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US3563729A - Free-machining corrosion-resistant stainless steel - Google Patents

Free-machining corrosion-resistant stainless steel Download PDF

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Publication number
US3563729A
US3563729A US721647A US3563729DA US3563729A US 3563729 A US3563729 A US 3563729A US 721647 A US721647 A US 721647A US 3563729D A US3563729D A US 3563729DA US 3563729 A US3563729 A US 3563729A
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machinability
sulfur
percent
stainless steel
corrosion
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US721647A
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Curtis W Kovach
Arthur Moskowitz
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Crucible Materials Corp
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Crucible Inc
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Assigned to CHASE MANHATTAN BANK, THE (NATIONAL ASSOCIATION) AS AGENT, MELLON BANK, N.A. FOR THE CHASE MANHATTAN BANK (NATIONAL ASSOCIATION) AND MELLON BANK N.A. reassignment CHASE MANHATTAN BANK, THE (NATIONAL ASSOCIATION) AS AGENT SECURITY INTEREST (SEE DOCUMENT FOR DETAILS). 1ST Assignors: CRUCIBLE MATERIALS CORPORATION, A CORP. OF DE.
Assigned to MELLON FINANCIAL SERVICES CORPORATION, MELLON BANK, N.A. AS AGENT FOR MELLON BANK N.A. & MELLON FINANCIAL SERVICES CORPORATION reassignment MELLON FINANCIAL SERVICES CORPORATION SECURITY INTEREST (SEE DOCUMENT FOR DETAILS). 2ND Assignors: CRUCIBLE MATERIALS CORPORATION, A CORP. OF DE.
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    • 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
    • C22C38/60—Ferrous alloys, e.g. steel alloys containing lead, selenium, tellurium, or antimony, or more than 0.04% by weight of sulfur
    • 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

Definitions

  • a more specific object of the invention is to promote the machinability of an austenitic stainless steel, without impairing corrosion resistance, by the inclusion of sulfur in an amount within the range of .04 to .07 percent, in the absence of significant additions of machinability promoting elements, such as aluminum, phosphorus and copper.
  • FIG. 1 is a graph showing the improvement in machinability achieved by the practice of the present invention, as demonstrated by data relating to drill machinability, tool life and lathe power;
  • FIG. 2 is a graph showing the effect of sulfur on the corrosion resistance of steel in accordance with the present invention in a 10 percent sulfuric acid solution at 170 F.;
  • FIG. 3 is a graph showing the effect of sulfur on the corrosion resistance of steel in accordance with the present invention in boiling glacial acetic acid.
  • FIG. 4 is a graph showing the effect of sulfur in stainless steel in accordance with the present invention on the pitting resistance of the steel in simulated seawater
  • composition of the austenitic stainless steel in accordance with the present invention is within the following limits:
  • Iron, percent phorus, that in combination with the sulfur will promote machinability.
  • elements such as copper, selenium, tellurium, bismuth, lead and silver have been used in combination with low sulfur contents to achieve the desired result.
  • the inclusion of these elements although effective at least to a degree for the purpose of improving machinability, has inherent disadvantages. For example, many of them will have a seriously detrimental effect on hot workability. If elements such as. phosphorus and aluminum are used in substantial amounts, the cleanliness of the steel will be adversely affected.
  • the inclusion of copper in an effective amount for the purpose of machinability which may typically be within the range of 1.5 to 5 percent, substantially increases the cost of the alloy. The same is true for selenium and many of the other elements it used in substantial amounts.
  • austenitic stainless steels within the above-stated composition limits are characterized by improved machinability and good corrosion resistance.
  • sulfur within the relatively low range of .04 to .07 percent, which range is critical for the purpose of the invention, an unexpected improvement in machinability is achieved in combination with corrosion resistance much better than that resulting if greater amounts of sulfur are used in accordance with conventional practice for producing free-machining steel.
  • conventional machinability-promoting elements such as phosphorus, copper and selenium, may be used in small or residual amounts without detrimentally affecting the steel, such are not required, as will be demonstrated hereinafter, to achieve the desired result of obtaining an austenitic stainless steel characterized by a combination of good machinability and corrosion resistance.
  • compositions listed in Table I were melted in a -pound air-induction furnace and cast into iron molds without aluminum deoxidation.
  • the critical effect of sulfur, in accordance with the present invention, was demonstrated by sulfur additions ranging in amounts from 0.007 to 0.32 percent sulfur. All ingots were forged to 1 75 inch bars at temperatures between 1800 to 2100 F. Portions of the bars were turned to one-inch diameter rounds for machinability testing, and the remainder was hot-rolled to 0.100-inch sheet for corrosion testing. All machinability and corrosion tests, as reported hereinafter, were conducted on material in the solution-annealed condition, obtained by soaking one hour at 1950 F. and then water quenching. The results of the machinability tests are reported in FIG. 1.
  • the drill-machinability tests were conducted by comparing all bars to a standard AISI Type 303 test bar.
  • the drill-machinability ratings were obtained by comparing the average drilling times for the test bars to the average drilling times for the standard Type 303 bar.
  • Lathe tool-life tests were conducted by determining the number of cuts until tool failure. For this purpose a A- inch wide M-2 cutoff tool, ground with seven degree toprake and front-clearance angles, three degrees side clearance, and no front-relief angle, was used.
  • the tests were conducted at a spindle speed of 600 r.p.m.
  • a feed rate of 0.002 i.p.r. and a sulfurized oil lubricant were used.
  • the lathe-power tests were conducted with a carbide tool that was used to make a standard plunge cut.
  • the criterion for machinability is the power required to make the cut as measured by a wattmeter on the lathe motor. Low power indicates good machinability.
  • the specimens for corrosion testing were prepared by belt grinding the hotrolled sheet to 0.080-inch thickness. Specimens 1 by 2 inches were then solution annealed and finished ground to 0.060 inch with dry No. 120 grit silicon carbide paper.
  • Corrosion tests as reported in FIG. 2, were conducted by placing specimens as described above in a 10percent sulfuric acid solution maintained at a temperature of 170 F. The samples were maintained in the acid solution for a four-hour period and an eight-hour period. Upon removal from the acid, samples were weighed to deter- .07 percent or less, significant increased weight loss is avoided.
  • FIG. 3 similarly shows the effect of sulfur on corrosion resistance in the presence of boiling glacial acetic acid.
  • the samples subjected to the acetic acid did not show significant weight loss as long as sulfur was maintained at .07 percent or less.
  • weight loss is drastically increased.
  • Tests were also conducted to determine the effect of sulfur on the pitting resistance of the austenitic stainless steel. These tests were conducted in a simulated seawater environment prepared in accordance with the Navy Department Specification 44T27b, July 1, 1940. The specimens were exposed for eigtheen days at a temperature of 86 F. The pitting frequency was evaluated by visual counting at a magnification of 15X. The results of this test are shown in FIG. 4. As may be seen from this figure, at sulfur contents of .04 to .07 percent, which is within the range of the present invention, the pitting is relatively low.
  • An austenitic stainless steel characterized by a combination of machinability and corrosion resistance consisting substantially of, in percent, carbon .25 max., manganese 3 max., phosphorus .06 max., silicon 3 max., nickel 6 to 22, chromium 16 to 26, molybdenum 4 max., copper 1 max., up to 2 of at least one element selected from the group consisting of columbium, titanium, tantalum and zirconium, nitrogen .25 max., sulfur .04 to .07, and the balance iron and incidental impurities.
  • An austenitic stainless steel characterized by a combination of machinability and corrosion resistance consisting essentially of, in percent, carbon .15 max., manganese 3 max., phosphorus .06 max., silicon 2 max., nickel 6 to 14, chromium 16 to 20, molybdenum 4 max, cooper 1 max, sulfur .04 to .07, and the balance iron and incidental impurities.
  • the steel of claim 2 further restricted by carbon .15 max., nickel 10 to 14, chromium 16 to 19 and molybdenum 1.5 to 4.
  • the steel of claim 2 further restricted by carbon .15 max., nickel 8 to 12, chromium 16 to 19 and molybdenum linax.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Heat Treatment Of Steel (AREA)
US721647A 1968-04-16 1968-04-16 Free-machining corrosion-resistant stainless steel Expired - Lifetime US3563729A (en)

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Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3772005A (en) * 1970-10-13 1973-11-13 Int Nickel Co Corrosion resistant ultra high strength stainless steel
US3837846A (en) * 1971-04-08 1974-09-24 Ver Deutsche Metallwerke Ag Austenitic steel alloy adapted to be welded without cracking
US3856516A (en) * 1970-02-12 1974-12-24 Blair Knox Co Low creep high strength ferrous alloy
JPS5284135A (en) * 1976-11-08 1977-07-13 Mitsubishi Heavy Ind Ltd Carburizinggresisting alloys
US4576641A (en) * 1982-09-02 1986-03-18 The United States Of America As Represented By The United States Department Of Energy Austenitic alloy and reactor components made thereof
EP0207697A1 (en) * 1985-06-26 1987-01-07 AlliedSignal Inc. Cast stainless steel alloy and method for its manufacture
EP0260792A2 (en) * 1986-09-19 1988-03-23 Crucible Materials Corporation Corrosion resistant austenitic stainless steel
US4959513A (en) * 1989-11-03 1990-09-25 Carpenter Technology Corporation Magnetically biased device incorporating a free machining, non-magnetic, austenitic stainless steel
WO1991006685A1 (en) * 1989-11-03 1991-05-16 Carpenter Technology Corporation A free machining, non-magnetic, austenitic stainless steel alloy and a magnetically biased device incorporating the same
US5154781A (en) * 1991-05-30 1992-10-13 Wilson Sporting Goods Co. Method to make casting alloy golf clubs
US5393487A (en) * 1993-08-17 1995-02-28 J & L Specialty Products Corporation Steel alloy having improved creep strength
US5512238A (en) * 1995-06-07 1996-04-30 Crs Holdings, Inc. Free-machining austenitic stainless steel
EP1312691A1 (fr) * 2001-11-16 2003-05-21 Usinor Alliage austénitique pour tenue à chaud à coulabilité et transformation améliorées, procédé de fabrication de billettes et de fils
WO2004005571A1 (de) * 2002-07-02 2004-01-15 Firth Ag Stahllegierung

Cited By (20)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3856516A (en) * 1970-02-12 1974-12-24 Blair Knox Co Low creep high strength ferrous alloy
US3772005A (en) * 1970-10-13 1973-11-13 Int Nickel Co Corrosion resistant ultra high strength stainless steel
US3837846A (en) * 1971-04-08 1974-09-24 Ver Deutsche Metallwerke Ag Austenitic steel alloy adapted to be welded without cracking
JPS5284135A (en) * 1976-11-08 1977-07-13 Mitsubishi Heavy Ind Ltd Carburizinggresisting alloys
JPS569260B2 (es) * 1976-11-08 1981-02-28
US4576641A (en) * 1982-09-02 1986-03-18 The United States Of America As Represented By The United States Department Of Energy Austenitic alloy and reactor components made thereof
EP0207697A1 (en) * 1985-06-26 1987-01-07 AlliedSignal Inc. Cast stainless steel alloy and method for its manufacture
EP0260792A2 (en) * 1986-09-19 1988-03-23 Crucible Materials Corporation Corrosion resistant austenitic stainless steel
EP0260792A3 (en) * 1986-09-19 1989-02-15 Crucible Materials Corporation Corrosion resistant austenitic stainless steel
WO1991006685A1 (en) * 1989-11-03 1991-05-16 Carpenter Technology Corporation A free machining, non-magnetic, austenitic stainless steel alloy and a magnetically biased device incorporating the same
US4959513A (en) * 1989-11-03 1990-09-25 Carpenter Technology Corporation Magnetically biased device incorporating a free machining, non-magnetic, austenitic stainless steel
US5087414A (en) * 1989-11-03 1992-02-11 Carpenter Technology Corporation Free machining, mon-magnetic, stainless steel alloy
JPH05500833A (ja) * 1989-11-03 1993-02-18 シーアールエス　ホールディングス，インコーポレイテッド 快削性・非磁性オーステナイト系ステンレス鋼合金及び同合金を取り入れた磁気偏向装置
JP2788928B2 (ja) 1989-11-03 1998-08-20 シーアールエス ホールディングス，インコーポレイテッド 快削性・非磁性オーステナイト系ステンレス鋼合金及び同合金を取り入れた磁気偏向装置
US5154781A (en) * 1991-05-30 1992-10-13 Wilson Sporting Goods Co. Method to make casting alloy golf clubs
US5393487A (en) * 1993-08-17 1995-02-28 J & L Specialty Products Corporation Steel alloy having improved creep strength
US5512238A (en) * 1995-06-07 1996-04-30 Crs Holdings, Inc. Free-machining austenitic stainless steel
WO1996041032A1 (en) * 1995-06-07 1996-12-19 Crs Holdings, Inc. Free-machining austenitic stainless steel
EP1312691A1 (fr) * 2001-11-16 2003-05-21 Usinor Alliage austénitique pour tenue à chaud à coulabilité et transformation améliorées, procédé de fabrication de billettes et de fils
WO2004005571A1 (de) * 2002-07-02 2004-01-15 Firth Ag Stahllegierung

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ES360825A1 (es) 1970-10-16

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