The paper first presents a brief review of development courses of additive manufacturing technology and summarizes the development status and the application fields of additive manufacturing technology, then, according to the manufacturing methods, it focuses on the principles and characteristics of several main additive manufacturing technologies. This paper also analyzes the existing problems and challenges of additive manufacturing technology and its future development trend. This paper aims to provide references for the development direction of additive manufacturing technology in developing countries.

The research status and development trend of additive manufacturing technology

Solidification in spray forming takes place in two distinct steps: typically half of the alloy latent heat is removed rapidly from the droplet spray created by gas atomization; the droplets are then constituted into a billet at deposition where the remaining liquid fraction solidifies relatively slowly. However, within the droplet spray, individual droplets have different thermal and solidification histories and depositing droplets may be solid, mushy, or liquid. Despite many studies of solidification behavior in spray forming, uncertainties and some misconceptions remain on how the solidification conditions in the spray and billet interact to give rise to the characteristic spray-formed microstructure comprising refined, polygonal/equiaxed primary grains with low levels of microsegregation. This article presents a simple numerical model for the spray-formed grain size arising from the deposition of the various droplets in the spray and combines insights provided by the model with previous investigations of the phenomena occurring during and immediately after deposition to propose a comprehensive description of the important solidification behavior during spray forming. Remelting, grain multiplication, thermal and elemental equilibration, and microstructural coarsening are proposed to play a critical role in the evolution of the spray-formed microstructure.

Solidification in Spray Forming

Spray forming combines the metallurgical processes of metal casting and powder metallurgy to fabricate metal products with enhanced properties. This book provides an introduction to the various modelling and simulation techniques employed in spray forming, and shows how they are applied in process analysis and development. The author begins by deriving and describing the main models. He then presents their application in the simulation of the key features of spray forming. Wherever possible he discusses theoretical results with reference to experimental data. Building on the features of metal spray forming, he also derives common characteristic modelling features that may be useful in the simulation of related spray processes. The book is aimed at researchers and engineers working in process technology, chemical engineering and materials science.

Spray Simulation: Modeling and Numerical Simulation of Sprayforming metals

Modelling the shape and thermal dynamics of Ni superalloy rings during spray forming Part 1: Shape modelling – Droplet deposition, splashing and redeposition

Modelling the shape and thermal dynamics of Ni superalloy rings during spray forming. Part 2: Thermal modelling – Heat flow and solidification

A three-dimensional model has been formulated to calculate the shape of the general preform, using vector calculus. The shape of a rod, tube, plate, or irregular preform can be calculated at given spray forming conditions. The shape of a spray-formed rod was analyzed at various spray forming conditions using the three-dimensional model. The effects of spray forming parameters, such as spray distribution parameters, angular velocity of rotation, withdrawal velocity, spray angle, and eccentric distance on rod shape, were analyzed. The most important parameters affecting the shape of rods are the spray distribution parameters and the withdrawal velocity. The dynamic evolution of rod shape with a stepwise variation of the withdrawal velocity during spray forming was investigated. The effect of a stepwise change of the withdrawal velocity was the same as that of the scanning atomizer. The calculated surface profiles were compared with those of spray-formed 7075 aluminum alloy rods prepared on a pilot scale. The calculated results for the surface profiles were in agreement with those of the spray-formed rods.

Hyun-Kwang Seok

Papers

A three-dimensional model of the spray forming method