K, Santhan Reddy and Sharma, Abhay
(2017)
A computational approach to achieve uniform mechanical
properties along the built-up direction in WAAM component.
Masters thesis, Indian institute of technology Hyderabad.
Abstract
Wire arc additive manufacturing is a promising alternative to the conventional machining
processes which builds large metallic components with low volume and medium
complexity. However, its potential of higher deposition rate itself became the reason to
bring large non-uniformity in mechanical properties at the bottom and top regions of the
component. The reasons for this non-uniformity is the different cooling rates the portions
of the component are undergone through. A finite difference model is developed to
estimate the layer wise variation in thermal cycles and cooling times through which an
understanding is developed on non-uniformity. To estimate the non-uniformity in
mechanical properties, investigations are carried out on hardness. A hardness model is
integrated with the developed thermal model to predict the layer wise hardness,
estimating the non-uniformity along built-up direction. This hardness model is limited to
certain range of mild steels. The experimental and simulation studies are performed on
the single pass multilayer component. From experimental study, non-uniformity is
observed in microstructures and the hardness values along the built-up direction. The
simulated hardness values are in good agreement with the experimental one. Model is
simulated under different process conditions such as maintaining constant baseplate
temperature and diminishing the temperature of the heated baseplate according to the
layer depositions. An understanding is developed to achieve uniform hardness along the
built-up direction and a case is simulated proving it.
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