[ Duplex Bar ]
[ Duplex Bar ]
bar are shown in Figure 3 . In general , hardness values of the rolled and forged bar material are lower than material property requirements , are given only for guidance and for internal requirements , the upper limit is a maximum of 28HRC . The hardness results for the rolled specimen from the external surface to centre of a final diameter Ø140 , Ø160 , and Ø180 are virtually the same as the forged specimen , though some hardness values obtained in the forged performed at the right angles are slightly different and somewhat less but still within specification . This is particularly at the mid-radius and centre . It is worth noting that the variation in the hardness values for the rolled specimen is slightly low relative to the forged specimen .
Conclusions Conclusions can be drawn as follows :
• The shape of austenite in the forged bar shows somewhat more serrated grains relative to the rolled bar .
• A large quantity of secondary austenite precipitates showed more in the forged bar .
• The average austenite spacing values for the rolled bar are small , in the range of 29-32 μm and for the forged material in the range of 42-43 μm .
• The tensile results for the rolled bars are somewhat higher than the forged ones .
• The toughness results of the rolled bars in the longitudinal and transverse directions are greater than the forged bars .
• Hardness values for the rolled and forged bars are virtually the same and lower than material property requirements .
References
[ 1 ] https :// www . alleima . com / en / technical-center / materialdatasheets / bar-and-hollowbar / bar / sanmac-2205 /
[ 2 ]
ASTM A479-14 , Standard Specification for Stainless Steel Bars and Shapes for Use in Boilers and Other Pressure Vessels
[ 3 ]
ASTM A276-15 , Standard Specification for Stainless Steel Bars and Shapes
[ 4 ]
ASTM A182-14a , Standard Specification for Forged or Rolled
Alloy and Stainless Steel Pipe Flanges , Forged Fittings , and Valves and Parts for High-Temperature Service
[ 5 ]
ASTM E 381ASTM E407 , Standard Practice for Microetching Metals and Alloys
[ 6 ]
Recommended Practice DNV- RP-F112 , October 2008
[ 7 ]
ASTM A370 , Standard Test Methods and Definitions for Mechanical Testing of Steel Products
About the author
Dr Munir Al-Saadi has
worked for Alleima ( formerly Sandvik Materials Technology ) in Sandviken , Sweden , since 2007 as a development engineer in R & D Metallurgy , focusing on re-melted material for medical applications , super-duplex and nickel alloys for oil & gas applications . Today , he is R & D Senior Engineer in the Tube , Metallurgy & Product Development department .
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