3Cr17Ni7Mo2N, austenitic stainless steel, codename 318, was developed in 1968 by Shanghai Research Institute of Materials, Shanghai No. 5 Iron and Steel Works, Chongqing Steel Works, Sichuan Petroleum Management and Design Institute [SCALE STEEL]jointly for the Sichuan gas field natural gas contains more hydrogen sulfide, which causes serious corrosion to the equipment.
C 0.22~0.30 Cr 16.00~18.00 Ni 6.00~8.00
Si 0.80~1.60 P ≤0.035 Mo 2.00~2.50
Mn ≤1.00 S ≤0.30[SCALE STEEL] N 0.15~0.22
solution heat treatment 1130℃±10℃, holding for 2h, water quenching
strength of extension MPa ≥785
yield MPa ≥420
percentage elongation after fracture % ≥35
reduction of area% ≥40
hardness HRC ≤24
is a low cost material developed for hydrogen sulfide corrosion resistance. It can resist hydrogen sulfide uniform corrosion, sulfide stress cracking resistance, hydrogen embrittlement resistance, pitting resistance, reducing [SCALE STEEL]medium corrosion resistance.
The 318 is typically used to manufacture sulfur [SCALE STEEL]resistant wellheads, valves, stems, and fasteners for applications where H2S partial pressures exceed 1MPa.