What is S32906

What is S32906

S32906 stainless steel is a new super duplex stainless steel, which is a further improvement of 2507 duplex steel. Compared with 2507 duplex steel, this steel has reduced molybdenum and chromium content, and its pitting resistance equivalent value is slightly lower than that of 2507 duplex steel, but the composition is more balanced and the thermal stability is improved.

S32906 stainless steel is resistant to alkali medium corrosion and various local corrosion, such as intergranular corrosion, stress corrosion, pitting corrosion resistance, crevice corrosion resistance, etc. It has excellent performance, and has good welding performance, and the strength is about 3 times that of ordinary chromium-nickel austenitic stainless steel. S32906 stainless steel can be used in caustic soda and aluminum chloride production pipelines and heat exchange equipment, such as evaporators, heat transfer tubes of heat exchangers, etc. The corresponding grade of S32906 stainless steel in China is 00Cr29Ni6Mo2N, and some are also called SAF2906.

Chemical composition of S32906 duplex steel (%)
Chemical composition label	Grades	C max	Si max	Mn max	S max	P max	Cu max	Cr	Ni	Mo	N
00Cr29Ni6Mo2N	SAF 2906 UNS S32906	0.03	0.50	1.00	0.03	0.03	0.8	28/30	5.8/7.5	1.5/2.6	0.3/0.4

The microstructure of S32906 is similar to other super duplex stainless steels. The solid solution state has a ratio of α/γ close to 1, and there will also be σ during the cooling process at high temperatures (hot working, hot forming, welding, heat treatment, etc.) , Χ and other intermetallic phases and nitrides precipitate, which have a negative impact on the mechanical properties and corrosion resistance of the steel. However, compared with super duplex 2507 pipe, SAF2906 stainless steel has low molybdenum and high nitrogen, which slows down the formation of equal σ , But this steel has higher structural thermal stability.

Mechanical properties of S32906 stainless steel
Temperature/℃	Pipe thickness/mm	σ0.2/MPa	σb/MPa	δ/%
Room temperature	＜10	≥650	≥800	≥25
≥10	≥550	≥750	≥25
100	＜10	≥550	≥750	≥25
≥10	≥500	≥730	≥25
200	＜10	≥470	≥720	≥25
≥10	≥430	≥700	≥25
300	＜10	≥450	≥710	≥25
≥10	≥410	≥690	≥25

Since α+γ duplex stainless steel has higher yield strength and tensile strength than austenitic stainless steel, cold forming requires greater external force. For example, when the S32906 pipe is expanded and connected to a pipe, the expansion force should be higher than that of the austenitic stainless steel. Generally, to prevent leakage, the tube and the tube sheet need to be welded after the expansion. Similarly, cold bending of S32906 stainless steel also requires greater external force. Since S32906 stainless steel has a duplex structure, its cutting speed during machining is also lower than that of austenitic stainless steel. S32906 stainless steel has good weldability. Due to the formation of γ in the welding heat-affected zone, the weld has good toughness, strength and corrosion resistance. The suitable process for welding S32906 is MMA and TIG welding. The welding protective atmosphere needs to add 1% -2% N2, ESW welding can be used for strip surfacing of tube sheet.

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Posted by Kaysuns, the best stainless steel pipe fittings supplier.