Nipun Mittal | Clemson University (original) (raw)
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Papers by Nipun Mittal
SAE Technical Paper Series, 2020
International Journal of ChemTech Research
In the present scenario, Powder metallurgy (P/M) manufacturing process is one of the fastest grow... more In the present scenario, Powder metallurgy (P/M) manufacturing process is one of the fastest growing fields which involves the processing of metal powders for the production of steels and has replaced all traditional methods of metal forming operations because of its low relative material wastage, low capital cost and maximum material utilization. Producing steels through the P/M route has immense potential for industrial applications in making components for machine parts, in the fields of automobiles such as fasteners, bearings, rollers, in manufacturing field such as tools, cutters, and also in the field of aerospace, defense etc. The microstructures and mechanical properties mainly depend on the final obtained density of sintered P/M alloy steels which will determine the component characteristics. The present study has been made to investigate the cutting tool wear behaviour of sintered/hot extruded P/M alloy steels with Fe-1% C as base material, W (Tungsten) and Ti (Titanium) as alloying elements. The cutting tool wear behavior was analyzed with the help of tool bits grounded from the head portion of extruded preforms with standard tool parameters for machining the non-ferrous materials by varying the cutting speed, whereas the feed and depth of cut was kept constant, and also the dry sliding wear behavior were studied on pin-on-disc (ASTM G99) arrangement. By using the optical microscopy (OM), the microstructure of extruded P/M alloy steels has been characterized to understand the structure-property relationships. The presence of WTi Carbide in both the extruded P/M alloy steels significantly enhances the tool wear resistance. Widmanstatten type ferrite-cementite matrix (alternate lamellas) microstructure is revealed on both the extruded P/M alloy steels.
Engineering Failure Analysis, 2019
Boiler tubes used as water walls made up of ferritic steels is having some finite life, because o... more Boiler tubes used as water walls made up of ferritic steels is having some finite life, because of prolonged exposure in the furnace at elevated temperature, stress and aggressive environment, tube failure taking place. Now a day's premature failure of the boiler tube mainly in water walls is one of the very common phenomena in the thermal power plants. The present investigation was done on the as-received ASTM SA 210C failed boiler tube steel used as water walls in the Circulating Fluidized Bed Combustion (CFBC) coal fired thermal power plant. An attempt has been made to understand the cause, because identifying correct failure mechanism often helps to perform meaningful life assessment and also to prevent the future Boiler Tube Failure (BTF). The as-received of failed tube along with the parent (unused) tube from the water wall raiser panel were selected to study for mechanical and metallurgical properties. Tensile test and micro hardness examinations were carried out on both the parent tube and failed tube. Visual examination reveals "fish-mouth" appearance of the as-received failed tube because of short-term overheating. The micro structure of the parent metal has the conventional structure of ferrite (white constituent) and pearlite (dark constituent), whereas for the as-received failed tube reveals Widmanstatten ferrite. A detailed structure-property relationship has been made by using the combined techniques of Optical Microscopy (OM), SEM/EDAX and XRD. Tensile fractography depicts the presence of micro-voids coalescence in the fibrous network shows ductile mode failure in the as-received failed boiler tubes.
SAE Technical Paper Series, 2020
International Journal of ChemTech Research
In the present scenario, Powder metallurgy (P/M) manufacturing process is one of the fastest grow... more In the present scenario, Powder metallurgy (P/M) manufacturing process is one of the fastest growing fields which involves the processing of metal powders for the production of steels and has replaced all traditional methods of metal forming operations because of its low relative material wastage, low capital cost and maximum material utilization. Producing steels through the P/M route has immense potential for industrial applications in making components for machine parts, in the fields of automobiles such as fasteners, bearings, rollers, in manufacturing field such as tools, cutters, and also in the field of aerospace, defense etc. The microstructures and mechanical properties mainly depend on the final obtained density of sintered P/M alloy steels which will determine the component characteristics. The present study has been made to investigate the cutting tool wear behaviour of sintered/hot extruded P/M alloy steels with Fe-1% C as base material, W (Tungsten) and Ti (Titanium) as alloying elements. The cutting tool wear behavior was analyzed with the help of tool bits grounded from the head portion of extruded preforms with standard tool parameters for machining the non-ferrous materials by varying the cutting speed, whereas the feed and depth of cut was kept constant, and also the dry sliding wear behavior were studied on pin-on-disc (ASTM G99) arrangement. By using the optical microscopy (OM), the microstructure of extruded P/M alloy steels has been characterized to understand the structure-property relationships. The presence of WTi Carbide in both the extruded P/M alloy steels significantly enhances the tool wear resistance. Widmanstatten type ferrite-cementite matrix (alternate lamellas) microstructure is revealed on both the extruded P/M alloy steels.
Engineering Failure Analysis, 2019
Boiler tubes used as water walls made up of ferritic steels is having some finite life, because o... more Boiler tubes used as water walls made up of ferritic steels is having some finite life, because of prolonged exposure in the furnace at elevated temperature, stress and aggressive environment, tube failure taking place. Now a day's premature failure of the boiler tube mainly in water walls is one of the very common phenomena in the thermal power plants. The present investigation was done on the as-received ASTM SA 210C failed boiler tube steel used as water walls in the Circulating Fluidized Bed Combustion (CFBC) coal fired thermal power plant. An attempt has been made to understand the cause, because identifying correct failure mechanism often helps to perform meaningful life assessment and also to prevent the future Boiler Tube Failure (BTF). The as-received of failed tube along with the parent (unused) tube from the water wall raiser panel were selected to study for mechanical and metallurgical properties. Tensile test and micro hardness examinations were carried out on both the parent tube and failed tube. Visual examination reveals "fish-mouth" appearance of the as-received failed tube because of short-term overheating. The micro structure of the parent metal has the conventional structure of ferrite (white constituent) and pearlite (dark constituent), whereas for the as-received failed tube reveals Widmanstatten ferrite. A detailed structure-property relationship has been made by using the combined techniques of Optical Microscopy (OM), SEM/EDAX and XRD. Tensile fractography depicts the presence of micro-voids coalescence in the fibrous network shows ductile mode failure in the as-received failed boiler tubes.