**Author details**

*Recent Advancements in the Metallurgical Engineering and Electrodeposition*

Based on the above studies, the following conclusions can be drawn.

and austenite grain size and structures become homogeneous.

1.Both Trial 4 (without Ce) and Trial 7 (with Ce) weld metals are responds in austempering heat treatment at 300 and 350°C for 1.5, 2 and 2.5 h holding time. At 300°C microstructure shows needle shape bainitic ferrite with retained austenite however at 350°C shows feathery shaped bainitic ferrite with retained austenite. Ce content in weld metal to refine the bainitic ferrite

2.Volume percentage of retained austenite and its carbon content changed with changing the austempering temperature and holding time. At 300°C shows less amount of retained austenite with higher amount of bainitic ferrite. However at 350°C shows higher amount of retained austenite with comparatively less amount of bainitic ferrite. Retained austenite also varied with varying the austempering holding time at respective temperature and shows maximum retained austenite content at 2 h holding time at each austempering temperature for both the weld metals. However, Ce content in weld metal to enlarge the process windows to delay the stage I reaction and shows more amount of retained austenite at each austempering

3.The microhardness of weld metal shows lower value at 350°C, presence of higher amount of retained austenite than 300°C austempering temperature. With changing the austempering holding time, the hardness values are changed and show lower hardness value at 2 h holding time with respective austempering temperature. Ce content in weld metal decreased the hardness value and shows at both the temperature, presence of higher amount retained austenite and homogeneous microstructure. Tensile test result shows failure take place from the base metal for both Trial 4 and Trial 7 weld metals at 300 and 350°C for 2 h holding time to indicate the 100%

4.Charpy impact values are changes with changing the austempering temperature with changing the amount of retained austenite in weld metal. 350°C shows higher impact value for both weld metals presence of higher amount of retained austenite. Ce in weld metal to improve the Charpy impact value as a result of refine the microstructure and increasing the amount of retained austenite. Maximum Charpy impact value shows at Trial 7 weld metal at 350°C

5.Fatigue strength of both welded joints was improved with improving the austempering temperature. At 350°C feathery shaped bainitic ferrite with higher amount of retained austenite illustrate higher fatigue strength than needle shaped bainitic ferrite with small amount of retained austenite at 300°C. Presence of Ce content in weld metal Trial 7 weld metal shows higher fatigue strength at both austempering temperature due to lower hardness and

6.Fatigue fracture surface shows at 300°C temperature predominantly mixture with dimple and reverse pattern quasi-cleavage types fracture, however at 350°C shows dimple types fracture to indicates ductile in nature. Ce content

**4. Conclusion**

temperature.

joint efficiency.

austempering conditions.

higher Charpy impact value.

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Tapan Sarkar Metallurgical and Material Engineering Department, Welding Technology Centre, Jadavpur University, Kolkata, India

\*Address all correspondence to: tapansarkar.met@gmail.com

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