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
  • C22C38/04—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
  • C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium

Definitions

• the invention relates to the use of a steel as a material for components with a cross section from about. 4 0 cm 2 , which after hot forming by rolling, forging or pressing at final deformation temperatures up to about 1000 ° C or annealing temperatures up to about 1000 ° C and then cooling in still or moving air, optionally after controlled cooling, a ferritic-pearlitic structure with about 5 to 20% ferrite, remainder pearlite and a yield or 0.2 limit of at least 580 N / mm 2 and a notched bar impact work measured on ISO-U samples of at least 25 J.
• Such a steel specified in said patent specification with relatively high proportions of vanadium, aluminum and nitrogen within the analysis limits is said to have a 0.2 limit of 578 N / mm 2 and a tensile strength of 865 N when placed in air on a rod rolled to 155 mm 0 / mm2 and have a notched bar impact energy measured on DVM samples of 35 J.
• the object of the invention is to provide steel for components with even higher strength and at least as high toughness, which should be achievable by simple cooling of the components in air after hot forming or an annealing process without further heat treatment.
• the invention is based on the following considerations shown below:
• the percentage of pearlite in steel increases, and with it its strength, hardness and brittleness; up to about 0.6% carbon content, at the same time its conversion rate decreases when it cools down from the final deformation temperature or annealing temperature.
• manganese and chromium are very soluble in d, iron and increase strength without embrittlement by increasing the hardness of the ferrite component, which is necessary to achieve good toughness.
• manganese forms carbide which deteriorates the later machinability of the component and lowers the eutectoid point far less than chromium; Even with relatively large amounts of manganese, the formation of cementite is avoided, which would have a particularly adverse effect on the subsequent processing of the component.
• Manganese also delayed as mentioned above, a carbon content to 0.6%, the conversion speed during cooling of the component from Endverformungstemperatur or annealing temperature of about 1000 ° C, but at the same time lowered mwandlungstemperaturen all U; within a large Abkühl Ecks Kunststoffes also provides an almost constant with pearlitisation dependent on the same high strength, a, also for components with through un- t eretzliche wall thickness caused by different cooling at various points. Due to the high affinity of manganese for impurities such. B.
• the conversion rate can be further slowed down by one or more powers of ten.
• Micro additions of vanadium and aluminum and possibly also of zirconium and niobium in appropriate coordination to the nitrogen content cause nitride and carbonitride formation as crystallization nuclei for fine grain formation, a good distribution of the ferrite, as well as precipitation hardening in the ferrite, an increase in the yield strength / breaking strength ratio and also an increase of firmness.
• Said process takes place in the case of a component which is unaffectedly cooled in room air from a final deformation temperature or annealing temperature of approximately 1000 ° C., depending on the wall thickness or thickness of the component at a certain speed, which can be achieved by lightly blowing on, for example by means of an air shower, can advantageously be shortened.
• such a steel is to be used for a component, the carbon and manganese content of which is primarily determined so that the desired strength can be achieved, whereby manganese can also be replaced to a certain extent by chromium.
• the fine-grain-forming and precipitation-hardening alloy components must also be coordinated with each other as well as with regard to the carbon and manganese content.
• so much boron and / or molybdenum must be added that the dimensions and Production conditions of the component adapted cooling conditions with slow or faster cooling in still or moving air sets such pearlization as the desired toughness values require.
• the stated values indicate that with such a simply treated manganese steel, practically strength and toughness values can be achieved as with a tempered steel, the latter with the same dimensions (diameter 250 mm) to achieve the same strength and toughness values at least three times would have to be so highly alloyed with alloying elements such as chromium, nickel, molybdenum and others, which in their then necessary proportions, in contrast to those of the manganese steel used according to the invention, would considerably impair the later machinability of the component.
• the steel proposed according to the invention provides these advantages particularly in the production of components with larger cross sections of approximately 40 cm 2 onwards, such as crankshafts or camshafts of internal combustion engines and the like, alternatively stressed machine parts.

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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 Articles (AREA)
• Heat Treatment Of Steel (AREA)

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Publications (2)

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Cited By (7)

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Citations (2)

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• 1982
  • 1982-01-16 DE DE19823201204 patent/DE3201204C2/de not_active Expired
• 1983
  • 1983-01-07 EP EP83100080A patent/EP0085828B1/fr not_active Expired
  • 1983-01-12 JP JP237483A patent/JPS58123856A/ja active Granted

Patent Citations (2)

Non-Patent Citations (2)

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