NOPR Collection:

Experimental investigation of the effects of friction stir processing and shot peening on mechanical properties of ductile iron

Sat, 01 Jun 2019 00:00:00 GMT

Title: Experimental investigation of the effects of friction stir processing and shot peening on mechanical properties of ductile iron Authors: Obaid, Abdul Salam Y Abstract: Friction stir processing (FSP) and shot peening (SP) have been developed as surface hardening techniques and have been studied by several researchers to produce an upper surface modification of metallic materials for enhancing improved mechanical properties of different materials. In this study, the influences of these method son mechanical properties of ductile iron ASTM A536, grade (80-55-06) ferrite/pear lite have been investigated. The micro hardness, strength and fatigue life of the ductile iron have been analyzed. Microscopic investigations reveal graphite grain refinement and crashing of 100% of the original size with FSP and 50% with SP on the processed surfaces. The hardness increases by 200% and 100% compared to as cast for FSP and SP applications, respectively. The elongation, ultimate tensile strength and fatigue life have been increased by 28%, 22% and 233% using FSP respectively whereas, the increments are 18%, 8% and 66% using SP compared with the original ductile iron. The stated improvements have been related to surface modification, residual stresses and phase transformations through the employed processes in this study. Page(s): 181-185

Comparison of performance of different tool electrodes during electrical discharge machining

Sat, 01 Jun 2019 00:00:00 GMT

Title: Comparison of performance of different tool electrodes during electrical discharge machining Authors: Sahu, Anshuman Kumar; Mahapatra, Siba Sankar Abstract: In this work, performance of tool electrode prepared through selective laser sintering (SLS) process has been studied along with traditional copper and brass electrodes for electrical discharge machining (EDM) of AISI 1040 stainless steel. Performance measures like material removal rate (MRR), tool wear rate (TWR), radial over cut (ROC) and average surface roughness (R_a) of the machined surface have been considered. Multi-response optimization like technique for order preference through similarity to ideal solution (TOPSIS) method has been used to find out the best parametric setting of the EDM process for maximization of MRR and minimization of TWR, ROC and R_a. Scanning electron microscopic (SEM) images of the machined surface reveals that less surface crack density (SCD) has been formed on the machined surface by the use of AlSiMg RP tool electrode followed by brass and copper tool electrodes. Although MRR decreases with the use of AlSiMg tool electrode, good surface finish with less surface crack density on the machined surfaces has been observed as compared to other two tool electrodes. SEM and EDX analysis of the machined surfaces by different tool electrodes reveals presence of tool materials on the machined surfaces with increased carbon content. Therefore, it has been recommended that AlSiMg tool electrode can be conveniently adopted for finishing and semi-finishing operations. Page(s): 186-199

Form tolerances investigation in EDM process for super alloys using multiple holes electrodes

Sat, 01 Jun 2019 00:00:00 GMT

Title: Form tolerances investigation in EDM process for super alloys using multiple holes electrodes Authors: Dhanabalan, S; Sivakumar, K; Narayanan, C Sathiya Abstract: The present work focuses on experimental quality analysis of electrical discharge machining (EDM) of two super alloys namely Inconel 718 and Inconel 625 with different diameter of hole of multiple holes copper electrodes. The diameter of hole of multiple holes in electrode, pulse current and (Ton) pulse on time have been chosen as process parameters to conduct the experiment trails. The MRR, EWR and form tolerance have been considered as output responses. Page(s): 200-204

Study on surface characteristics of friction stir processed AZ91 with titanium carbide micro particles

Sat, 01 Jun 2019 00:00:00 GMT

Title: Study on surface characteristics of friction stir processed AZ91 with titanium carbide micro particles Authors: Vijayan, S; Gnanavel, J P Lalith; Selvakumar, G; Rao, S R K Abstract: Magnesium alloys are gaining importance as structural materials in automotive and aerospace industries. Surface properties such as wear and corrosion resistance have to be improved in order to enhance the usability and application of these materials. Fabrication of magnesium based metal matrix composites is one of the possible ways to improve the surface properties. Friction stir processing (FSP) is a solid-state surface processing technique which enhances the surface properties such as hardness, strength, resistance to corrosion and wear without affecting the bulk properties of the material. In this paper, magnesium alloy AZ 91 has been friction stir processed using titanium carbide particles to form a surface composite. The FSP process parameters used in these investigations are transverse speed of 0.5 mm/sec; rotational speed of 1000 rpm and the axial load of 8 kN. The friction stir processed specimens have been subjected to pin on disc wear test to study the effects of micro particle reinforcement on the surface. The specific wear rate and co efficient of friction have been computed. The fabricated surface composites of AZ 91 with TiC particle exhibited better wear resistance and enhancement in micro hardness compared to the base metal properties. The maximum hardness of 146 VHN has been measured on FSP surface composites against the base metal hardness of 70 VHN. Metallurgical characterization has been done using optical microscopy, EDAX and scanning electron microscopy images. Page(s): 205-210