Classifications

• • 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
  • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
  • C21D8/10—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of tubular bodies

Definitions

• ABSTRACT Method of producing quenched and tempered hollow steel structural members of polygonal cross section includes the steps of hot rolling a hollow steel tube, austenitizing the tube, water quenching it, reheating the tube to a tempering temperature just below the lower critical transformation temperature, and rolling the tube to the desired polygonal cross section while holding the temperature of the member at the tempering temperature.
• the chemical composition of the steel in the tube may be any steel which is suitable for the production of This invention relates to hollow steel structural tub- 5 q n h and tempered ubes.
• a Suitable composition ing, and more particularly t nch d d t d is a silicon-aluminum killed steel, having a composition structural steel tubing of polygonal cross section such bf about 020% Carbon, t-45% rhahgahese and 006% as square or rectangular.
• Tubular structural stccls pro- Vahadhlrh- This steel composition is martehsitic andhalted in this manner developed high yield strengths hibits g weldabihtyand high tensile strengths, together with high notch l0 Austehittzihg is accomplished at a temperature toughness at l tempetatures greater than the A temperature of the steel in the tube.
• the austenitization is carried out in hot rolling in a tube-mill, which tube is formed into the a gas'fired furhaee in ah excess air atmosphere r a desired cross sectional dimensions and shape by passsuffieteht time b assure uniform heating of the tubeing it through a squaring pass after the round tube has water qttehehmg ts aeeemphshed by Passing the tube been formed.
• the squaring or sizing operation is carthrough a sertes of p y quench rthgs to Provide 100% i d out at a temperature of from about llOOO to surface coverage of the tube circumference
• the tube 1500F is
• the tube is hot rolled in is quenched to a temperature of about 1500b, but y a conventional manner, then reheated to about be quenched to y temperature below 2000K 1300F-.,- and passed through a sizing mill to form the
• the tempering temperature is j above the stress b i a polygonal crosslsootion H treatment of relieving temperature and just below the lower critical the finished shapes has resulted in distortion of the flat transformation temperature of the steel that is, l faces of the shapes beyond acceptable commercial limbelow the el temperature For most steels, pe g i
• the physical properties such as Strongth and will be carried out at a temperature between about toughness of these tubes are limited to those properties 1 1500b and 1225OF-
• the tube ls pe for a Perted which can be attributed to chemical composition alone.
• This 18 nor- This invention is predicated upon my development of a e wtth a 512mg haylhg a number or stands a weldable waterquenched and tempered structural wtth sqbarrhg'bassestube of polygonal cross section to meet the demand for h shapes Pr y thrs rhethbd e free of higherstrength structural materials with superior notch ht a e high hbteh toughness, g ytetd strength toughness properties and ultimate Strength.
• the lower vanadium Stool structural members content tubes were austenitized at l600F, and the The method-of the invention consistS higher vanadium tubes at l650F, in a walking beam H lli a ll Steel b i substantially furnace for 100 minutes per inch of wall thickness.
• This oval or circular cross section by any conventional was followed y P y quenching with q h water at tube rolling method; a temperature of about 92F.
• the one-half Inch wall b, A i i i h b tubes were quenched at a speed of 26 ft. per minute 0. Water quenching the tube to about 150F; and the three-eighths inch wall tubes at 36 ft. per mind.
• Table 2 shows the mechanical properties from two as-rolled tensile tests and tests from each tube quenched and tempered according to this process. From this data, it is clear that 75,000 psi minimum 4 above the stress relieving temperature and below the Ac temperature; e. tempering said tube at said tempering temperature; f. rolling said tube to the desired polygonal crossyield strength may be attained in all wall thicknesses to 5 section while within said tempering temperature one-half inch. range; and
• a method according to claim 2 wherein said austenitizing temperature is from about 1600F to about 1750F.
• tempering temperature is from about 1150F to about 1225F.

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

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Publications (1)

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Cited By (3)

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Citations (3)

• 1972
  • 1972-09-25 US US00291854A patent/US3779817A/en not_active Expired - Lifetime
• 1973
  • 1973-09-17 GB GB4356073A patent/GB1398062A/en not_active Expired
  • 1973-09-22 JP JP48106559A patent/JPS49123963A/ja active Pending
  • 1973-09-24 CA CA181,717A patent/CA986824A/en not_active Expired
  • 1973-09-24 IT IT69811/73A patent/IT996728B/it active
  • 1973-09-25 DE DE19732348152 patent/DE2348152A1/de active Pending
  • 1973-09-25 FR FR7334372A patent/FR2200360B1/fr not_active Expired

Patent Citations (3)

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