Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D13/00—Centrifugal casting; Casting by using centrifugal force
  • B22D13/10—Accessories for centrifugal casting apparatus, e.g. moulds, linings therefor, means for feeding molten metal, cleansing moulds, removing castings
  • B22D13/101—Moulds
• • 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
  • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
• • 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
  • C22C38/04—Ferrous alloys, e.g. steel alloys containing 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
  • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
  • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
  • C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
• • 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
  • C22C38/46—Ferrous alloys, e.g. steel alloys containing chromium with nickel with vanadium

Definitions

• the present invention relates to a ferritic alloy steel used for making pipe molds.
• low alloy steels like AISI 4130 (1% chromium, 0.20% molybdenum) and 21CrMo10 (2.25% chromium, 0.35% molybdenum) are considered the workhorse grades for pipe mold steel.
• AISI 4130 chemistry is provided from Aerospace Structural Metals Handbook , (1986), pp 1-20.
• 21CrMo10 chemistry is provided from Stahl gleichel (Key to Steel) (1977), pp 192-207.
• the present invention relates to a ferritic alloy steel with high hardenability, high toughness, and high ductility for making pipe molds used for centrifugally casting pipe.
• the steel of the present invention may preferably be used to make pipe molds or other products undergoing high thermal stresses.
• Another object of the invention is to provide a steel for producing pipe molds with improved service life for centrifugally casting pipe.
• a further object of the invention is to provide a steel for producing pipe molds with improved service life for centrifugally casting pipe, with the pipe mold steel having a reduced carbon level and vanadium, manganese and silicon.
• Another object of the invention is to produce a steel of substantially high hardenability with the addition of manganese and silicon to the alloy system.
• the present invention is directed to a low alloy ferritic steel for making pipe molds with improved service life that are used for centrifugally casting pipe.
• Pipe molds made from this steel can be used to centrifugally cast both small and large diameter pipe.
• the steel preferably may be used to make pipe molds or other products undergoing high thermal stresses.
• the present invention relates to a steel with high hardenability, high toughness, and high ductility. This invention creates an alloy that is a modification of the AISI 4130 alloy system.
• the alloying elements manganese and silicon, together with phosphorus, sulfur, chromium, molybdenum, nickel, and vanadium, provide desirable properties for long service life of pipe molds made with this steel.
• the combined effect of the use of manganese and silicon within the specified ranges, coupled with the other elements, promotes the enhancement of properties in the low chromium steel.
• the weight percentages of the steel of the present invention which has been designated “0303” (Khare V), are set forth in Table 2, below: TABLE 2 Element 0303 (Khare V) Carbon 0.16-0.22 Manganese 1.00-1.50 Silicon 1.15-1.45 Phosphorus 0.015 Maximum Sulfur 0.015 Maximum Chromium 0.80-1.10 Molybdenum 0.20-0.30 Nickel 0.50 Maximum Vanadium 0.03-0.08 Iron Balance
• the alloying of the steel with manganese and silicon in the ranges specified promotes the desired toughness, hardenability, and ductility in the as-heat treated pipe molds.
• Two trials of three variations of 0303 (Khare V) steel test bars 21 ⁇ 2 OD ⁇ 21′′ long were forged and tested for properties.
• the forged 0303 (Khare V) steel was prepared and heat treated as follows. For the K2038 melt, the steel was austentized at 1650° F. for 2 hours, water quenched, and tempered at 1150° F. for 2 hours. For the K2039 melt, the steel was normalized at 1650° F. for 2 hours, austentized at 1600° F. for 2 hours, water quenched, and tempered at 1200° F. for 2 hours. The steel was then tested for mechanical properties. The mechanical properties of the 0303 (Khare V) steel are set forth in Table 5, below.
• the carbon level of the steel chemistry of the present invention is lower than in the conventional AISI 4130 range of 0.28-0.33%.
• the reduced carbon results in a reduction in hardness and strength coupled with an increase in toughness and ductility in the as-heat treated pipe mold.
• the reduced carbon also helps reduce the internal stresses of the steel of the present invention. This will mean that there is greater stability after tempering in the pipe molds made from the steel of the present invention. As such, the pipe molds will be less susceptible to quench cracking during the manufacture or due to thermal fatigue, and distortion during production. These combined effects greatly improve the service life.
• Vanadium in the range of 0.03-0.08% is added to the steel of the present invention to give the steel fine austenitic grain size and prevent softening during temper. Vanadium was not included in the AISI 4130 grade of steel. The fine grain size working in conjunction with the low stresses resulting from the use of reduced carbon enhances the stability of the steel of the present invention. Vanadium, along with the alloying elements manganese and molybdenum, helps maintain the desired level of post-temper hardness.
• Manganese in the 1.00-1.50% range provides a high carbon/manganese ratio. Manganese in this range promotes deep hardening at the desired levels without adversely affecting the desired properties of toughness and ductility. This deep hardening is caused by the element manganese very strongly retarding the transformation of austenite. Manganese also lures the transformation temperature, thus, giving the steel fine grain size, with improved yield strength and impact values. As an added benefit, it increases the Pearlite content for the given carbon level, thus, raising strength without sacrificing weldability.
• Silicon provides Solid Solution strengthening and improves high temperature oxidation resistance. Silicon will also counterbalance the possible temper embrittlement effect caused by enhanced manganese.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Heat Treatment Of Articles (AREA)
• Moulds For Moulding Plastics Or The Like (AREA)

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• 2002
  • 2002-12-10 WO PCT/US2002/039385 patent/WO2003050319A1/fr not_active Ceased
  • 2002-12-10 AU AU2002362119A patent/AU2002362119A1/en not_active Abandoned
  • 2002-12-10 AU AU2002357799A patent/AU2002357799A1/en not_active Abandoned
  • 2002-12-10 WO PCT/US2002/039333 patent/WO2003050318A1/fr not_active Ceased
  • 2002-12-10 US US10/315,875 patent/US20030147768A1/en not_active Abandoned
  • 2002-12-10 US US10/315,873 patent/US20030156966A1/en not_active Abandoned

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