter 0.42 RPM
Powder speed 11.6 gm/min
Voltmeter 19.6 V
Ammeter 120 A
Powder gas 3.7 LPM
Center gas 2.6 LPM
Shield gas 6 LPM

13. Buffering process observations:
Welding process GMAW welding
Buffer Material SS 316L.
Preheat temperature 100-150℃
Interpass temperature 150℃
Current 182 A

14. •Stainless Steel.
•Manganese Steel.
•Nickel based steel.
•Copper based steel.
Stainless steel electrode:

15. BUFFERING ANALYSIS:
Specimen Testing:

16. Hardfacing on buffered specimen:

17. Parameter Reading
Rotation speed meter 0.42 RPM
Powder speed 11.6 gm/min
Voltmeter reading 29 V
Ammeter reading 130A
Powder gas 4.3 LPM
Centre Gas 5LPM
Observations for Hardfacing on buffered specimen:

18. CONCLUSION

19. Sr. No. Parameter Conventional
method
Modified
method
1
Rotation speed meter 0.42 RPM 0.42 RPM
2
Powder speed 11.6 gm/min 11.6 gm/min
3
Voltmeter 19.6 V 29 V
4
Ammeter 120 A 130 A
5
Powder gas 3.7 LPM 4.3 LPM
6
Centre Gas 2.6 LPM 5LPM
Comparison Between
Conversional welding and Hardfacing after Buffering
process: