Presentation on Stellite hardfacing repair

PROJECT ON

STELLITE HARDFACING REPAIR

ByGaurav Kale.

Sponsored Industry: KOSO INDIA, Pvt. Ltd, Nashik.

K.K. Wagh Institute of Engg. Education & Research, Nashik

Hardfacing is a metalworking process where harder or tougher material is applied to a base metal.

WHAT IS HARDFACING?

Before Hardfacing: After Hardfacing:

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%)

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:

Flaws overcome strategies:

Modify the present Welding Process Specification(WPS).

Suggest the new procedure according to the metallurgical properties of work piece if any.

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.

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:

Specimen creation :

We are working on:

Alloy steel material: A182.

Specimen creation:Diameter : 100mmThickness:40mm

OUR OBSERVATIONS:

Stellite reacts differently with alloy steels.

Alloy steel is softer compared to cast steel

Hardfacing on alloy steel job with conventional method:

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

Hardfacing on alloy steel specimen using

BUFFER LAYER:

Preheating the specimen:

Preheating of specimen:

Buffering process observations:

Welding process GMAW welding

Buffer Material SS 316L.

Preheat temperature 100-150℃

Interpass temperature 150℃

Current 182 A

Buffer Material:•Stainless Steel.

•Manganese Steel.

•Nickel based steel.

•Copper based steel.

Stainless steel electrode:

BUFFERING ANALYSIS:

Specimen Testing:

Hardfacing on buffered specimen:

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

Shield Gas 15LPM

Observations for Hardfacing on buffered specimen:

CONCLUSION

Sr. No. Parameter Conventional method

Modified method

1Rotation speed

meter

0.42 RPM 0.42 RPM

2Powder speed 11.6 gm/min 11.6 gm/min

3Voltmeter 19.6 V 29 V

4Ammeter 120 A 130 A

5Powder gas 3.7 LPM 4.3 LPM

6Centre Gas 2.6 LPM 5LPM

7Shield Gas 6 LPM 15LPM

Comparison Between Conversional welding and Hardfacing

after Buffering process: