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Federal Highway Administration Research and Technology
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Publication Number: FHWA-HRT-09-044
CHAPTER 2. RESEARCH COMPONENT #1: 2304 SS REINFORCING BARS IN CHLORIDE-CONTAMINATED ENVIRONMENTS
The objective of this component of the study was to expand the scope of the companion FHWA/Florida Department of Transportation (FDOT)-sponsored research project by investigating the possible susceptibility of stainless alloy 2304 SS (UNS-S32304) to stress corrosion cracking under conditions relevant to reinforcing steel in concrete (task 1.1) and conducting both accelerated and long-term corrosion experiments on stainless alloy 2304 reinforcement (task 1.2).
The microstructure of duplex SS such as 2304 is comprised of approximately equal amounts of ferrite and austenite phases. Table 1 lists information for this alloy including the supplier, the as-received surface condition, and the pitting resistance equivalent number (PREN, also referred to as PRE), as defined by the following equation:
Likewise, table 2 lists the composition of this alloy. In general, duplex SS exhibits relatively high strength and ductility as well as beneficial corrosion properties including resistance to sensitization-induced intergranular corrosion, and high resistance to stress corrosion cracking. All experiments were performed using #5 (16-mm-diameter) bars.
Note: C = carbon, Mn = manganese, P = phosphorus, S = sulfur, Si = silicon, Cr = chromium, and Ni = nickel.