US3645726A - Resistance to stress-corrosion cracking in nickel alloys - Google Patents

Resistance to stress-corrosion cracking in nickel alloys Download PDF

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US3645726A
US3645726A US459050A US3645726DA US3645726A US 3645726 A US3645726 A US 3645726A US 459050 A US459050 A US 459050A US 3645726D A US3645726D A US 3645726DA US 3645726 A US3645726 A US 3645726A
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percent
alloy
alloys
amount
nickel
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US459050A
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Harry R Copson
Sheldon W Dean Jr
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Huntington Alloys Corp
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International Nickel Co Inc
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H51/00—Electromagnetic relays
    • H01H51/02—Non-polarised relays
    • H01H51/04—Non-polarised relays with single armature; with single set of ganged armatures
    • H01H51/06—Armature is movable between two limit positions of rest and is moved in one direction due to energisation of an electromagnet and after the electromagnet is de-energised is returned by energy stored during the movement in the first direction, e.g. by using a spring, by using a permanent magnet, by gravity
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C19/00—Alloys based on nickel or cobalt
    • C22C19/03—Alloys based on nickel or cobalt based on nickel
    • C22C19/05—Alloys based on nickel or cobalt based on nickel with chromium
    • C22C19/058—Alloys based on nickel or cobalt based on nickel with chromium without Mo and W
    • 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
    • C22C38/50—Ferrous alloys, e.g. steel alloys containing chromium with nickel with titanium or zirconium

Definitions

  • the present invention relates to nickel-chromium and nickel-chromium-iron base alloys and, more particularly, to minimizing and/or overcoming the vexatious problem of stress-corrosion cracking of such alloys when exposed to a high-purity water environment.
  • stress-corrosion cracking per se is a well known phenomenon.
  • a wealth of literature coping with the problem of stress-corrosion cracking of the austenitic nickelchromium stainless steels has been accumulated, particularly with regard to chloride environments. While known recent avenues of approach for stainless steel were considered in seeking a solution to the problem herein, it was deemed that little by way of substantive merit would be expected, since what is apparently applicable to the stainless steels is not seemingly apposite to the instant situation.
  • Stress-corrosion cracking of the stainless steels in chloride solutions is primarily transgranular in nature whereas the subject type of stresscorrosion cracking in nickel-chromium-iron alloys is intergranular.
  • high-purity water as contemplated herein contains not much above a total solids content of less than one part per million (ppm) by weight and which has been distilled and/or deionized or otherwise treated such that it will manifest a specific resistance of about 500,000 ohm-cm. or higher. As is appreciated by those skilled in the art, this type of water is used in atomic power equipment including nuclear pressure vessels.
  • Certain environmental conditions have been established which either promote or are causative of inducing or creating a propensity for detrimental intergranular stress-corrosion cracking to occur in nickel-chromium-iron alloys.
  • Aerated high-purity water in combination with the surface condition of the alloys) is one such condition and temperature is another.
  • high-purity water is devoid of oxygen and it is believed that the usual absence thereof has been responsible, to a considerable degree, for the lack of intergranular stress-corrosion cracking of nickel-chromium and nickelchromium-iron alloys heretofore on a commercial scale. But the possibilities of oxygen contamination are indeed more than sufficient to warrant the necessity of finding alloys which afford a markedly higher degree of resistance to such attack.
  • crevices in combination with aerated, high-temperature, high-purity water exert a most pronounced subversive influence in producing stresscorrosion cracking and other forms of corrosion. Whether the crevice by nature be a flaw, crack, sharp indentation or other such surface defect is rather inconsequential. The unfortunate fact remains that it is exceedingly difficult, if not impossible, to avoid or prevent the occurrence thereof. If the alloy is incapable of resisting stress-corrosion attack, there is also at least the likelihood of greater crevice buildup of corroded product.
  • nickelchromium and nickel-chromium-iron base alloys of special composition which manifest a high overall resistance to stresscorrosion cracking when such alloys are in contact with aerated high-purity water at a temperature above about 300 F and up to at least about 660 F.
  • stress-corrosion cracking of nickel-chromium and nickel-chromium-iron alloys to be brought into contact with aerated high-purity water, the temperature of the water being from above about 300 to about 660 F., e.g., 450 F.
  • alloys of the following most advantageous composition can be greatly minimized by utilizing alloys of the following most advantageous composition (based on weight percent): about 14 to about 25 percent chromium, up to about percent iron, e.g., l to 8 percent iron, aluminum in an amount up to 0.05 percent, e.g., about 0.005 to 0.05 percent aluminum, titanium in an amount up to 0.1 percent, e.g., about 0.01 to 0.1 percent titanium, silicon in an amount up to 0.25 percent, e.g., about 0.01 to 0.25 percent silicon, carbon in an amount up to 0.1 percent, e.g., 0.01 to 0.1 percent carbon, and the balance essentially nickel.
  • the grain size and hardness of the alloys are advantageous to control since relatively soft, fine-grained alloys tend to manifest greater resistance to stress-corrosion cracking.
  • a desired correlation between grain size and hardness is generally reflected by the shaded area to the left of and/or below curves AB and CD of the attached drawing, i.e., the hardness and grain size of the alloys are preferably interrelated such that they represent a point lying within the aforesaid areas of the drawing.
  • Hardness and grain size while dependent on the specific chemistry of the alloys, are also affected by heat treatment.
  • High-temperature annealing treatments with or without the application of cold rolling are conducive to coarse-grained structures, particularly where the alloys are thereafter subjected to a sensitizing treatment.
  • alloys contemplated herein would often be welded to form a welded structure.
  • the alloys would pass through a sensitizing temperature range of below about 1,500" to 800 F., e.g., 1,450t0 850 F.
  • the same alloy might manifest good resistance to intergranular stresscorrosion cracking when in the annealed condition, it might very well show cracking in the sensitized condition.
  • a most satisfactory treatment in achieving a fine grain size is to cold roll the alloys up to 50 percent reduction in thickness, e.g., 25 to 40 percent, and thereafter anneal at 1,550 to l,650 F.
  • This treatment provides a grain on the order of about ASTM grain size No. 9 or smaller and is further beneficial in that higher amounts of carbon can be employed, if desired, than otherwise might be the case.
  • Cold rolling is advantageous since it results in attaining an elongated grain structure and this type of grain is deemed more resistant to intergranular attack.
  • the best condition is a soft, elongated and fine-grained, low-carbon alloy.
  • the limiting amounts of carbon present is influenced by grain size and heat treatment. It is deemed, however, that a basic criterion as to carbon content is in respect of the amount of carbon or carbide segregated at the grain boundaries in approximate inverse relation to the grain boundary area. Thus, where there is a fair number of carbides at a given grain boundary area of, say, X, cracking might occur, whereas if the grain boundary area was 2X" or 3X, the susceptibility to cracking would be greatly lessened. With proper processing (cold rolling) and heat treatment to achieve a fine grain size of about ASTM 7 or smaller, up to 0.15 percent carbon can be employed. However, it is advantageous to maintain the carbon content at a level not greater than about 0.1 percent and preferably not greater than 0.03 percent to thereby minimize the occurrence of large amounts of carbon and/or carbide at a small grain boundary area.
  • alloys of the following composition about 14 to about 30 percent chromium, up to about 50 percent iron, preferably not more than 25' percent iron, about 0.003 to about 0.05 percent aluminum. about 0.005 to about 0.15 percent titanium, about 0.01 to about 0.3 percent silicon, about 0.01 to about 0.15 percent carbon, and the balance essentially nickel, the nickel constituting at least 30 percent and preferably at least 35 percent of the alloys.
  • alloy test specimens were prepared having compositions given in Table 1 (Alloys A to M being outside the invention and Alloys 1 to 7 being within the invention).
  • alloys were prepared using vacuum melting techniques and using materials of relatively high purity.
  • the alloys were cast as -pound ingots. After removing surface defects, the alloys were heated to 2,200 F. and forged to flats (1 inch by 3.5 inches by 10 inches). After reheating to 2,150 F., the flats were hot rolled to a thickness of about 0.2 inch. Subsequent to conventional processing, including cold rolling to provide specimens about 0.12 inch thick, the alloys were subjected to heat treatment. Two different heat treatments were employed, one consisting of solution treating at about 1,950 F. for onequarter hour followed by a water quench. A high-solution treatment temperature was deliberately employed to add to the severity of the test.
  • the second treatment consisted of a sensitizing treatment whereby the specimen was heated to a temperature of about 1,300 F., held at this temperature for about one hour and then air cooled.
  • a sensitizing treatment whereby the specimen was heated to a temperature of about 1,300 F., held at this temperature for about one hour and then air cooled.
  • two specimens (strips) of each alloy composition were prepared, one being subjected to the solution anneal treatment, the other being subjected to the sensitizing treatment. It was deemed necessary to test the alloys using the sensitizing heat treatment since, as referred to above herein, the alloys would be often used in this condition.
  • test solution was aerated high-purity water (air saturated at one atmosphere) with the pH thereof having been adjusted to about pH 10.0.
  • This test solution was placed in the autoclave and a head space having additional air was maintained.
  • the test specimens were immersed in the solution and the autoclave sealed and brought to a test temperature of about 600 to 660 F.
  • the autoclaves were opened about every 2 weeks and the specimens inspected for cracks, whereafter the tests were restarted with fresh solution in those instances where cracking was not visually observed.
  • the tests were conducted generally over a period of 8 weeks and both visual and metallographic examinations of the specimens were made.
  • Alloys A, D and L additionally illustrate that aluminum, titanium and silicon in amounts as low as 0.07 percent, 0.17 percent and 0.44 percent, respectively, notwithstanding that the relationship between hardness and grain size might be represented by a point within shaded areas of curves AB and/or CD of the drawing, are conducive to cracking. Alloys E, G and J followed a rather similar pattern. Alloy M indicates that when the hardness, grain size relationship defined by curves AB and/or CD is not satisfied, cracking can ensue although the chemistry of the alloy might be within the compositional ranges described herein. However, Alloy M' responded relatively well and with a lower carbon content (Alloys 1 to 7) it is considered that greater resistance to stresscorrosion cracking would be conferred. A review of all the data concerning Alloys A through M reflects that when the alloys are in the sensitized condition, there is a greater susceptibility to premature cracking. This is, of course, also indicated by the curves AB and CD.
  • Alloys Nos. 1 through 7 performed satisfactorily under the same test conditions.
  • the composition of Alloys Nos. 1 through 7 is within the scope contemplated herein as is also the preferred relationship between hardness and grain size.
  • the present invention provides nickel-chromium and nickel-chromium-iron alloys highly resistant to intergranular stress-corrosion cracking when in contact with pressurized, aerated water at a temperature of above about 300 to about 660 F., notwithstanding that the surface of the alloys be characterized by a crevice or some such similar surface defect.
  • the invention is also applicable in minimizing intergranular stress-corrosion cracking in aerated high-purity water at surface areas which do not contain obvio us crevices yressure vessels, heat exchangers, steam genera- Table Annealed Sensitized Cracking time Cracking time Gram Metallo- Grain Metallo- VHN** size Visual graphic VHN size Visual graphic Am.
  • OK C OK 137 3.5 OK, OK C*, OK 13. 141 6.5 8. OK C, OK 145 6 OK, OK OK, OK C. 148 5 4. OK C, OK 200 4 OK C D. 142 5.5 OK, OK C", OK 147 5 OK, OK OK, OK E. 151 5.5 OK, OK OK, OK 148 4 4 C, C F. 139 4.5 8, OK C, OK 141 4.5 4, OK C, OK G. 154 4 OK, OK OK, OK 148 5.5 4, OK C, OK H. 223 9.5 OK, OK OK, OK 207 9.5 8, OK C, OK 1.
  • OK C 225 9 OK, OK C, OK 260 9 4, OK C .1 176 7 OK, OK C, OK 271 6.5 4, OK C, OK K. 236 9 OK, OK OK, OK 313 8 6, OK C, OK L. 149 5 OK, OK C, OK 140 5 OK, OK OK, OK M 155 5 OK, OK OK, OK 154 6 8, OK C, OK 1. 156 6.5 OK, OK OK, OK 138 5.5 OK, OK OK, OK 2 136 5 OK, OK OK, OK 136 5 OK, OK OK. OK
  • C Cracks extended more than L, through specimen.
  • C* Shallow cracks usually about 1 to 2 grains deep.
  • tion surfaces, tubing, etc. are illustrative of the of articles which can be fabricated from the alloys of the invention.
  • the present invention should not be confused with nickel-chromium and nickel-chromium-iron alloys of the agehardening type and which contain substantial amounts of precipitation hardening ingredients such as aluminum and titanium.
  • the alloys of the present invention are, as a practical matter, of the nonage hardening type.
  • annealed condition means the condition of the alloy upon cooling from the solution annealed condition (often referred to as simply the annealed condition).
  • sensitized condition refers to the condition of the alloy after cooling from a sensitizing treatment.
  • a nickel-chromium base alloy characterized by an improved level of resistance to intergranular stress-corrosion cracking when subjected to contact with aerated high-purity water at a temperature of about 300 to about 660 F said alloy consisting of about 14 to percent chromium, up to 10 percent iron, aluminum present in an amount up to 0.05 percent, titanium present in an amount up to 0.1 percent, silicon present in an amount up to 0.3 percent, carbon in an amount up to 0.1 percent and the balance essentially nickel.
  • a process for providing a nickel-chromium base alloy characterized by good resistance to intergranular stress-corrosion attack when in contact with aerated high-purity water at a temperature of about 300 to about 660 F. which comprises establishing a molten bath containing chromium, iron, aluminum, titanium, silicon, carbon and the balance essentially nickel, controlling the amounts of the respective constituents within the following ranges: about 14 to 25 percent chromium, up to 10 percent iron, aluminum present in an amount up to 0.05 percent, titanium present in an amount up to 0.1 percent, silicon present in an amount up to 0.25 percent, carbon in an amount up to 0.03 percent, and the balance essentially nickel, v

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  • Chemical & Material Sciences (AREA)
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  • Electromagnetism (AREA)
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US459050A 1965-05-26 1965-05-26 Resistance to stress-corrosion cracking in nickel alloys Expired - Lifetime US3645726A (en)

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AT (1) AT271917B (enrdf_load_html_response)
BE (1) BE681642A (enrdf_load_html_response)
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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4004080A (en) * 1975-07-25 1977-01-18 Rca Corporation Metal coating for video discs
US4481043A (en) * 1982-12-07 1984-11-06 The United States Of America As Represented By The United States Department Of Energy Heat treatment of NiCrFe alloy to optimize resistance to intergrannular stress corrosion
US4490186A (en) * 1982-11-10 1984-12-25 United Technologies Corporation Thermal-mechanical working of wrought non-hardenable nickel alloy
US4591393A (en) * 1977-02-10 1986-05-27 Exxon Production Research Co. Alloys having improved resistance to hydrogen embrittlement

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2596066B1 (fr) * 1986-03-18 1994-04-08 Electricite De France Alliage austenitique nickel-chrome-fer
AT391484B (de) * 1986-09-08 1990-10-10 Boehler Gmbh Hochwarmfeste, austenitische legierung und verfahren zu ihrer herstellung

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1542232A (en) * 1920-12-09 1925-06-16 Commentry Fourchambault & Deca Alloy

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1542232A (en) * 1920-12-09 1925-06-16 Commentry Fourchambault & Deca Alloy

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4004080A (en) * 1975-07-25 1977-01-18 Rca Corporation Metal coating for video discs
US4591393A (en) * 1977-02-10 1986-05-27 Exxon Production Research Co. Alloys having improved resistance to hydrogen embrittlement
US4490186A (en) * 1982-11-10 1984-12-25 United Technologies Corporation Thermal-mechanical working of wrought non-hardenable nickel alloy
US4481043A (en) * 1982-12-07 1984-11-06 The United States Of America As Represented By The United States Department Of Energy Heat treatment of NiCrFe alloy to optimize resistance to intergrannular stress corrosion

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NL6607289A (enrdf_load_html_response) 1966-11-28
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AT271917B (de) 1969-06-25
GB1071449A (en) 1967-06-07
SE336680B (enrdf_load_html_response) 1971-07-12
FR1556954A (enrdf_load_html_response) 1969-02-14
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ES327143A1 (es) 1967-11-01

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