254 SMO

HuaNickel 254 SMO steel series is one of the earliest super austenitic stainless steels developed in the 70s of the 20th century. It not only has good overall corrosion resistance in reducing media, but also has excellent resistance to pitting corrosion, crevice corrosion and other local corrosion in chloride-containing media, and at the same time, due to the strengthening effect of nitrogen, the strength of this steel is also higher than that of general chromium-nickel austenitic stainless steel.

254 SMOChemical composition：

	Cr	Ni	Mo	Cu	N	C	Si	Mn	P	S
Min	0.5	17.5	–	0.5	0.18	≤
Max	1	18.5	6.5	1	0.22	0.02	0.8	1	0.03	0.01

254 SMOPhysical properties：

Densityg/cm³	Specific heat capacity/J·(kg·K)-1	Linearexpansioncoefficient(20~100℃)/10-5·K-1	Thermalconductivityλ/W·(m·K)-1	Magneticpermeability(20℃) μ/H·m-1
8.0	500	16.5	13.5	1.01

254 SMOMechanical properties：

temperature/℃	Mechanical performance
	σb/MPa	σp0.2/MPa	δ₅/%	hardness(HB)	ak/(J·cm-2)
20	≥650	≥300	≥35	≤210	120
50	≥635	≥270
100	≥615	≥235
200	≥560	≥195
300	≥525	≥175
400	≥510	≥160

254 SMOAlloy properties：

The structure of HuaNickel 254 SMO steel is a single austenite structure in the solid solution state, but it is affected by the thermal experience, such as carbide and intermetallic phase compounds will precipitate in the heat affected zone during thermal processing and after welding, because the carbon content in the steel is very low, it is mainly the precipitation of intermetallic phases such as x-phase, σ phase, η phase and Cr₂N

254 SMOUses of alloys：

This steel is mainly used for equipment and components that are resistant to seawater corrosion; bleaching units in the pulp and paper industry, structural parts for flue gas desulfurization; Containers and pipelines for handling and conveying halogen-containing media, as well as oil refining units, etc.

254 SMOProcess performance：

Welding process: This steel has good welding performance, and can be welded by the common method of welding stainless steel, without preheating before welding and heat treatment after welding.

Heat treatment: The heat treatment process of this steel is to heat it to 1150 °C and then cool it quickly.

Relevant standards：

ASTM A240、ASME SA240、ASTM A276、ASME SA276、ASTM A312/ASMES A312; 4、ASTM A182、ASME SA-182