US3288611A - Martensitic steel - Google Patents

Martensitic steel Download PDF

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Publication number
US3288611A
US3288611A US316116A US31611663A US3288611A US 3288611 A US3288611 A US 3288611A US 316116 A US316116 A US 316116A US 31611663 A US31611663 A US 31611663A US 3288611 A US3288611 A US 3288611A
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United States
Prior art keywords
steel
carbon
present
titanium
traces
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US316116A
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English (en)
Inventor
Remus A Lula
Iii Harry E Mccune
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Allegheny Ludlum Steel Corp
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Allegheny Ludlum Steel Corp
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Publication date
Application filed by Allegheny Ludlum Steel Corp filed Critical Allegheny Ludlum Steel Corp
Priority to US316116A priority Critical patent/US3288611A/en
Priority to DE1964A0047312 priority patent/DE1458331B1/de
Priority to BE654353D priority patent/BE654353A/xx
Priority to FR991314A priority patent/FR1419749A/fr
Priority to GB42009/64A priority patent/GB1073590A/en
Application granted granted Critical
Publication of US3288611A publication Critical patent/US3288611A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • BPERFORMING OPERATIONS; TRANSPORTING
    • B23MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23KSOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K35/00Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
    • B23K35/22Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by the composition or nature of the material
    • B23K35/24Selection of soldering or welding materials proper
    • B23K35/30Selection of soldering or welding materials proper with the principal constituent melting at less than 1550 degrees C
    • B23K35/3053Fe as the principal constituent
    • B23K35/308Fe as the principal constituent with Cr as next major constituent
    • B23K35/3086Fe as the principal constituent with Cr as next major constituent containing Ni or Mn

Definitions

  • This invention relates to an improved high strength martensitic stainless steel and in particular to a m-art sitic high strength stainless steel having an optimum combination of form'ability, heat treatment, welding and corrosion resistance characteristics.
  • stainless steels have assumed an increasingly important role as structural materials, especially in the transportation industry. These stainless steels, well known for some time, have recently been applied in this field because of their combination of strength and corrosion resistance.
  • the A181 200, 300 and 400 Series have been utilized, depending upon the combination of properties desired.
  • the A151 400 Series martensitic stainless steels have been utilized, an example of which is AISI Type 410.
  • the use of the martensitic stainless steels has been fairly limited, however, because of the difiiculties encountered from the fabrication standpoint.
  • the martensitic stainless steels were characterized by having a limited amount of cold workability, necessitating rather long heat treatments at subcritical temperatures in order to confer an adequate deg-rec of cold workability to the steel.
  • both p-rewelding and postwelding heat treatments were necessary in order to confer upon the steel an adequate degree of strength and ductility in actual use.
  • These steels are characterized by having a relatively high carbon content for strength purposes and a low chromium content in order to avoid the formation of delta ferrite therein. As a result, the corrosion resistance of these materials was severely limited.
  • the steel of the present invention does not require the delicate metallurgical balance and is not a precipitation hardening stainless steel, yet possesses a martensitic microstructure with optimum formability together with high strength, adequate corrosion resistance, simplified heat treatment and excellent weldability, thereby combining advantageous properties of both the 300 and 400 Series stainless steels without the particular disadvantages encountered in the PH steels.
  • the steel of the present invention possesses better modulus values than temper rolled austenitic stainless steels, which modulus values, in the steel of the present invention, are nondirectional thereby making the steel of the present invention highly attractive for structural applications.
  • An object of the present invention is to provide a high strength, martensitic, corrosion resisting steel.
  • Another object of this invention is to provide a high strength, martensitic, corrosion resisting steel characterized by having low hardness, good ductility and high strength which can be developed by a simplified heat treatment.
  • Another object of this invention is to provide a high strength, martensitic, corrosion resisting steel having an optimum combination of forming and welding character istics and which can be employed as a structural member in the transportation industry.
  • a more specific object of the present invention is to provide a martensitic, high strength, corrosion resisting steel containing carbon, silicon, manganese, chromium, nickel and titanium, in which the titanium to carbon ratio and the silicon content are limited to specific ranges.
  • the steel of the present invention has a composition which includes from traces to 0.1% carbon, from traces to 0.5% silicon, from traces to 1% manganese, from 10.5% to 14% chromium, from 3% to 6% nickel, titanium in an amount equal to from 8 to 18 times the carbon content, and the balance essentially iron with incidental impurities.
  • the alloying components contained therein perform functions as related hereinafter.
  • the carbon content of the present invention is limited to an amount between traces and 0.1%. It is preferred to maintain the carbon content as low as possible and preferably not above 0.05%, in order to obtain a substantially carbon-free martensite after cooling to room temperature from a low austenitizing heat treatment temperature. While carbon contents in excess of 0.05% and up to about 0.1% can be utilized, these higher carbon contents must be balanced with the titanium content'so as to insure an exceedingly low or substantially carbon-free martensitic structure which will have low hardness and good ductility.
  • the steel of the present invention contains silicon which must be limited to about 0.5% maximum. Silicon has been found to be a potent solution hardener which can have an embrittling effect and, as a result thereof, the silicon content must be maintained at no greater than 0.5 in order to obtain the proper degree of formability in the steel. While the silicon contents are preferably maintained low, it will be recognized that some silicon will always be present. Optimum results appear to be obtained where the silicon content is maintained from traces to about 0.30%. It is also preferred to maintain the manganese content on the low side in order to insure adequate rollability and good ductility to the material. In this respect, it has been found that up to about 1.0% manganese can be utilized; however, it is preferred to maintain the manganese content at less than 0.5%. Moreover, with low manganese and low silicon contents combined with a low carbon content, the cleanliness of the steel is greatly improved which aids in the corrosion resistance inherent .within the steel, but not fully developed unless the silicon,
  • the steel of this invention contemplates a chromium content within the range between about 10.5% and 14% and preferably within the range between 11% and 13%. At least 10.5% chromium is necessary in order to confer an adequate degree of corrosion resistance, whereas increasing the chromium content to beyond 14%, results in the formation of a duplex microstructure which will include delta ferrite, a component which will not transform to maitensite upon subsequent cooling to room temperature. Moreover, such a duplex microstructure which contains delta ferrite, adversely affects the mechanical properties, especially in the transverse direction, and re sults in increased difliculties during hot working operations. The optimum combination between corrosion resistance, strength, formability stability, appears to be obtained when the chromium content is present within the range between about 11% and about 13%.
  • the steel of the present invention contains nickel in an amount between 3% and 6 and preferably within an amount be- At least 3% nickel is necessary in the steel of the present invention to form the austenite phase and to suppress the formation of delta ferrite, whereas nickel contents in excess of about 6% may stabilize the austenitic structure to a sufficient degree that austenite may be retained upon cooling to room temperature.
  • the nickel is increased to beyond about 6%, some age hardening may be apparent within the steel of the present invention, depending upon the relative level of the carbon and titanium present. Optimum results appear to be obtained when the nickel content is maintained within the range between about 3.5% and about 5.0%.
  • Titanium is also included within the steel of the present invention and functions to balance the composition by uniting with the carbon and nitrogen contents so that 'when the steel is cooled to room temperautre a substantially carbonand nitrogen-free martensite is formed, which is characterized by low hardness and good ductility. For this reason, it is desirable to have the minimum titanium content present within the steel at about 8 times the carbon contained therein. While larger amounts of titanium can be utilized, for example a titanium content up to about 18 times the carbon content, higher titanium contents should be avoided because of the possibility of forming an age hardening component within the steel of the 'present'invention. This age hardening component depends upon the relative amounts of titanium and nickel present within the composition.
  • the steel of the present invention may optionally contain columbium, molybdenum or vanadium for special purposes, it being noted that the columbium can be substituted for the titanium on the basis of about 2:1. Vanadium may also be employed to unite with the carbon thus removing it from solution within the martensite and thereby obtain relatively the same characteristics. Molybdenum may also be optionally added to the steel of the present invention, where added resistance to a corrosive environment in which a halogen ion is present, is desired. Molybdenum also improves the high temperature properties of the steel. The balance of the steel cornprises essentially iron with the usual impurities normally found in steel-making practice.
  • the steel of the present invention may be made by any of the well-known steel-making practices, for example, the carbon electrode electric arc furnace, the details of which are well known in the art and need not be set forth in detail.
  • the steel of the desired composition as set forth hereinbefore in Table I, is cast into ingots which are hot rolled to any desired shape, for example, bloom, bar, billet, slab and fiat rolled products. After descaling, the steel may be cold rolled to finish gauge, for example, into the form of strip, wire, plate, sheet, tube, bar, rod or any other semi-finished mill product.
  • the steel of the present invention can be cold rolled in excess of 75% reduction in cross sectional area in fiat rolled product form Without any intermediate reannealing.
  • the steel in the form of wire has been drawn to effect a reduction in the cross sectional area of up to 99% without any intermediate reannealing.
  • the steel may be heat treated in order to obtain adequate ductility for any of the various fabricating procedures, for example, drawing, bending and joining. It is preferred to heat treat the steel of the present invention after cold working to the finished mill product by heating to a temperature within the range between about 1400 F. and about 1600 F. After heating in this temperature range, the steel may be quenched in order to form a substantially completely martensitic microstructure which is characterized by high strength, low hardness, good formability, and with excellent welding characteristics.
  • Table II illustrates the typical mechanical properties of the steel of this invention, said steel having a composition which includes: 0.015% carbon, 0.13% manganese, 0.061% silicon, 11.0% chromium, 4.0% nickel, 27% titanium, and the balance essentially iron with incidental impurities.
  • AISI Type 430 stainless steel a ferritic stainless steel; AISI Type 302, an austenitic stainless steel, and AISI Type 410, a martensitic stainless steel, are included.
  • the titanium to carbon ratio becomes very important especially where the transverse bending properties of the steel are considered.
  • the transverse bending properties are those properties which are measured by the ratio of the bend radius to the thickness of the steel when said steel is deformed to produce a 135 bend without failure in the steel. It is considered that the bend ratio must be limited to not more than about 2 in order for the steel to have adequate transverse bendability which is a measure utilized in determining the formability characteristics of the steel.
  • Table IV contains the chemical composition of a series of steels having a varying titanium to carbon ratio, some of which are outside the scope of this invention, and which were utilized in order to evaluate the formability characteristics of the steel of the present invention.
  • the steel of the present invention can be cold worked to varying degrees Without the necessity of an intermediate annealing heat treatment. This results from the fact that the low carbon martensite has a very low rate of work hardening which is directly.
  • the steels having the composition set forth in Table IV were rolled to varying sheet thicknesses and were subjected to the standard hardness, tensile and bend tests. These tests are set forth in the following Table V. In each instance, the steel was given an annealing heat treatcontrary to the AISI 300 Series stainless steels. Referment at a temperature of 1400 F. following which the ence may be had to Table III which shows the effect of steel was air cooled to room temperature.
  • the steel of the present invention possesses excellent welding characteristics.
  • the steel having a composition of .015 carbon, .0l9% silicon, .14% manganese, 10.92% chromium, 4.05% nickel, .25 titanium, and the balance essentially iron with impurities was cold rolled to strip material having a thickness of 0.062", annealed and was welded by the Tungsten Inert Gas Process, there being no filler metal added during such welding operation.
  • the steel was welded without benefit of a prewelding heat treatment and the properties set forth hereinafter in Table VI were the properties in the condition stated without benefit of a postwelding heat treatment.
  • the steel of the present invention exhibits corrosion resistance which compares quite favorably with both AISI Type 430 and Type 410.
  • the steel having a composition within the range set forth hereinbefore in Table I was subjected to the following listed acid solutions ference is noted in the elongation as measured, the locafor the time periods indicated and the weight loss calcution of the fracture was in the base metal which clearly lated in inches penetration per month was determined both indicates the outstanding welding characteristics of this for the steel of the present invention, as well as standard steel.
  • An aging at 1000 F. for 5 minutes shows a slight AISI Types 410 and 430.
  • the as welded and the welded and heat treated conditions of the metal exhibit properties quite similar to those of the parent metal, both in tion possesses a corrosion resistance which is more desirable than either that of AISI Type 410 or Type 430.
  • the steel of the present invention has been utilized in flat rolled product form, for example, sheets and plates, and has been formed specifically into corner posts for automotive trailers, and in all operations, that is, melting through semi-finished mill products and into the final fabricated form, standard equipment presently in use in these industries today has been utilized Without difiiculty.
  • a martensitic stainless steel consisting essentially of from traces to 0.10% carbon, traces to 0.5 silicon, traces to 1.0% manganese, from 10.5 to 14% chromium, from 3% to 6% nickel, from 8 to 18 times the carbon content of titanium, and the balance essentially iron with incidental impurities.
  • a martensitic stainless steel consisting essentially of about 0.015% carbon, about 0.13% manganese, about 0.061% silicon, about 11.0% chromium, about 4.0%
  • nickel about 0.27% titanium, and the balance essentially iron with incidental impurities.
  • a martensitic stainless steel consisting essentially of from traces to 0.10% carbon, t-races to 0.5% silicon, traces to 1.0% manganese, from 10.5% to 14% chromium, from 3% to 6% nickel, from 0.2% to 0.75% titanium, the ratio of titanium to carbon being Within the range between about 8 to about 18, and the balance essentially iron with incidental impurities.
  • a composition suitable for welding dissimilar metals characterized by a low rate of Work hardening, good f-ormability and corrosion resistance, said composition consisting essentially of from traces to 0.1% carbon, from traces to 1% manganese, from traces to 0.5% silicon, from 10.5% to 14% chromium, from 3% to 6% nickel, from 8 to 18 times the carbon content of titanium, and the balance essentially iron with incidental impurities.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Heat Treatment Of Steel (AREA)
  • Heat Treatment Of Sheet Steel (AREA)
US316116A 1963-10-14 1963-10-14 Martensitic steel Expired - Lifetime US3288611A (en)

Priority Applications (5)

Application Number Priority Date Filing Date Title
US316116A US3288611A (en) 1963-10-14 1963-10-14 Martensitic steel
DE1964A0047312 DE1458331B1 (de) 1963-10-14 1964-10-13 Verwendung einer martensitischen,rostfreien Stahllegierung als Werkstoff für geschweisste Gegenstände
BE654353D BE654353A (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html) 1963-10-14 1964-10-14
FR991314A FR1419749A (fr) 1963-10-14 1964-10-14 Perfectionnements apportés aux aciers inoxydables martensitiques
GB42009/64A GB1073590A (en) 1963-10-14 1964-10-14 Improvements in or relating to martensitic stainless steel

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US316116A US3288611A (en) 1963-10-14 1963-10-14 Martensitic steel

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US3288611A true US3288611A (en) 1966-11-29

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US (1) US3288611A (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html)
BE (1) BE654353A (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html)
DE (1) DE1458331B1 (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html)
GB (1) GB1073590A (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html)

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3355280A (en) * 1965-06-25 1967-11-28 Int Nickel Co High strength, martensitic stainless steel
US3373015A (en) * 1965-03-16 1968-03-12 Armco Steel Corp Stainless steel and product
US3408178A (en) * 1967-06-27 1968-10-29 Carpenter Steel Co Age hardenable stainless steel alloy
US3933479A (en) * 1974-10-10 1976-01-20 United States Steel Corporation Vanadium stabilized martensitic stainless steel
US4058417A (en) * 1975-02-24 1977-11-15 General Electric Company Turbine bucket alloy
DE4039538A1 (de) * 1989-12-11 1991-06-13 Kawasaki Steel Co Hochfester martensitischer rostfreier stahl und verfahren zu seiner herstellung
US20040154706A1 (en) * 2003-02-07 2004-08-12 Buck Robert F. Fine-grained martensitic stainless steel and method thereof
US6890393B2 (en) 2003-02-07 2005-05-10 Advanced Steel Technology, Llc Fine-grained martensitic stainless steel and method thereof
US20100143067A1 (en) * 2008-11-03 2010-06-10 Powers Fasteners, Inc. Anchor bolt and method for making same

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5135447B2 (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html) * 1972-10-26 1976-10-02

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1538337A (en) * 1919-02-27 1925-05-19 Ludlum Steel Co Alloy
US2999039A (en) * 1959-09-14 1961-09-05 Allegheny Ludlum Steel Martensitic steel

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AT146720B (de) * 1931-06-23 1936-08-10 Krupp Ag Herstellung von Gegenständen, die besondere Festigkeitseigenschaften, insbesondere eine hohe Schwingungsfestigkeit besitzen müssen und/oder hohe Beständigkeit gegen Brüchigwerden durch interkristalline Korrosion aufweisen sollen.

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1538337A (en) * 1919-02-27 1925-05-19 Ludlum Steel Co Alloy
US2999039A (en) * 1959-09-14 1961-09-05 Allegheny Ludlum Steel Martensitic steel

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3373015A (en) * 1965-03-16 1968-03-12 Armco Steel Corp Stainless steel and product
US3355280A (en) * 1965-06-25 1967-11-28 Int Nickel Co High strength, martensitic stainless steel
US3408178A (en) * 1967-06-27 1968-10-29 Carpenter Steel Co Age hardenable stainless steel alloy
US3933479A (en) * 1974-10-10 1976-01-20 United States Steel Corporation Vanadium stabilized martensitic stainless steel
US4058417A (en) * 1975-02-24 1977-11-15 General Electric Company Turbine bucket alloy
DE4039538A1 (de) * 1989-12-11 1991-06-13 Kawasaki Steel Co Hochfester martensitischer rostfreier stahl und verfahren zu seiner herstellung
US20040154706A1 (en) * 2003-02-07 2004-08-12 Buck Robert F. Fine-grained martensitic stainless steel and method thereof
US6890393B2 (en) 2003-02-07 2005-05-10 Advanced Steel Technology, Llc Fine-grained martensitic stainless steel and method thereof
US6899773B2 (en) 2003-02-07 2005-05-31 Advanced Steel Technology, Llc Fine-grained martensitic stainless steel and method thereof
US20100143067A1 (en) * 2008-11-03 2010-06-10 Powers Fasteners, Inc. Anchor bolt and method for making same

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Publication number Publication date
BE654353A (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html) 1965-04-14
DE1458331B1 (de) 1970-05-21
GB1073590A (en) 1967-06-28

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