S32707 1.4658 Duplex Stainless Steel

UNS S32707 is a hyper-duplex stainless steel, a high-alloy duplex steel with a PRE value of min. 48*. The grade is characterized by excellent chloride corrosion resistance, combined with very high mechanical strength.

S32707 is particularly suited for use in aggressive environments such as hot chlorinated seawater and for highly acidic, chloride containing media. S32707 has better resistance to pitting and crevice corrosion and higher mechanical strength than all super-duplex stainless steel grades available on the market.

Stainless Seamless Fluid Pipe Quality Control

1. Raw materials pipe blank quality classification: high quality, medium, economical
2. Raw materials inspection after receive in factory
3. After pickled, tube will be grinded careful to less defect
4. Multiple cold drawn/rolled process for precision dimension
5. Standard heat-treated of continuous annealed/solution for better property, intergranular corrosion
6. Full Inspection: ET, UT, Hydraulic Test, Penetration Test, Grinded, Sand Blast, Print Making

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We also can supply other kinds of:

• Seamless Stainless Steel Pipe & Tube
• Welded Stainless Steel Pipe & Tube
• U Type Stainless Steel Pipe & Tube
• Coil Type Stainless Steel Pipe & Tube(Max 300meter), seamless or welded
• Annealed Pickled AP Stainless Steel Pipe & Tube (Ra ≤5μm)
• Bright Annealed BA Stainless Steel Pipe & Tube (Ra ≤8μm)
• Mechanical Polished MP Stainless Steel Pipe & Tube (Ra ≤8μm)
• Electro Polished EP Stainless Steel Pipe & Tube (Ra ≤25μm)
• Sanitary Stainless Steel Pipe & Tube
• Capilllary Stainless Steel Pipe & Tube
• Instrument Stainless Steel Pipe & Tube

Main characteristics of S32707

• Excellent resistance to pitting and crevice corrosion
• Excellent resistance to stress corrosion cracking (SCC) in chloride containing environments
• High resistance to general corrosion in acidic environments
• Excellent resistance to erosion corrosion
• Excellent corrosion fatigue properties
• Extremely high mechanical strength
• Physical properties that offer design advantages
• Good weldability

UNS S32707 Applications

>Marine engineering

>Furnaces&gas turbines

>Chemical processing plants

>Boiler & pressure vessels

>Nuclear power plants

Chemical composition

C	Si	Mn	S	P	Cr	Ni	Mo	Cu	N
max	max	max	max	max
0.03	1.00	1.50	0.02	0.035	26/29	5.5/9.5	4.0/5.0	1	0.3/0.5

Mechanical Properties

Property	Value
Tensile Strength, min, ksi, [MPa]	133 [920]
Yield Strength, min, ksi [MPa]	101 [700]
Elongation in 2 in. or 50mm, min, %	25
Hardness, max	HBW	HRC
	318	34

Stainless Steel Tube & Pipe Sizes:

Outsider Diameter OD : 6-630mm ; WT 3-60mm ; L max 16meter

Stainless Steel Tube Delivery Condition:

• Solution Treatment

Stainless Tube Surface:

Acid pickling – pre-passivation process of treating stainless steel parts with an acid solution, typically hydrochloric or sulfuric acid, which can remove oxide scale and heat tint while dissolving steel flecks embedded in the part.

Polishing – P grade sandpaper: P150, P200, P250, P300, P400, P500, P600, P700, P800

Stainless Pipe Inspection and Testing:

Chamical analysis / Tensile test at room temperature / flattening test / ring tensile test / drift expemdomg test / ring expanding test / leak tightness test / Tensile test at elevated temperature / impact test at room temperature / impact test at low temperature / eddy current test / ultrasonic test / magnetic flux leakage test

Stainless Tube Marking and Packages:

In addition to the marking prescribed in specification as client’s request.

Bare / Nylon / Plastic / Wooden Case

General corrosion

General corrosion can limit the service life of a stainless steel component in contact with a process solution. S32707 is highly resistant to corrosion by organic acids,e.g.formic acid and acetic acid.It also remains resistant in contaminated acid.The alloy is,therefore,a competitive alternative to high alloyed austenitic stainless steels and Ni-base alloys in applications where standard austenitic stainless steels corrode at a high rate.

Stress corrosion cracking

Stress corrosion cracking (SCC) is perhaps the most serious form of corrosion encountered in industrial processes as it can lead to rapid material failure.Standard austenitic grades can crack even at very low chloride levels.The risk of SCC can be eliminated with the use of more resistant

materials,such as high nickel alloys or duplex stainless steels.While the austenitic steels in many cases become resistant at Ni levels above 25%,the duplex alloys will have the same or higher resistance at much lower alloying levels,due to the dual phase structure .The SCC resistance of S32707 in chloride solutions at high temperatures is illustrated.An autoclave SCC test,where the samples are loaded to the yield strength R level,was conducted.The pressure was approximately 100 bar and the oxygen content 8 ppm.Fresh NaCl solution was pumped constantly into the chamber and duration of the test was 1000h (6 weeks).There were no signs of SCC up to 1000 ppm CI /300 C and 10000 ppm CI /250C.

Localized corrosion

In chloride containing waters under oxidizing conditions, pitting or crevice corrosion are perhaps the most common failure modes for stainless steels.Modern duplex stainless steels,such as 2507,were developed explicitly to have high resistance to pitting and crevice corrosion. All the experience gained from this grade has been utilized