Study on Thixojoining Process Using Partial Remelting Method

Abstract

Cold-work tool steel is considered to be a nonweldable metal due to its high percentage content of carbon and alloy elements. The application of a new process of the semisolid joining of two dissimilar metals is proposed. AISI D2 cold-work tool steel was thixojoined to 304 stainless steel by using a partial remelting method. After thixojoining, microstructural examination including metallographic analysis, energy dispersive spectroscopy (EDS), and Vickers hardness tests was performed. From the results, metallographic analyses along the joint interface between semisolid AISI D2 and stainless steel showed a smooth transition from one to another and neither oxides nor microcracking was observed. Hardness values obtained from the points in the diffusion zone were much higher than those in the 304 stainless steel but lower than those in the AISI D2 tool steel. The study revealed that a new type of nonequilibrium diffusion interfacial structure was constructed at the interface of the two different types of steel. The current work successfully confirmed that avoidance of a dendritic microstructure in the semisolid joined zone and high bonding quality components can be achieved without the need for force or complex equipment when compared to conventional welding processes.

Investigations on Thixojoining Process of Steel Components

“…The optical microscopic photos taken from the thixo-welded joint are shown in Figure 4. According to the proposal by (Mohammed et al, 2012), the microstructures are created at the interface zone during direct partial remelting processes. Three main regions are apparent in Figure 4 that can be determined by the difference in color and grain size of the full penetration welded joint.…”

“…In addition, a semi-solid join can be used to join a low melting point metal with a high melting point metal (Kiuchi, Yanagimoto, & Sugiyama, 1998;Ridha, Fonna, Huzni, Supardi, & Ariffin, 2013;Yusof, Jamaludin, Abdullah, Hanafi, & Zain, 2012). However, as reported in other studies, there are three possible methods to produce the thixojoining process: combining the forming and bonding as one step (Baadjou, Shimahara, & Hirt, 2006), using a thixotropic metal as the filler for joining materials (Mendez, Rice, & Brown, 2002), and joining two metals in a thixotropic property (Mohammed, Omar, Salleh, Zailani, & Alhawari, 2012). The aims of the present study were to investigate the prospect of joining D2 tool steel to AISI 304 stainless steel and to characterize the interfacial microstructure and metallurgical joints which are accomplished in this novel process.…”

Microstructural Properties of Semisolid Welded Joints for AISI D2 Tool Steel

“…The thixojoining process is developed on the basis of semi-solid metal (SSM) processing, which takes place when the material is between solidus and liquidus temperatures, i.e. when the material shows thixotropic behaviour (Mohammed et al 2012& Alhawari et al 2013.…”

“…In addition, thixojoining can be used to join low-melting-point metal with high-melting-point metal (Kiuchi et al 2000). Recent research activities showed that, there are three methods that can be used in the thixojoining process, namely, combining forming and bonding in one step (Baadjou et al 2006), using a thixotropic metal as fi ller for joining materials (Mendez et al 2002), and joining two metals that have a thixotropic property (Mohammed et al 2013c). The aims of the present study were to investigate the prospect of joining D2 tool steel in the semisolid state and characterize interfacial microstructure and metallurgical joints which are accomplished in this novel process.…”

Microstructural Evolution during DPRM Process of Semisolid Ledeburitic D2 Tool Steel

“…In general, technologies for SSM processing can be divided into two main categories based on the status of the starting material: either a liquid-phase or a solid-phase alloy [4, 5]. Currently, there are a number of methods that can be used to achieve a globular microstructure, such as cooling slope, mechanical stirring, magnetohydrodynamic stirring (MHD), and direct partial remelting (DPRM) [6–8]. …”