Friction Stir Processing ofAluminum Casting Alloys:

Microstructure Manipulation/SurfaceComposite Fabrication

Ning Ning SunSunAdvisor: D. Advisor: D. ApelianApelian

Born in Qingdao, east coast ofChina (known for TsingTao Beer)

B.S. in MSE (July 2007), fromHefei University of Technology

M.S. Candidate ACRC(started September 2007)

Interests:• Western and Chinese music• Piano• Jogging

NING SUN

QINGDAO, CHINA

Outline

• BackgroundPrinciples, Applications, Challenges

• Objectives• Experimental Plan• Expected Outcomes• Schedule

Background

FSP is a relatively new processingmethod that was developed in 1997by R.S. Mishra et al* based on the

principles of friction stir welding (FSW-invented by TWI (UK) in 1991)

* High strain rate superplasticity in a friction stir processed 7075 Al alloy

Background

Credit: J.-Q.Su et al.

A rotating, non-consumable tool, comprising of a profiled pin and a larger shoulder plunges into the surface of the work-piece, and then travels along the work-piece

Background

Characteristics of FSP

• Solid-state• Thermo-mechanical in nature• Severe plastic deformation experienced

Background

Credit: I.Charit and R.S. Mishra

Grain size refinedfrom 200 µm to0.5 µm-12 µm.

Background

Grain Boundary Misorientation Angle Shiftsfrom a Low Value to a High One

a) b)

Credit: OIM result from W.M. Thomas et al

Background

High Strain Rate Superplasticity Achievedat Low Temperatures

Data of Mishra et al’s work in comparison with Xing’s

Background

Hardness Data (2014 Al alloy)

Credit: Y.J. Kwon et al

Background

Tensile Data (2014 Al alloy)

Credit: Y.J. Kwon et al

Background

Fatigue Data (A356)

Credit: By S.R. Sharma et al

Background

• Tool geometry• Tool wear• Overlapping• Microstructural stability

INFLUENCING PROCESSING PARAMETERS

Outline

• Background• Objectives• Experimental Plan• Expected Outcomes• Schedule

Objectives

Explore and Evaluate the Feasibility ofFriction Stir Processing in AluminumAlloys, Specifically To:

1. Manipulate the microstructure to refine or strengthen locally

2. Investigate the potential of FSP to form a particle-reinforcedzone in standard Al cast components, by mixing and creatingstrengthening particles, and establish optimum processingconditions; i.e., local composite fabrication via FSP

Experimental Plan

Alloys: work-piece material

• A356(6Si,0.2Fe,0.2Cu,0.1Mn,0.4Mg,0.1Zn,0.2Ti,other)

• A380(9Si,2.0Fe,3.0Cu,0.5Mn,0.1Mg,3.0Zn,0.5Ni,0.35Sn,other)

• A206(0.1Si,0.15Fe,4.2Cu,0.3Mn,0.3Mg,0.01Zn,0.2Ti,other)

Experimental Plan

FSP machine

HAAS Mill DrillCenter

> 10,000 RPM> 2000 IPM

Experimental Plan

Tool material:

Tool steel

Tool geometry:

Shoulder: 18mm Diameter Pin: Tilt angle ≈ 2.5-3 degree with

different tool shapes

Experimental Plan

Max diameter(mm)

Min diameter(mm)

Screw

Column 8 8 Y

Column 8 8 N

Taper 8 6 Y

Taper 8 6 N

Tool Shapes

Experimental Plan

Second Phase Particles Consideredfor Localized Composite Fabrication

> SiC

> TiC

> Cr3C4

> Al2O3

Experimental Plan

Processing:

• Confirm microstructure evolution during FSP

• Surface composite fabrication via FSP

Experimental Plan:microstructure evolution

Confirm Microstructure Evolution During FSP:

500, 800, 1250, 1750, 2000 (rpm)

100, 150, 200 (mm/min)

Experimental Plan:composite fabrication

Particle-reinforced Zone Developed by:

• Mixing-in strengthening particles

• Forming strengthening particles by in-situ chemical reactions

Experimental Plan

Mixing-in Strengthening Particles:

I. Filling into the groove on the surface of the work-piece

II. Painting slurry onto the surface of the particle-reinforced zone

III. Injecting powder into the FSP zone

Experimental Plan

Forming Strengthening Particles by in-situChemical Reactions:

I. Alloy + Reactant + Catalyst Particles + Secondary product

II. Pin tool + Reactant + Catalyst Particles + Secondaryproduct

III. Reactant (1) + Reactant (2) + Catalyst Particles + Secondaryproduct

Experimental Plan

FSP Parameters for Surface Composite Fabrication:

500 rpm, 800 rpm

20 mm/min, 80mm/min

H 1mm, 1.7mm, 2.3mmH

Outline

• Background• Objectives• Experimental Plan• Expected Outcomes• Schedule

Expected outcomes

Microstructure Evolution During FSP

Grain size refined from several hundred µm orseveral ten µm … to 0.5 µm-12 µm

Grain boundary misorientation angle shiftsfrom low to high

Enhanced mechanical properties

Expected outcomes

Surface Composite Fabrication via FSP

Particle reinforced zone is created via FSP

Structural integrity at localized interface

Enhanced mechanical properties

Schedule

Sep '07-Dec'07

Jan '08-May'08

Jun '08-Dec'08

Jan '09-March '09

April '09-June '09

Critical Lit Review (I) (I)

Project Planning (I)

Finalize Exp. Plan (I) (I)

Execute Exp. Part I (II) (II)

Execute Exp. Part II (II) (II) (II)

Modeling (III) (III) (III)

Thesis Write-up (IV)

Thesis Defense (IV)

Thank you for theopportunity andyour attention