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
  • C22C38/58—Ferrous alloys, e.g. steel alloys containing chromium with nickel with more than 1.5% by weight of manganese
• • 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
  • C22C38/001—Ferrous alloys, e.g. steel alloys containing N
• • 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
  • C22C38/42—Ferrous alloys, e.g. steel alloys containing chromium with nickel with copper

Definitions

• One of the objects of my invention is the provision of a stainless steel which is comparatively inexpensive in that it employes a minimum of expensive alloying ingredients; which steel readily lends itself to hot-working and then to cold-working at minimum cost in that it possesses a low work-hardening rate and permits maximum coldreduction without necessity for intermediate anneal; and which cold-worked steel readily lends itself to a variety of forming and fabricating operations.
• Another object is the provision of hot-rolled sheet, strip, wire and like products as well as the provision of cold-rolled sheet and strip of cold-drawn wire and the like, all at minimum cold-working costs; which coldrolled sheet, strip, wire and like products, as well as hotrolled products where desired, lend themselves to a variety of forming and fabricating operations such as bending, drawing, deep-drawing, spinning, and the like, as well as shearing, cutting, sawing and drilling; and which products readily may be brazed and welded as in the fabrication of a host of articles of ultimate use.
• a further object is the provision of a variety of stainless steel articles of ultimate indoor use such as kitchen sinks, trim fittings, and the like, having eye appeal yet being adapted to withstand the corrosive action of foodstutfs commonly encountered in kitchen, bath and other home and industrial usage, as Well as the provision of a variety of articles of outdoor use, notably automobile trim, wheel covers, bumpers and like bright metal arts appealing to the eye, yet functional, and well adapted to withstand the conditions encountered in actual practical use such as the dust and heat of summer, the cold of winter and the snow, sleet, ice and salt thrown up from the road in winter driving, as well as the salt atmosphere of the seashore, all without objectionable pitting, corrosion, rusting and discoloration.
• the type 301 grade of stainless steel (analyzing carbon 0.15% max., manganese 2.00% max, silicon 1.00% max., phosphorus .045 max., sulphur .03% max., chromium 16.00% to 18.00%, nickel 6.00% to 8.00%, and remainder iron) has been rather well received in the art for a variety of applications. The same may be said for the type 302 (analyzing carbon 0.15% max., manganese 2.00% max., silicon 1.00% max., phosphorus .045% max., sulphur .03% max., chromium 17.00% to 19.00%, nickel 8.00% to 10.00%, and remainder iron).
• Cold-rolled sheet and strip of the type 301 steel in annealed condition has a tensile strength of about 110,000 p.s.i., a yield strength of about 40,000 p.s.i., a 2" elongation of about 60%, with a hardness of about Rockwell B85.
• the type 302 cold-rolled and annealed sheet and strip has a tensile strength of about 90,000 p.s.i., a yield strength of about 40,000 p.s.i., a 2" elongation of about 50%, and a hardness of about Rockwell B85.
• a further known steel is the chromium-nickel-copper steel as described, for example, in the Bloom-Clarke U.S. Letters Patent 2,687,955 of August 31, 1954, entitled, Cold-Workable Stainless Steel and Articles. While that steel possesses a comparatively low work-hardening rate it, too, is comparatively expensive. And, moreover, at the higher nickel levels, when subjected to drastic deformation, as in severe deep-drawing in a single operation, the steel is inclined to local stressing and resultant irregularity in section.
• one of the principal objects of the present invention is the provision of a stainless steel of desired corrosion-resisting characteristics which employs a minimum of expensive alloying ingredients in its composition; which handles well in the furnace and teeming ladle; which works down from ingot to billet to sheet, strip, wire and the like, with ease; and which then readily lends itself to cold-reduction up to some to without necessity for intermediate anneal as in the production of cold-rolled sheet, strip and cold-drawn wire; which sheet, strip and wire are ductile and readily formable by a variety of forming operations.
• I provide a stainless steel which possesses the corrosion-resisting characteristics of the types 301 and 302 steels at substantially lower cost of converted products, that is, hot-rolled sheet, strip, wire and the like, as
• the steel of my invention essentially consists of carbon up to .15 preferably in the amount of about .04% to .15 manganese in the amount of .40% to 2.00%, silicon in the amount of .l5% to 1.0%, chromium in the amount of 16.0% to 19.0%, nickel in the amount of 5.5% to 8.0%, copper in the amount of .5% to 3.5%, nitrogen residual and remainder essentially iron.
• the steel of my invention is in every sense critical in its composition for I find that with any substantial change in the balance of the ingredients of the composition one or more of the desired properties are lost.
• the carbon content of my steel I find that the .15% figure approaches the limit of solubility for normal annealing and cooling rates.
• a carbon content exceeding .15% is inclined to give a sensitized structure with risk of a severe loss of corrosion resistance.
• the carbon content preferably, however, is maintained at a value not exceeding .08% in order to assure a minimum of work-hardening and especially a value of .04% to .08% since at least .04% carbon is desired for its stabilizing effect.
• a preferred range is .05 to 08%.
• the manganese content of my steel similarly is critical in that I find a manganese content exceeding 2.00% gives little benefit and increases the cost as well.
• the manganese content therefore, amounts to .4% to 2.00%, or even about .5 to 2.00%, and more particularly about 1.25% to 1.75%.
• the silicon content of my steel is critical; at least .15 is necessary to assure an ease of furnacing and teeming, while silicon exceeding 1.00% is objectionable because of its ferrite-forming tendencies. An excess of silicon requires additional nickel at, of course, additional expense, to compensate for the same. I therefore employ a silicon content of .15 to 1.00%, this preferably amounting to about .40% to .75
• the chromium content amounts to 16.0% to 19.0%, this being critical, too. Preferably, this ranges from 16.0% to 18.0%.
• a chromium content lower than 16.0% results in a loss of corrosion-resistance and, moreover, it is inclined to result in an objectionable increase in the work-hardening rate of the metal.
• Achromium content in excess of 19.0% is not acceptable because it results in an excessive deltaferrite content at ingot-rolling temperatures. Desired results are had with a chromium content of 17.25% to A nickel content of 5.5 to 8.0% is required in my steel, this preferably amounting to about 6.0% to 8.0%.
• Copper is an ingredient essential to the steel of my invention. This is employed in the amount of .5% to 3.5%. Actually, I employ a copper content of about 1.0% to 3.5%, more preferably about 1.0% to 3.0%. A copper content short of the 1.0% figure and certainly anything short of the .5 figure does not elfectively lower the work-hardening rate of the metal. And a copper content exceeding 3.0%, and certainly one exceeding 3.5%, is likely to result in hot-rolling difficulties, notably the likelihood of the metal to break in the hot-mill, since 3.5% is about the limit of solubility. Moreover, I feel that with an excess of copper, the corrosion resistance of the steel is inclined to suifer. The preferred copper range is 1.75% to 2.25%.
• the hot-rolled metal comes 011 the mill in coils which may be annealed and pickled, or merely pickled and then cold-worked to specification.
• Cold-rolled sheet and strip is had through a short routing through the mill, that is, without necessity for intermediate anneal.
• the amount of cold-reduction commonly approaches
• the hot-rolled wire is cold-drawn.
• the drawing operation is simply and inexpensively effected without necessity for intermediate anneal, the amount of cold-reduction being up to about 75%.
• My steel may be viewed as essentially consisting of carbon up to about .l5%, manganese .5% to 2.00%, silicon, .15% to 1.00%, chromium 16.0% to 19.0%, the chromium preferably being 16.0% to 18.0%, nickel 6.5% to 7.9%, copper 1.5% to 2.9%, more especially 1.9% to 2.9%, with nitrogen preferably in residual amounts only, and remainder essentially iron.
• such modified steel may be considered as essentially consisting of carbon about .05 to .15 manganese about 1.25 to 1.75 silicon about .40% to .75 chromium 16.0% to 18.0%, nickel about 7.0% to 7.9%, copper about 2.5% to 2.9%, and the remainder essentially iron.
• the low nitrogen steel of Heat 3611-1 may be compared with the high nitrogen steel of the heat M3 of my companion application (057% carbon, 1.64% manganese, .50% silicon, 17.61% chromium, 7.00% nickel, 1.98% copper, 030% nitrogen, remainder iron, for the Heat 3611-1, and 064% carbon, 1.49% manganese, .43% silicon, 17.74% chromium, 6.47% nickel, 1.93% copper, 060% nitrogen, and remainder iron, for the Heat M3).
• These two steel are of about the same carbon, manganese, chromium, nickel and copper contents.
• the steel of Heat 3612-1 of low nitrogen content (055% carbon, 1.55% manganese, .42% silicon, 17.63% chromium, 6.96% nickel, 2.49% copper, 031% nitrogen, and remainder iron) when coldreduced 75% (73.8% cold-reduction) has a .2% yield strength of 171.9K s.i. and a tensile strength of 195.6K s.i. as against a .2% yield strength of 173.5K s.i.
• the lower initial tensile strength of my present copperbearing steel makes for easier working, as also does the lower work-hardening rate (108.2K s.i. increase with 75 cold-reduction for Heat 3611-1 as against 1223K s.i. increase for Heat D1). Both factors are in favor of the copper-bearing steel of low nitrogen content.
• I provide in my invention a stainless steel of good corrosion-resisting characteristics, employing a minimum of expensive alloying ingredients.
• the steel is economically melted in the electric arc furnace. It furnaces well and teems well.
• the steel of my invention may be cold-worked, as by cold-rolling or cold-drawing, to a reduction in area amounting to about 75 or more without requiring an in termediate annealing operation.
• the production of coldrolled sheet and strip, and cold-drawn wire from hotrolled sheet, strip and wire thus is achieved at minimum expense.
• the steel and sheet, strip, wire and the like of my invention conveniently is supplied the trade in an annealed and pickled or in a bright annealed condition at significantly lower cost.
• These mill products well lend themselves to fabrication, as by bending, drawing, deep-drawing and other forming operations commonly practiced on the well known 18-8 chromium-nickel grade of stainless steel.
• these products may be sheared, cut, sawed, drilled and the like, as well as brazed and welded, as in the production of a variety of articles of ultimate use such as automobile body trim, window frames, door frames, wheel covers, bumpers, and the like, where bright metal and appeal to the eye is desired.
• the steel and articles well resist the attack of the salty atmosphere encountered at the seashore as well as the salt thrown up from the streets, roads and highways during the winter when salt commonly is employed to effect de-icing. And the steel of my invention is well adapted to withstand the abuse commonly encountered in every-day automobile driving and parking.
• Stainless steel essentially consisting of carbon up to about .15%, manganese .5% to 2.00%, silicon .15% to 1.00%, chromium 16.0% to 19.0%, nickel 6.5% to 7.9%, copper 1.5% to 2.9%, residual nitrogen, and remainder essentially iron.
• Stainless steel essentially consisting of carbon about .05% to .15%, manganese about 1.25% to 1.75%, silicon 7 about .15% to 1.00% silicon, about 16.0% to 19.0% chromium, about 6.5% to 7.9% nickel, about 1.5% to 2.9% copper, residual nitrogen, and remainder essentially iron.
• Stainless steel having good bend characteristics essentially consisting of carbon up to about .15 manganese .5 to 2.00%, sulphur not exceeding 006%, silicon .15 to 1.00%, chromium 16.0% to 19.0%, nickel 6.5% to 7.9%, copper 1.5% to 2.9%, nitrogen up to .O3%, and remainder essentially iron.
• Hot-rolled chromium-nickel-co-pper stainless steel sheet, strip, wire and the like essentially consisting of carbon up to about .15%, manganese .5% to 2.00%, silicon .15% to 1.00%, chromium 16.0% to 19.0%, nickel 6.5% to 7.9%, copper 1.5% to 2.9%, nitrogen up to .03 and remainderessentially iron.

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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 Strip Materials And Filament Materials (AREA)
• Heat Treatment Of Sheet Steel (AREA)

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Citations (5)

• 1965
  • 1965-02-01 US US429656A patent/US3282686A/en not_active Expired - Lifetime
• 1966
  • 1966-01-25 GB GB3278/66A patent/GB1097244A/en not_active Expired
  • 1966-01-28 BE BE675729D patent/BE675729A/xx unknown

Patent Citations (5)

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