UNS S31266

This steel is a super austenitic stainless steel with high chromium, molybdenum, nitrogen content, tungsten and copper, and a PRE value of up to 50. This steel was introduced in 1994. Due to the reasonable ratio of chemical composition of this steel, its mechanical properties, corrosion resistance, welding performance and microstructure stability of the steel are at a high level in the 6% Mo type super austenitic stainless steel.

UNS S31266 Chemical composition：

	Cr	Ni	Mo	W	Cu	N	C	Si	S
\Min	23	21	5.2	1.5	1	0.35	≤
Max	25	24	6.2	2.5	2.5	0.6	0.03	1	0.02

UNS S31266  Physical properties：

Density	8.4 g/cm³
Melting point	1290-1350°C
Thermal conductivity	13.3 W/(m·K)
Coefficient of thermal expansion	12.8× 10^(-6)/°C

UNS S31266 Mechanical properties：

Product type	size/mm	Test temperature/℃	σp0.2/MPa	σb/MPa	δ/%	Charpy (V-notch) impact power/J
Hot-rolled plates	12	12	446	850	60	>300
		-50		—	——	>300
		-196		—	——	>300
Forged Products (Bars))	φ235	300	476	863	80
		20	—	——	——	>3000
		-50	585	1003	80	>300
		-196			—	>3000
	4500	20				211
		-50	—	——		239
	P700	20				151
		-50				127

UNS S31266 Alloy properties：

The 1150°C solid solution treated matrix of this steel is a single austenite structure and there is no σ, x-equal intermetallic phase, carbon and nitride. HuaNickel Compared to 6% Mo type super austenitic stainless steel, the microstructure stability of this steel can meet the needs of products with thick cross-section sizes (e.g. forgings), even if there is a small amount of σ and x-phase precipitation in the core of a large forging

UNS S31266 Uses of alloys：

It can be used in installations, pipelines, and various structural parts in these media environments.

UNS S31266 Process performance：

Welding process: This steel is weldable and can be welded using welding methods common to austenitic stainless steels such as GTAW, GMAW or SMAW.

Heat treatment: This steel can be heated at about 1150 °C, heat preservation and then fast cooling. For products with large cross-sectional sizes, the cooling rate should be sufficient to avoid the precipitation of intermetallic phases.

Relevant standards：

ASTM A182/A182M-2018