SAF 2906

HuaNickel SAF 2906 is a new super duplex stainless steel, which is a further improvement of 00Cr25Ni7Mo4N steel. Compared with HuaNickel 00Cr25Ni7Mo4N, the amount of molybdenum and chromium in this steel is reduced, and its pitting corrosion equivalent value is slightly lower than that of 00Cr25Ni7Mo4N, but the composition is more balanced and the thermal stability is improved. This steel is resistant to alkali medium corrosion, various local corrosion, such as intergranular corrosion, stress corrosion, pitting corrosion, crevice corrosion, etc., and the welding performance is good, and the strength is about 3 times that of ordinary chromium-nickel austenitic stainless steel.

SAF 2906 Chemical composition：

	Cr	Ni	Mo	N	Cu	C	Si	Mn
Min	–	–	–	–	–	≤
Max	29	6	2	0.4	0.5	0.03	0.5	1

SAF 2906 Physical properties：

Densityp  /g·cm-3	Linear expansion coefficienta/×10-6·℃-1			Thermal conductivityλ/W·(m·℃)			Specific heat capacity/J·(kg·℃)-1			resistance/μΩ ·m
	30~100℃	30~200℃	30~300℃	20℃	100℃	300℃	20℃	100℃	300℃	20℃
7.7	11.5	12.0	12.5	13	14	18	480	500	560	0.81

SAF 2906 Mechanical properties：

Pipe wall thickness/mm	σp0.2/MPa	σb/MPa	δ₅/%
<10	≥650	≥800	≥25
≥10	≥550	≥750	≥25

SAF 2906 Alloy properties：

In the process of high temperature (hot working, hot forming, welding, heat treatment, etc.) cooling, there will also be σ, x, R and other intermetallic phases and nitride precipitation, which will have an adverse effect on the mechanical properties and corrosion resistance of the steel, but because this steel is compared with the aforementioned SAF2507, the molybdenum in the steel is low, and the nitrogen is high, so the formation of σ equality is slowed down, and compared with HuaNickel 00Cr25Ni7Mo4N, this steel has a high microthermal stability.

SAF 2906 Uses of alloys：

SAF 2906 steel has the characteristics of high strength and high toughness. The main uses are: pipes for pipeline systems including evaporator pipes in caustic soda production, heat exchanger pipes in alumina production and pipes in some units of zirconia plants, as well as equipment and components with high corrosion resistance requirements for pitting and crevice corrosion.

SAF 2906 Process performance：

Welding performance: SAF 2906 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 process suitable for welding SAF 2906 steel is MMA and TIG welding, 1% ~ 2%N₂ need to be added to the welding protective atmosphere, ESW welding can be used for pole surfacing welding of tube sheet.

Heat treatment: fast cooling after heating and heat preservation at 1040~1080°C (water cooling or air cooling according to cross-sectional size).

Relevant standards：

ASTM A240/240M-2018