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
  • C22C38/30—Ferrous alloys, e.g. steel alloys containing chromium with cobalt
• • 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
  • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
  • C21D9/22—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for drills; for milling cutters; for machine cutting tools

Definitions

• the present invention relates to tools consisting of high-speed steel castings, which enable the advantages stated hereinbefore of a molding process to be achieved because they give reliably the same and in many cases a better performance than tools of hot-worked steels of the same type.
• the carbon content does not only depend on the grade of steel but also on the intended use.
• tools consisting of high-speed steel castings mainly subjected to abrasive stresses should have a more highly increased carbon content whereas in tools subjected to considerable impact or bending stresses the carbon content should only slightly exceed the upper limit specified for forged tools of the same type.
• these castings must be hardened at the same high hardening temperature as the hot-worked steel of the same type having a lower carbon content.
• the invention provides tools consisting of highspeed steel castings and having at least the same performance as tools of hot-worked steels of the same type, the castings consisting of a steel having a carbon content which is 0.1-0.4% over the upper allowable limit of the carbon content and in cases in which a particularly high toughness is desired is at the upper limit of the carbon content for the hotworked steel of the same type or up to 0.1% above this limit.
• the steel castings may have a carbon content which is at the upper limit of the carbon content for the hot-worked steel of the same type to 0.4% above said limit.
• the castings having the aforestated carbon limits are subjected to a diffusion annealing at 1050-1200" C. for one to eight hours before they are hardened. Hardening is effected at the same temperature which is used for tools made from hot-worked steels of the same type having a normal carbon content.
• the tools are suitably preheated to 850 C., then heated in a salt bath furnace, quenched in oil and tempered twice at 540580 C. for periods of one hour each.
• the measures recommended according to the invention can be applied to advantage to all previously known types of high-speed steel and result in many cases, particularly in high-speed steels containing cobalt, to surprising increases in performance by as much as 50%.
• Example 1 From a high-speed steel which, if used in the hotworked condition should have the following composition tungsten 12%, chromium 4%, vanadium 4%, cobalt 5%, carbon 1.25-1.4%, cast tools were made which had the following composition: tungsten 12%, chromium 4%, vanadium 4% cobalt 5%, carbon 1.65%.
• Tempering Two tempering treatments of one hour each at 570 C.
• Tools of the foregoing composition cast by the precision investment process of the invention had a milled length of 2400 m. on the average. This is a surprisingly high improvement as against the performance shown by tools made of forged steel with an average milled length of- Example 2
• Tempering Two tempering treatments of about one hour each at 550580 C.
• Hob cutters are mushroom-shaped tools which are used for machining parts of the substructure for railroads.
• edge life of the cast tools after a suitable heat treatment has proven better than that 'of the conventional tools of similar, forged steel.
• the life of the cast chasers and threading dies is also longer than that of tools of forged high speed steel.
• Example 3 From a high-speed steel which, if used in the hotworked condition should have the following composition: tungsten 9.5%, chromium 4.3%, molybdenum 5.2%, vanadium 3.5%, cobalt 10.5%, carbon 1.21.3%, cast tools having the following composition were madetungsten 9.5%, chromium 4.3%, molybdenum 5.2%, vanadium 3.5%, cobalt 10.5%, carbon: 1.3% for groove cutters, 1.55% for barrel fine borer tips.
• Tempering Two tempering treatments of about 1 hour each at 5605-90 C.
• the life of the cast tips of the barrel borers was twice to three times the life of forged tools made from similar material.
• Example 4 From a high-speed steel which, if used in the hotworked condition should have the following composition: tungsten 18.5% chromium 4.3%, vanadium 1%, carbon 0.70- 0.78%, cast high-speed milling cutters having the following composition were madetungsten 18.5 chromium 4.3% vanadium 1% carbon 0.78%
• Tempering Two tempering treatments of about one hour each at 550-580 C.
• the cast milling cutters had wearing properties at least equivalent to the previously used tools made from hot-formed steel.
• Example 5 Froma high-speed steel which, if used in the hotworked condition should have the following composition: tungsten 6.5%, molybdenum 5%, chromium 4.3%, vanadium, 2%, carbon 0.78-0.86%, cast tools having the following composition were made-tungsten 6.5%, molybdenum 5 chromium 4.3%, vanadium 2%, carbon: 0.86% for profile milling cutters, 0.90% for guideway milling cutters.
• Tempering Two tempering treatments of about one hour each at 540570 C.
• Example 6 From a high-speed steel which, if used in'the hotworked condition should have the following composition: tungsten 6.5%, molybdenum 5%, chromium 4.3%, vanadium 2%, cobalt 5% and 'carbon 0.790.86%, cast rough cutters for woodworking were made with the following composition-tungsten 6.5%, molybdenum 5%, chromium 4.3%, vanadium 2%, cobalt 5%, carbon 0.85%.
• Tempering Two tempering treatments of about one hour each at 550580 C.
• Rough cutters for woodworking operate at very high rotary and cutting speeds. If the tool encounters hard portions in the wood, such as knots, there is a great danger of brittle failure. Under these adverse conditions, cast tools subjected to the heat treatment of the invention have been just as suitable as tools made from wrought high-speed steel.
• a process for the production of cast high-speed steel tools having a carbon content which is at the permissible upper limit of carbon of the hot-worked steel of the same composition to 0.4% above said limit comprising annealing the cast tools from 1-8 hours at 1050 C. to 1200 C. before hardening.
• a process for the production of cast high-speed steel tools having a carbon content which is about 0.1 to 0.4% above the permissible upper limit of carbon of the hotworked steel of the same composition comprising annealing the cast tool from 1-8 hours at 1050 C. to 1200 C. before hardening.
• a process for the production of cast high-speed steel tools having a carbon content which is at the permissible upper limit of carbon of the hot-worked steel of the same composition, to 0.1% above said limit comprising annealing the cast tool from 1-8 hours at 1050 C. to 1200 C. before hardening.
• a process for the production of cast high-speed steel tools as set forth in claim 1 in which two tempering treatments of about one hour each are carried out at a temperature between 540 C. and 580 C. after the hardening treatment.
• a process for the production of cast high-speed steel tools as set forth in claim 1 in which the tools are preheated to about 850 C. before the hardening treatment and two tempering treatments of about one hour each are carried out at a temperature between 540 C. and 580 C. after the hardening treatment.
• a process for the production of cast high-speed steel tools consisting essentially of 12% tungsten, 4% chromium, 4% vanadium, 5% cobalt, 1.65% carbon, the balance essentially of iron in which the cast tools are diffusion annealed for one hour at 1100 C. preheated at 850 C., hardened by quenching in oil after heating in a salt bath furnace at 12301260 C. and subjected after the hardening to two tempering treatments for one hour each at 570 C.
• a process for the production of cast high-speed steel tools consisting essentially of 18% tungsten, 4.3% chromium, 1.6% vanadium, 1% molybdenum, 5% cobalt and 0.951.0% carbon, the balance essentially of iron in which the cast tools are diffusion annealed for one to eight hours at 10501200 C., hardened by quenching in oil after heating in a salt bath furnace at 1250-1280 C. and subjected after the hardening to two tempering treatments for one hour each at 550580 C.
• a process for the production of cast high-speed steel tools consisting essentially of 18% tungsten, 4.3% chromium, 1.6% vanadium, 1% molybdenum, 5% cobalt, 0.90% carbon, the balance essentially of iron in which the cast tools are diifusion annealed for one to eight hours at 10501200 C. hardened by quenching in oil after heating in a salt bath furnace at 12501280 C. and subjected after the hardening to two tempering treatments for one hour each at 550580 C.
• a process for the production of cast high-speed steel tools consisting essentially of 9.5% tungsten, 4.3% chromium, 5.2% molybdenum, 3.5% vanadium, 10.5% cobalt and 1.55% carbon, the balance essentially of iron 6 in which the cast tools are diffusion annealed for one to eight hours at 10501200 C., hardened by quenching in oil after heating in a salt bath furnace at l180-12l0 C. and subjected after the hardening to two tempering treatments for one hour each at 560-590 C.
• a process for the production of cast high-speed steel tools consisting essentially of 9.5 tungsten, 4.3% chromium, 5.2% molybdenum, 3.5% vanadium, 10.5% cobalt and 1.3% carbon, the balance essentially of iron in which the cast tools are diffusion annealed for one to eight hours at 10501200 C., hardened by quenching in oil after heating in a salt bath furnace at 11801210 C. and subjected after the hardening to two tempering treatments for one hour each at 560590 C.
• a process for the production of cast high-speed steel tools consisting essentially of 18.5% tungsten, 4.3% chromium, 1% vanadium, 0.78% carbon, the balance essentially of iron in which the cast tools are diffusion annealed for one to eight hours at 1050-1200 C., hardened by quenching in oil after heating in a salt bath furnace at 12401270 C., and subjected after the hardening to two tempering treatments for one hour each at 550580 C.
• a process for the production of cast high-speed steel tools consisting essentially of 6.5% tungsten, 5% molybdenum, 4.3% chromium, 2% vanadium, 0.86- 0.90% carbon, the balance essentially of iron in which the cast tools are difiusion annealed for one to eight hours at 1050-1200 C., hardened by quenching in oil after heating in a salt bath furnace at 1190-1220 C., and subjected after the hardening to two tempering treatments for one hour each at 540570 C.
• a process for the production of cast high-speed steel tools consisting essentially of 6.5% tungsten, 5% molybdenum, 4.3% chromium, 2% vanadium and 0.85% carbon, the balance essentially of iron in which the cast tools are diffusion annealed for one to eight hours at 10501200 C., hardened by quenching in oil after heating in a salt bath furnace at 1200-1230 C., and subjected after the hardening to two tempering treatments for one hour each at 550-5 C.
• a process for the production of high-speed steel tools which have been cast into molds by the precision investment casting process, said steel consisting essentially of at least about 1.4% carbon, substantially 12% tungsten, 4% chromium, 4% vanadium, 5% cobalt, the balance essentially iron, comprising preheating said tool as cast to 850 C., then subjecting the tool to diffusion annealing for 1 to 8 hours at 1050" C. to 1200 C. and then tempering for 1 hour at 570 C.

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

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Cited By (8)

Citations (4)

• 1957
  • 1957-08-02 AT AT512157A patent/AT208902B/de active
• 1958
  • 1958-07-28 CH CH6232558A patent/CH412953A/de unknown
• 1964
  • 1964-04-06 US US357732A patent/US3211593A/en not_active Expired - Lifetime

Patent Citations (4)

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