Iron Spark Plasma Sintering (SPS): Part One

Spark Plasma Sintering (SPS) is a sintering technique which is well matched to mechanically milled materials such as tool steels due to its low temperature and short cycle time.
Tool steels have been specifically manufactured to exhibit exceptionally high strain hardening, a characteristic which can be undone by high temperature sintering processes such as hot isostatic pressing. Continue reading

Superplasticity of Aluminum Alloys: Part Two

Investigations into the superplasticity possibilities of aluminums can lead to many potential gains in finding lighter yet capable materials in terms of strength performance.
This article covers the high-temperature deformation behavior of 5083 at different annealing temperatures and yields some interesting conclusions. Continue reading

Superplasticity of Aluminum Alloys: Part One

It is known that superplasticity refers to the ability of a material to demonstrate under tensile tests very high uniform deformation more than several hundreds percents without visible necking. There are two basic requirements in order to achieve superplastic flow in a polycrystalline material. First, the material must have a very small and stable grain size less than 10 μm. Second, superplasticity is achieved only at relatively high temperatures above 0.5Tm (where Tm is the absolute melting temperature) because superplasticity is diffusion-controlled process. Continue reading

The Nitrocarburizing Process: Part One

Nitrocarburizing, by definition, is a thermochemical treatment that is applied to a ferrous object in order to produce surface enrichment in nitrogen and carbon which in turn form a compound layer.
The composition, function and control of the furnace atmosphere are of crucial importance for the result of all hardening and thermochemical operations. Continue reading

Low Temperature Carburizing of Austenitic Stainless Steel: Part One

Although austenitic stainless steels are among the most commonly applied corrosion resistant steels challenges exist related to their relatively poor surface hardness and wear resistance.
Low temperature carburizing presents an effective solution to these challenges by increasing surface hardness through a carbon rich diffusion zone which does not compromise the corrosion resistance of the material. Continue reading

The Direct Nickel Process

Using nitric acid as a leaching agent the direct nickel process can treat all types of nickel ore and produces a single flow sheet for a number of final saleable products.
As an atmospheric hydrometallurgical process the direct nickel process has an impressive recycle and return statistic meaning 95%+ of the nitric acid is re-used, therefore providing good environmental incentive. Continue reading

Semi-Solid Rheocasting of Alumina Alloys: Part One

Aluminum is well established at the front of the pack with regards to providing the technological answer to the increasing challenges of light weighting whilst maintaining integrity of the material for the desired applications.
Semi solid rheocasting is a development within the casting sector which enables improved quality in die casting without increasing cost. Continue reading

Vacuum Brazing: Part One

Vacuum brazing is categorized as a technique by its protected sealed environment under vacuum and extremely high temperatures greater than 800°C.
The main advantages of using vacuum brazing include achieving high integrity hermetic joints with minimal distortion. Continue reading

Lean Alloy Steels

Rising prices of certain alloying elements such as nickel and molybdenum have driven recent work on lower priced replacements for austenitic stainless steels.
Progress has been made in finding suitable replacements but there are some key open questions remaining regarding the performance of the materials in specific applications. Continue reading

Sinter Rotary Forging: Part One

Sinter rotary forging is one of the prominent sinter forming processes and uses pressed and sintered metal powder preforms as starting material. The sinter forming technique combines the advantages associated with two well-known techniques, namely powder metallurgy and conventional forming. Continue reading