UNS S31277

HuaNickel UNS S31277 is also a 7Mo type super austenitic stainless steel, the high chromium, molybdenum and nitrogen in the steel make this steel have excellent pitting corrosion resistance, crevice corrosion resistance, etc., high nickel, molybdenum, nitrogen content provides the steel with the ability to resist the corrosion of reducing acid media, nickel and nitrogen two elements make the steel resistant to stress corrosion and alkali corrosion, and the high chromium nitrogen content in the steel makes the steel overcome some of the adverse effects of high molybdenum, and has good resistance to corrosion of chloride-containing acid media.

UNS S31277 Chemical composition：

	Cr	Ni	Mo	Cu	N	C	Si	Mn	S	P
Min	20.5	26	6.5	0.5	0.3	≤
Max	23	28	8	1.5	0.4	0.02	0.5	0.3	0.01	0.03

UNS S31277 Physical properties：

Densityp/g·m-	Thermal conductivity/W·(m·K)-1			Resistivity(room temperature)/μΩ ·cm	Specific heat capacity(room temperature) /J(kg·℃
	21℃	100℃	300℃
8.02	10.1	12.1	16.2	100	454

UNS S31277 Mechanical properties：

σb/MPa	σp0.2/MPa	δ₅/%	HRB
655	310	42	90
827	404	50	95
862	469	50	95
724	345	60	88

UNS S31277 Alloy properties：

HuaNickel UNS S31277 steel has a typical austenite structure in the solid state, and the steel will have σ equal intermetallic phase precipitation in the aging or sensitized state at 600~930 °C, but because the carbon content of this steel is very low, the carbide precipitation is very small; Despite the high nitrogen content, nitrides such as CrzN are not formed at high temperatures.

UNS S31277 Uses of alloys：

UNS S31277 alloy has been used to make the I-stage turbine rotor blades of aviation turbine engines, and has passed the test flight and life bench test with good performance.

UNS S31277 Process performance：

Welding process: HuaNickel UNS S31277 steel products can be welded using the existing welding processes common to austenitic stainless steels, such as tungsten gas arc welding (GTAW), gas arc welding (GMAW), manual arc welding (SMAW), submerged arc welding (SAW) and plasma arc welding (PAW), etc. Heat treatment of parts: Parts are generally used in the as-cast state, and standard heat treatment must be carried out if diffusion coating is used.

Heat treatment: Although HuaNickel UNS S31277 steel also has the sensitivity of precipitation σ equal intermetallic phases, however, due to the reasonable ratio of alloying elements in the steel, when the steel contains 22% Cr, 27% Ni, 7% Mo and 0.35%N, its σ phase dissolution temperature is 1095 °C, and the σ phase solution temperature of 1095 °C is still low in super austenitic stainless steel and 6% Mo iron-nickel-based corrosion resistant alloy (N08031), which helps to choose a lower solution treatment temperature. It can also achieve the effect of making the σ equal and completely dissolved.

Relevant standards：

ASTM A240/A240M-2020