This content include Friction stir additive manufacturing,friction stir welding , additive manufacturing , need , steps, working principle, result, deffect, process parametre
2. Contain
• Introduction of Additive Manufacturing.
• Introduction of friction stir welding.
• Friction stir additive manufacturing (FSAM).
• Need of FSAM.
• Working principle.
• Step of FSAM.
• Fundamental of process.
• Process variable .
• Variation in Grain Size.
• Hardness.
• Tensile strength.
• Defect
4. Additive Manufacturing
• AM is around thirty years old manufacturing technology which is still under
evolution and has established utility in visualizing designs as well as
manufacturing advancements.
• AM is a process where materials are joined in a layered fashion for fabricating
components directly from their 3D models.
• AM process chain stems from its general working principle and consists of six
major stages.
(a) preparing 3D CAD model (b) convert to STL
(c) slicing (d) material deposition
(e) generating physical models (f) post processing.
5.
6. Why additive?
• Less/no material wastage
• Dimension accuracy
• Complex geometry
• Inner cuts possible
• 3d printing Fairley cheap
• Reduce tool costing
8. Working principle
• Work pieces to be joined are rigidly fixed.
• Wear resistant tool of different material rotating at high speed. Material deform
plastically due to friction heat.
• Rotation of tool leads to stirring and mixing.
• Mixing of material at the joining region below their melting points.
• Good mechanical properties and low distortion due to low heat input.
9.
10. Why Friction stir welding
• Low heat input.
• Better mechanical properties.
• Dissimilar material can be joint.
• High productivity.
• Low distortion and shrinkage.
• No consumable and no filler.
12. Need of FSAM/ Resistance in AM
• Contamination of substrates in AM.
• Solidification defect in AM.
• Less structural properties in AM.
• Defect like pores, Shrinkage cavity ,inclusion in AM.
• High amount of Power required in AM.
• Non homogeneous microstructure.
• Directional variation in mechanical properties.
• Stepping.
• Restraint up to production level.
• Need for close controlled chamber with inert gas.
13. • FSAM utilizes the principle of
layer-by-layer AM.
• Friction stir lap welding is generally
utilized to additively join the metallic
layers.
• In its conventional form,
no consumable tool is inserted into
a stack of overlapping sheets/plates
and FSLW is carried along the defined direction.
• The heat necessary for the joining of layers is obtained due to friction and plastic
deformation of the work material.
Working principle of friction stir additive
manufacturing
15. • Step 1 Initial preparation : First of all, the plates/sheets to be additively
manufactured using FSAM are prepared in terms of flatness. These plates are
made in the proper dimensions as desired and cleaned with acetone.
• Step 2 Stack metal sheets: Initially, two plates/sheets are overlapped one over
the other as per the orientation of the desired build.
• Step 3. Perform one complete FSLW run: FSLW is performed with suitable
process parameters. After completion of the first run, if the desired build height
is achieved, then it is the final component. Otherwise, the process progresses to
step 4.
• Step 4. Flatten upper build surface: If the desired build height is not achieved,
then first flatten the upper surface by machining and then additional layers are
deposited over the surface through step 2 and 4.
16.
17. Fundamental of process
• FSAM is a customized process of friction stir lap welding (FSLW) in which its
repeatedly perform to add multiple layer to build a desire thickness.
• Initially, when two layers are added via FSLW, at the top surface of upper layer
(say layer 2), material flow is governed by tool shoulder. while bottom surface of
layer 2 and top surface of layer 1 is governed by tool pin.
• During additive joining of next layer (say layer 3), the top surface of layer 3 is
shoulder driven and bottom surface of layer 3 and top surface of layer 2 are pin
driven.
18. • In this way, material flow at the top surface of layer 2 is initially governed by tool
shoulder and then in further additive joining of third layer, it is governed by tool
pin.
• similar fashion, different layers of the build experiences different thermal
exposures from bottom to top direction of the build.
• FSAM, material is vigorously stirred, plastically deformed and then it undergoes
dynamic recrystallization.
19.
20. Process Variables
• The process variables of FSAM are similar to those of FSW/P.
• RPM: responsible for heat generation is important parameter , higher the RPM
more the heat is generated.
• Tool shoulder and pin dimension : This two are majorly contribute in process ,
shoulder generate 80% of heat and pin function is to stir a material.
• Travelling Speed: Higher the travel speed lower heat generation. There is best
combination of lower travelling speed and higher RPM for generating more heat.
• Tilt angle: this variable leads a upward pressure for stirring material. And also try
to increasing area of tool to work piece.
21. • Axial Force : Axial force is another important parameter for FSAM and FSW/P
processes. A lower axial load leads to poor consolidation of plasticized materials,
resulting in tunnel defects.
• Plunge depth: how much shoulder insert in work piece, this variable responsible
to the ensure the contact of shoulder to the Work piece.
22. Grain size variation
• For understanding a concept of grain size ,
taking case study of magnesium specimen as per
figure. We take four specimen.
a) Top up layer (four layer)
b) Interface of four and third layer
c) Top down layer (First layer)
d) TMAZ region
23. Location Grain size (μm)
Layer 4 0.7
Interface 4 and 3 0.98
Layer 1 0.84
TMAZ 1.1
a) Layer 4: seen in table lowest Grain size in layer 4 , because of four layer has no further
upward layer on above so grain growth restriction there. And this layer
experienced stirring So there are grain refinement take place .
These two are reason for that getting lower grain size.
24. Interface of Layer 3 and Layer 4: we seen that grain size is higher then layer 4 and
layer 1 , because this interface experience both
shoulder and pin and 80% of the heat is generated
through shoulder so because of that grain growth
are there.
TMAZ: This region is highest grain size because of that area is not experienced
the grain refinement through shoulder and heat are transfer to this area
so the grain growth are there.
Layer 1: layer 1 has comparatively higher grain size to layer 4 , because as we move
Top layer to bottom layer there are annealing process executed
so heat of the upper layer Experienced in lower layer so Grain growth is there.
And also shoulder is not gone through in 1 layer so there is no Grain Refinement.
25. • Variation in grain sizes takes place in different regions of the build.
• This variation is dependent on the type of material (heat treatable or
non–heat treatable) under investigation.
• The main reasons behind these variations are multiple and different
thermal exposures, variation in material flow.
• The top layer is shoulder driven, while the bottom layer material flow
is pin driven.
• intermediate layer experience the both PIN and SHOULDER both material flow
type.
26. Hardness
• This graph shows that comparison of base
metal hardness to the built component hardness
to the Depth.
• Here doted line shows a base metal hardness
And square curve shows the built part hardness.
• So there are nearly 23% more hardness
Achieved via Friction stir additive manufacturing.
Reason behind that the grain refinement, finer
Grain part has more hardness.
27. Tensile strength
• This case study about aluminium 5083 alloy
Which perform a FSAM.
• Graph is show that the comparison of
Tensile strength of build and base metal part.
• Black line indicate the base metal graph
And red one indicate the build part.
• An increase in tensile strengths for FSAM
was found. It can therefore be concluded
that microstructural reformation is the
major contributor to strengthening achieved.
28. Defect in FSAM
• There are most common defects are include hook formation, cavities, crack, kiss
bond formation.
• Hook defect: the hooking defect, which was normally observed at a lower
magnification, was most evident at he TMAZ of the AS. where the interface of the
work pieces was pulled up into the top work piece. Also, the hook was inclined
upward toward the weld surface.
• Kiss bond defect: The kissing bond defects were a result of insufficient mixing at
the interface of the work pieces that led to the presence of separated interfaces
with entrained oxide layers.
29. • Cavities: it is a basically volumetric empty space, no align material to the joint
direction, and it is made because of reduction in a pressure at AS side and it
turned up into a tunnel.
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