Corrosion resistant steel structural member

• US 4,919,885 A
• Filed: 09/28/1988
• Issued: 04/24/1990
• Est. Priority Date: 08/14/1986
• Status: Expired due to Fees

• Current Assignee: Thyssen Stahl AG
• Original Assignee: Thyssen Stahl AG
• Inventors: Robusch, Gunter, Hachtel, Ludwig, Meyer, Lutz
• Primary Examiner(s): Yee, Deborah
• Application Number:
  US07/252,006
• Time in Patent Office: 573 Days
• Field of Search: 148/333, 420/104, 420/112, 420/126
• US Class Current: 420/104
• CPC Class Codes: C22C 38/28 with titanium or zirconium

Abstract

The invention relates to a structural steel having high resistance to intergranular stress operation cracking, more particularly in nitrate solutions and good welding properties (in % by mass):

0.01 to 0.04% carbon

up to 0.012% nitrogen

0.08 to 0.22% titanium with Ti equal or greater than 3.5 (C+N)

0.2 to 2.5% manganese

2.0 to 5.5% chromium

0.01 to 0.10% aluminium

up to 0.5% silicon

up to 1.0% nickel

up to 0.02% phosphorus

up to 0.02% sulphur

the residue being iron and unavoidable impurities.

Claims

1. In a structural member of hot blast stoves, heat exchangers, furnaces, boilers, tanks, vessels and pipes exposed to intergranular stress corrosion cracking in nitrate-containing solutions, constructed of a weldable structural steel, wherein the improvement comprises that the structural steel having high resistance to intergranular stress corrosion cracking in nitrate-containing solutions and good weldability, consists essentially in % by mass, of

3. A structural member according to claim 1, wherein the structural steel consists essentially, in % by mass, of

0.01 to 0.02 % carbon

up to 0.005 % nitrogen

0.08 to 0.15 % titanium with Ti equal or greater than 3.5 (carbon + nitrogen)

0.2 to 2.0 % manganese

2.5 to 5.5 % chromium

0.01 to 0.1 % aluminium

up to 0.5 % silicon

up to 0.01 % phosphorus

up to 0.01 % sulphur,

the residues being iron and unavoidable impurities.

4. A structural member according to claim 1, constructed of a weldable structural steel having the composition set forth in claim 1, which has good resistance to intergranular stress corrosion cracking in nitrate-containing solutions and good weldability, even without thermal pretreatment and postreatment.

6. A structural member according to claim 1, constructed of a weldable structural steel having the composition set forth in claim 7 which, with simultaneous and corrosive stressing, has a service life of more than 2,400 hours under a stress corrosion cracking test in a boiling solution containing 100 g nitrate per liter under a constant load of 1.4 R_p 0.2, and a reduction of area upon rupture of more than 40% after a stress corrosion cracking test in a solution at 95°

C. containing 10 g nitrate per liter with a constant strain rate.

7. A structural member according to claim 3, constructed of a weldable structural steel having the composition set forth in claim 8 which, with simultaneous and corrosive stressing, has a service life of more than 2,400 hours under a stress corrosion cracking test in a boiling solution containing 100 g nitrate per liter under a constant load of 1.4 R_p 0.2, and a reduction of area upon rupture of more than 40% after a stress corrosion cracking test in a solution at 95°

C. containing 10 g nitrate per liter with a constant strain rate.

2. 01 to 0.04 % carbon

up to 0.012 % nitrogen

0.08 to 0.22 % titanium with Ti equal or greater than 3.5 (carbon + nitrogen)

0.2 to 2.5 % manganese

2.0 to 5.5 % chromium

0.01 to 0.10 % aluminium

up to 0.5 % silicon

up to 1.0 % nickel

up to 0.02 % phosphorus

up to 0.02 % sulphur,

the residue being iron and unavoidable impurities.

5. A structural member according to claim 2, constructed of a weldable structural steel having the composition set forth in claim 8, which has good resistance to intergranular stress corrosion cracking in nitrate-containing solutions and good weldability, even without thermal pretreatment and postreatment.