Confidential
Introduction of Flap Peening
宏達檢測有限公司
HD Inspection Co., Ltd.
2022/09/26
Benefits of Shot Peening
Confidential
 The shot peening will generate surface
compressive stress.
 To improve the fatigue life.
 Changing the surface tension stress on heat
affected zones (HAZs) of base metal after
welding into compressive stress, which can avoid
the stress corrosion cracking of 300 series
stainless steel.
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珠擊法(Shot Peening)
Confidential
• Small steel balls are sprayed by high pressure air or
rotating impeller to impact the material surface to
create dimples. These dimples will form surface
compression residual stress.
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拍擊法(Flap Peening)
Confidential
• The small balls are mounted on the flapper. The flapper
fixing on grinder tool can be rotated to impact the
material surface to create dimples. These dimples will
form surface compression residual stress.
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殘留應力量測
(Measurement of Residual Stress) Confidential
• Portable X-ray Residual Stress Analyzer PULSTEC μ-360
Residual Stress of 304H stainless steel
項目
Residual (MPa)
(+:tension stress ; -:compression stress)
Inner Surface
Outer Surface
Before flap peening
+791
+734
After flap peening
-706
-801
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拍擊珠擊步驟
(Procedure of Flap Peening)
Confidential
(1)Measuring the residual stress before flap peening ： To
measure the residual stress of HAZ before flapper peening.
(2)Applying flap peening：To apply flapper peening on welds and
HAZs of specimen.
(3)Measuring the residual stress after flap peening：To measure
the residual stress of HAZ after flapper peening.
Acceptance of Compression stress after flap peening：< -500MPa
for 300 series stainless steel.
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