Classifications

• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
  • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
  • C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D6/00—Heat treatment of ferrous alloys
  • C21D6/004—Heat treatment of ferrous alloys containing Cr and Ni
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
  • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
  • C22C38/46—Ferrous alloys, e.g. steel alloys containing chromium with nickel with vanadium

Definitions

• the invention relates to stainless steel materials with good corrosion resistance and mechanical properties.Specifically, it shows excellent corrosion resistance to both seawater and hydrogen sulfide, and mechanical properties such as strength and toughness. Further, the present invention relates to a stainless steel material having good structural characteristics.
• austenitic stainless steel was considered to use austenitic stainless steel.However, this stainless steel could withstand hydrogen chloride corrosion, but had problems in the presence of chlorides, for example, corrosion resistance on the sea floor. I know. Conventionally, Ti-based alloys and Ni-based alloys have been known as materials capable of withstanding such harsh environments, but these are extremely expensive and expensive. Economical materials must be provided. Also used for the above applications
• the material used must be able to withstand excessive water pressure and be used semi-permanently.Therefore, high strength to ensure a sufficient safety factor and high toughness to prevent sudden destruction It is necessary to have a cost of
• composition and heat It was found that good properties were exhibited depending on the processing conditions.
• AM355 CA ISI 6344 is known as a kind of semi-solid stainless steel. * It is said that the type of sale originally does not combine the outset hardening elements, the hardening is due to martensite transformation, and the subsequent age hardening is due to baking; For this reason, various recommended heat treatment methods, such as subzero cooling, aging, double aging, double transformation, low tempering after cold quenching, etc., have been performed, resulting in excellent mechanical properties (tensile strength). :
• the heat treatment conditions of the present invention are as follows:
• a solution treatment was performed by heating to 130 to 110 ° C.
• Nb has the effect of fixing C, which causes slow cooling embrittlement and grain boundary embrittlement.
• W1PO i? NATl It is indispensable to dissolve at a temperature of 130 or more. However, if it exceeds 110, crystal grains become coarse,
• Cooling rate 0.2 ° C / sec or more
• Quenching after consolidation and post-treatment is an unconditional condition to suppress Cr carbide pulverization to grain boundaries and obtain excellent corrosion resistance.
• the average cooling rate to the room must be 0.2 ° C / sec. That is, in general, water cooling is preferable, but at least a cooling rate of at least oil cooling is required, and furnace cooling or air cooling does not achieve the object of the invention.
• the present invention is constructed as described above, it is possible to economically produce stainless steel promotion materials having good corrosion resistance and mechanical strength, especially stainless steel materials having good structurability by simple heat treatment. It became possible to do.
• the U-shaped bending test piece was enclosed in an auto crepe together with air-saturated artificial seawater, heated to 100 ° C. and held for 700 hours. The presence or absence of cracking at this time was determined with a microscope (100 times magnification).
• the plate-shaped test piece was immersed for 2 weeks in artificial seawater at 50 in which hydrochloric acid was adjusted to 3.5. At this time, the presence or absence of pitting was determined by weight loss.
• the balance is Fe and inevitable impurities other than P and S i'2
• Nos. 9 to 11 are for heat treatment.
• No. 9 has low contents of Ni, M0 and V,
• No. 10 contains more Ni than No. 9
• the austenite stabilizing elements C and M11 and Mo are the austenite stabilizing elements C and M11 and Mo.
• the corrosion resistance is not improved as compared with No. 9 due to the small amount.
• No. 11 1 has N i, Cr and M n unnecessarily large, and conversely V and
• the invention is configured as described above, the addition amount of Ni is suppressed to the minimum, and it is not necessary to add an exceptionally high-grade alloying element. Therefore, the corrosion-resistant high-strength stainless steel material can be provided at a very low cost. Also this stearyl down Les scan ⁇ is 2 5 kg f / ao 2 or more 0 2% ⁇ Kaoyobi 1 0 kg f -. And is to be given a higher toughness values (VEO), consuming an excessive Kori ⁇ It is useful as a material for such seabed facilities or other parts with large loads, and its corrosion resistance is as follows: corrosion resistance to cracking, chloride cracking resistance, crevice corrosion resistance, and crevice corrosion resistance. Sulfur and chloride are present because they exhibit good properties, and they can be used safely even under severe corrosion conditions, and can be used under heavy loads such as deep oil fields and offshore oil fields. The best materials for equipment used in the environment were provided at low cost.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Crystallography & Structural Chemistry (AREA)
• Heat Treatment Of Steel (AREA)
• Heat Treatment Of Articles (AREA)

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• 1983
  • 1983-01-31 JP JP1500483A patent/JPS59140327A/ja active Granted
• 1984
  • 1984-01-28 WO PCT/JP1984/000023 patent/WO1984002929A1/ja not_active Ceased

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