Table 2 Brief summary of surface modification of Mg-AZ system alloys by FSP available in the literature

AZ31B-H24

H-13

ShD-0.5 inch, PiD-0.25 inch, PiL-0.12 inch

Cylindrical

RS-1200–2000 rpm TS-20–30 in./min

Increase in hardness at low rotational speed and high translational speed.

AZ31

Steel

ShD-10 mm, PiD-3 mm, PiL-3 mm

Conical pin and concave shoulder

RS-1500 rpm and TS-60 mm/min

1. Grain refinement from 92 μm to 11 μm. 2. Super plasticity o AZ31 with an elongation of 268% at 723 K.

AZ31

W18Cr4V-Steel

ShD-16 mm, PiD-5 mm, PiL-2.5 mm,

Cylindrical

RS-950 r/min TS-30 mm/min Number of FSP Passes

Two pass FSP leads to more grain refinement (1.2 μm), increase in ultimate tensile strength (82 Mpa) and percentage elongation (11.9%) as compared to single pass (4.2 μm, 43MPa and 4.3%).

AZ31B-O

Steel

ShD-15 mm, PiD-5 mm, PiL-3 mm

Cylindrical

RS-3000 rpm and 3200 rpm TS-650 mm/min and 550 mm/min Submerged FSP

Submerged FSP leads to more gain refinement in AZ31 alloy by controlling the thermal boundaries of the Process.

AZ61

Steel

ShD-18 mm PiD-7 mm, PiL-5 mm

Conical

RS-1000 mm/min TS-60 mm/min Number of FSP passes

1. Multiple Pass FSP resulted in more grain refinement (7.8 μm) as compared to single pass FSP (12.5 μm),

2. Increase in tensile properties, strength and ductility.

AZ61

Steel

ShD-18 mm PiD-4 mm, PiL-6 mm

Cylindrical

1200 r/min TS- 25–30 mm/min Tool tilt angle 1.5^o

1. Nano size grains produced by FSP combined with raPD heat sink. 2. Three times increase in hardness as compared to base material

AZ61

Steel

ShD-18 mm PiD-16 mm, PiL-8 mm

Concave

RS-500–700 rev/min TS-350 mm/min

Fine grain refinement was observed at 550-600 rev/min. Above this RS the coarser grains were observed.

AZ91

HCHC-steel

ShD-18and12 mm PiD-5 mm, PiL-3.5 mm

Cylindrical

RS-537 rpm - 900 rpm TS-11.71 mm/min–68.28 mm/min

Optimum tool rotational speed and optimum tool traverse speed for obtaining maximum hardness, minimum corrosion rate and min area surface.

AZ91

2344-steel

ShD-15 mm PiD-4 mm, PiL-2.5 mm

Cylindrical shoulder and square pin

RS 900 rpm TS-40 mm/min Tilt angle 3^o

1. The nugget or stir zone lies on the advancing side as majority material flow occurs on the advancing side.

2. The width of the stir zone is related to material deformation and micro structure evolution.

AZ91

Steel

ShD-18 and 12 mm PiD-4 mm, PiL-5 mm and 3 mm

Cylindrical

RS800 rpm TS-60 mm/min Two pass FSP

Two pass FSP leads to more refinement of grains, increase in tensile strength and percentage elongation (312 MPa and 29.4%) as compared to one pass FSP (294 Mpa and 25.2%).

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