Classifications

• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C33/00—Making ferrous alloys
  • C22C33/02—Making ferrous alloys by powder metallurgy
  • C22C33/0257—Making ferrous alloys by powder metallurgy characterised by the range of the alloying elements
  • C22C33/0264—Making ferrous alloys by powder metallurgy characterised by the range of the alloying elements the maximum content of each alloying element not exceeding 5%
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
  • B22F3/12—Both compacting and sintering
  • B22F3/1208—Containers or coating used therefor
  • B22F3/1258—Container manufacturing
  • B22F3/1266—Container manufacturing by coating or sealing the surface of the preformed article, e.g. by melting
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
  • B22F3/12—Both compacting and sintering
  • B22F3/14—Both compacting and sintering simultaneously
  • B22F3/15—Hot isostatic pressing
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
  • B22F3/12—Both compacting and sintering
  • B22F3/16—Both compacting and sintering in successive or repeated steps
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C33/00—Making ferrous alloys
  • C22C33/02—Making ferrous alloys by powder metallurgy
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
  • B22F3/12—Both compacting and sintering
  • B22F3/14—Both compacting and sintering simultaneously
  • B22F2003/145—Both compacting and sintering simultaneously by warm compacting, below debindering temperature
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F2998/00—Supplementary information concerning processes or compositions relating to powder metallurgy
  • B22F2998/10—Processes characterised by the sequence of their steps
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F2999/00—Aspects linked to processes or compositions used in powder metallurgy

Definitions

• the invention relates to a method for producing a high-strength and wear-resistant Moldings with low dimensional variation made of low-alloy Steel powder, in which the steel powder is pressed with additives, sintered and the sintered molding is subjected to a post-heat treatment.
• a method is known in which a high-speed steel powder is used for wear-resistant applications.
• the alloying elements are alloyed into the iron, with quality S 6-5-2 these are mainly the elements 4 mass% Cr, 5 mass% Mo, 6 mass% W and 2 mass% V. Due to this Alloy technology is a poor compressibility of the steel powder, which only allows an initial density (green density) of about 6.4 g / cm 3 at Mpa. This means that th To accept density of> 99% high vibrations (10 to 12%), which is synonymous with loss of dimensional accuracy.
• This process requires expensive raw materials on the one hand and on the other hand always expensive mechanical operations.
• This object is achieved according to the invention in that the alloyed with chromium, molybdenum, vanadium and steel powder mixed with carbon are pressed in a hot pressing process to give green compacts or powder compacts to a uniform initial density of ⁇ 7.2 g / cm 3 , in that the pressed components Green compacts or powder compacts are sintered to achieve a closed porosity at a temperature of 1150 ° C to 1300 ° C and that the sintered parts in a final hot isotopic pressing process (HIP process) are densified to densities> 99% of the theoretical density.
• HIP process hot isotopic pressing process
• the low-alloy steel powder provided with chromium Cr and other wear-increasing admixtures such as molybdenum Mo, vanadium V and carbon C can already be made into a green compact with a higher uniform density of ⁇ 7.2 g / cm 3 in the hot pressing process.
• a closed porosity is achieved in the subsequent sintering process.
• post-compaction up to a density> 99% of the theoretical density is achieved and the sintering shrinkage is significantly reduced, which results in a small dimensional deviation of the sintered and hipped molded part.
• the process steps required for the process are in material processing usual and do not require any particularly complex devices for Implementation of the method so that the molded parts can also be produced inexpensively can be.
• the molded parts produced have increased dimensional accuracy, so that the further processing effort to achieve a predetermined Dimensional accuracy can be greatly reduced.
• the desired increased initial density of the hot pressed green parts is thereby achieved that the hot pressing process at a temperature of 130 ° C to 150 ° C and a pressure> 750 MPa is carried out.
• the sintering process is carried out until a closed porosity is reached and the final HIP process to further increase the density > 99% of the theoretical density comprises heat pressure treatment in one Atmosphere with inert gas (e.g. argon) at a temperature of around 980 ° C and a pressure of about 1500 bar.
• inert gas e.g. argon
• the sintered and hipped molded parts can be mechanically Machining or cold forming can be brought to a narrower dimensional tolerance.
• the post-processing effort is very low because the size of the Molded parts after the HIP process only a fraction of that with the achievable dimension of the required known method mentioned at the outset Dimension of the molded parts is.
• a final surface hardening can be carried out with a heat treatment if there is an increase in wear resistance or fatigue strength is placed on the molded parts.
• the heat treatment can Tempering, case hardening or nitriding.
• the hot pressed green compacts are in the temperature range from 1150 ° C to 1300 ° C sintered ⁇ to get a closed porosity.
• the closed one Porosity of the sintered parts is one for the subsequent HIP process imperative.
• the hipped sintered parts have a small sinter shrinkage and a smaller dimension than the required nominal dimension, as the table below shows in comparison with a molded part made from high-speed steel according to the prior art.
• Material composition Sinter shrinkage in% Achieved th. Density in% achievable tolerance class Dimension at nominal size 18-30 mm Fe4Cr5Mo6W2V1C 10 to 12 > 99 IT12 210 ⁇ m Fe1Cr0.5Mo0.2V ⁇ 1 > 99 IT10 84 ⁇ m
• the sintering shrinkage can be reduced by an order of magnitude decrease and the dimension from the nominal dimension is for a nominal dimension range from 18 mm to 30 mm only about a third, which is a significant reduction post-processing to achieve the required nominal tolerance affects.
• the achievable tolerance class IT10 is two steps below the tolerance class IT12 known procedures.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Chemical & Material Sciences (AREA)
• Manufacturing & Machinery (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Powder Metallurgy (AREA)

Applications Claiming Priority (2)

Publications (2)

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Cited By (1)

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• 1997
  • 1997-11-27 DE DE1997152505 patent/DE19752505C1/de not_active Expired - Fee Related
• 1998
  • 1998-11-11 EP EP98121445A patent/EP0919635A3/fr not_active Withdrawn

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