STRENGTHENING MECHANISM

Strengthening and Toughening Mechanisms in Metals Made By Direct Metal Laser Sintering/Melting (DMLS/M)



Strengthening And Toughening Mechanisms In Metals Made By Direct Metal Laser Sintering/Melting (DMLS/M)

Introduction

The paper examines the strengthening mechanisms in the alloys. Specifically, this paper explores those alloys which are made by DMLS/M. Additionally, this paper identifies the tensile testing of alloys made by DMLS/M.. Titanium 64, Co-Cr, Al-Si10-Mg and marging steel alloys are discussed in detail in relation to their respective strengthening mechanisms.

The Influence Of Microstructure on Titanium 64, Co-Cr, Al-Si10-Mg and marging steel alloys

Titanium was first discovered in an impure form by Rev William Gregor in England, 1971. It was later given the name titanium (after the titans, in Greek Mythology, the sons of the sky and earth gods) by a German chemist, Martin Kloproth, when he found a dioxide of the metal in rutile, ilmenite, and in many other widely dispersed ores. Titanium oxide with chlorine and coke, then applying extreme heat, producing titanium tetrachloride, which was further reduced with sodium to form titanium. The hunter process successfully produced high quality titanium. (Gaslick , 2002: 105-109)

Eventhough titanium is in abundance in nature, it was not found until the 18th century that it was discovered. This can be explained based on the fact that titanium does not exist by itself but it is found in conjunction with other elements. It is found in the minerals ilmenite and rutile at quantities that it has proven economically profitable to produce them in large quantities while it is also extracted from minerals such as leucoxene, perovskite, brookite, sphene, and anatase.

Most of the titanium alloys are ternary and quaternary and are not binary alloys. Titanium alloys are classified according to the phases present in their microstructure. Alloys that consist mainly of the alpha phase are called alpha titanium alloys, whereas those that contain principally the alpha phase along with small amounts of beta-stabilizing elements like aluminium, gallium, and germanium. (Subramanian et.al 2004: 244-258)

Cobalt-based alloys have been used in demanding applications for as long as investment casting has been available as an industrial process. Arcam's Electron Beam Melting technology competes directly with investment casting and is a viable choice for manufacturing complex parts in cobalt-based alloys(Callister, 2006: 254-259). The majority of investment castings made from the cobalt super alloys are cast in an open atmosphere. With Arcam's Electron Beam Melting process the vacuum atmosphere provides a controlled environment and enables superior material properties in the manufactured parts. CoCrMo alloys are widely used for medical prosthetic implant devices. (Subramanian et.al 2004: 244-258)

Light-weight magnesium alloys have attracted increasing interest in recent years for applications in the automotive, aircraft and electronic industries. The limited ductility of Mg-alloys is basically due to their h.c.p. structure; significant development efforts are thus required to broaden their applicability. (Lawn, 2010: 49-83)

Tempering as an operation of heat treatment has been well known from the Middle Ages. It is used with martensite-quenched alloys. The processes of tempering will be considered here for steels only, sinse steels constitute an ...