VOL. 11, NO. 20, OCTOBER 2016 ISSN 1819-6608 ARPN Journal of Engineering and Applied Sciences © 2006-2016 Asian Research Publishing Network (ARPN). All rights reserved. www.arpnjournals.com 11960 LOW PRESSURE INJECTION MOLDING OF BORON ADMIXED 316L STAINLESS STEEL FOR ENGINEERING APPLICATIONS Muhammad Aslam 1 , Faiz Ahmad 1 , Puteri Sri Melor Binti Megat Yusoff 1 , Khurram Altaf 1 , Mohd Afian Omar 3 and M. Rafi Raza 2 1 Mechanical Engineering Universiti Teknologi Petronas, Bandar Seri Iskandar, Perak, Malaysia 2 Department of Mechanical Engineering COMSATS Institute of Information Technology, Sahiwal, Pakistan 3 Advanced Materials Research Centre, SIRIM Berhad, Kulim Malaysia E-Mail: Faizahmad@petronas.com.my ABSTRACT This study was conducted to evaluate the effects of elemental boron on densification of 316L stainless steels. Elemental nano size boron (nB) powder of 0.5, 1 and 1.5 wt. % was blended with 316L SS to produce homogeneous feedstock for low pressure powder injection molding (LPIM) process. LPIM molded samples were sintered at 1230 0 C using high vacuum 10 -5 Torr. The Results showed that addition of elemental boron has favorable effects on densification. Addition of 0.5 wt% nano size elemental boron in 316L SS has enhanced densification up to 98.5%. Defect free gears were injection molded and sintered successfully using optimal sintering cycle. Keywords: 316L SS powder, Solvent debinding, scanning electron microscopy, n-heptane, sintering, densification, gear. INTRODUCTION In order to improve the density of sintered parts, external pressure can be applied on parts during sintering process or highly active kinetics path should be provided during sintering through addition of second phase particles[1, 2]. So there are two non-pressure based approaches that can be utilized to enhance the kinetics of sintering process named: liquid phase sintering and activated sintering. Activated sintering is a special process used for lowering the sintering temperature and reducing the sintering time to improve densification of compacts. Although several studies have been conducted on activated sintering on many metals and alloys like: tantalum [3], molybdenum [4], hafnium [5], beryllium [6], aluminum oxide [7] and copper [8] but now main focus of researchers is to modify the sintering cycle for iron and stainless steels [9-12]. In activated sintering, additives are used in small quantity to modify the sintering behavior of base metals and sometimes it is only added in the fraction of 1 wt.% [13]. Additives have exhibited the key role in improving the diffusion process and mobility of grain boundaries [14, 15]. For generalized presentation, German et al.[16] considered two powders one named additive denoted by A and second was named base denoted by B. Additive A was mixed with B for sintering of base material B. They concluded that additive base material B should have higher solubility for additive A to achieve the better diffusion rate. Low solubility of A in B correlates the segregation of layer between the diffused particles grain boundaries and low solubility of A in B minimizes the need for additive required for activation sintering [17]. This consideration is very important and demands the unipolar solubility relationship. Mathematically it can be expressed as:- (1) Where is solubility of B in A and is solubility of A in B. In current research work, loading effects of nano size elemental boron powder on densification of 316L SS was studied and conclusion was made on practical observation during sintering process. RESEARCH METHODOLOGY In order to develop modified PWA 316L SS samples, an experimental protocol was followed as shown in Figure-1 and details are as under:- Figure-1. Schematic diagram of methodology. Feedstock preparation First, Feedstock preparation is an important process in powder injection molding (PIM). The quality of feedstock established the quality of molding, debinding and sintering process. Feedstock must be homogeneous and has maximum metal powder loading with shape stability and strength after molding. Four formulations