The alloy
retains oxidation to 1500 degrees F
(816 degrees C) and has better ruptured creep
and stress properties than the 304 and
304L alloys. This also maintains significant
tolerance to low temperatures. The
higher carbon (0.04–0.10) variant of the alloy
is SS 321H Fasteners. It was
manufactured to boost creep resistance and for
greater strength at temperatures
above 1000 degrees F (537 degrees C). The carbon
content of the fasteners makes for
dual certification in most occurrences.
SS 321 fasteners cannot be hardened by heat
treatment, only by cold operation. It can
be welded and processed easily using normal
welding techniques in the factory. SS
321 Fasteners can be utilized at moderate
temperatures in most diluted organic acids
and at lower temperatures in pure phosphoric
acid and up to 10 percent diluted
solutions at high temperatures. Alloy 321
opposes polythionic acid stress corrosion
cracking in hydrocarbon service. They can also
be used in caustic solutions free of
chloride or fluoride at moderate temperatures.
321 SS Fasteners do not operate well
in chloride solutions, even in small
concentrations, or in the sulphuric acid
service.
ASTM F594 321/321H SS Fasteners
Standard : A193 / A194
Thickness : 0.6 mm THK to 6.00 mm THK
Size Range : 1/16” 1/2” & 1.5MM to 38.1MM
Outer Diameter : 6.00 mm to 60.00 mm