Classifications

• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
  • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working

Definitions

• the invention is based on a method for producing a semifinished product or a finished part according to the preamble of claim 1.
• Ductility of the workpiece to be deformed leaves something to be desired and the necessary deformation forces and the deformation energy are relatively high.
• Superplastic forming relies on an ultra-fine grain of the blank, which can only be achieved with certain alloy additives and complex thermomechanical processes. Certain materials do not show any superplasticity at all, so that due to these requirements with regard to the structure of the structure, the corresponding material limits are encountered again. There is therefore a great need to expand the possibilities of hot-forming metallic materials in general by refining and broadening the processes and to extend them to as many materials as possible.
• the invention is based on the object of specifying a hot molding process for metallic materials which, with great simplicity, allows the production of semifinished or finished parts in as few work steps as possible and, thanks to good mold filling capacity, allows the design limits to be expanded.
• the process is said to possibly work on a variety of plants Substances may be applicable.
• the main idea of the invention is to form the material as close as possible to below the solidus temperature, but to avoid local liquefaction in the best possible way. With this measure, the yield stress (deformation resistance) of the material is reduced considerably, so that optimum mold filling capacity is achieved.
• the figure shows the working diagram of the method in the form of a time / temperature function.
• the abscissa represents the time axis, the ordinate the temperature axis. With the horizontal on the
• Level 1 indicates the solidus temperature T sol of the material (alloy) to be deformed, which must not be reached during the entire work process under any circumstances. Otherwise local melting would occur and the connection and controlled structure of the workpiece would be lost.
• 2 is the maximum temperature which - mostly at the end of the shaping - can be reached by the workpiece and tool at the same time. Depending on the alloy and type of workpiece, it must always remain below 1 (T sol ) by a certain amount.
• 3 represents the comogenization system temperature of the workpiece, for which the same applies as for temperature 2, so that subsequent melting during the forming process can be avoided with certainty.
• 4 is the course of the workpiece temperature over time until the end of the shaping. This operation breaks down into the preheating phase 8 and the forming phase 9.
• 5 represents the course of the workpiece temperature during normal cooling to room temperature. 6 is the analogous course after shaping in the event that the latter is directly subjected to further additional heat treatment (e.g.
• Embodiment I Die pressing of a radial compressor wheel made of an Al-Cu-Mg-Ni alloy.
• a radial compressor wheel with a diameter of 180 mm was produced in one operation by isothermal high-temperature pressing from a disc-shaped cylindrical blank.
• the aluminum alloy used complied with US AA standard 2618 and had the following composition:
• Si 0.10 - 0.25% by weight
• Ni 0.9-1.2% by weight
• Zn 0.10% by weight
• a disc in the form of a rod section was used as the starting material.
• the rod itself was made from a section of a larger diameter press stud produced by extrusion by extrusion.
• workpieces produced by open-die forging can also be used as preforms.
• the shape of the compressor wheel to be produced had 18 radially standing blades, slightly curved on the circumference in the tangential direction, of approximately 30 mm depth, which had a wall thickness of approximately 4 mm at the base and one of approximately 2 mm at the head.
• the disk-shaped wheel body had an axial wall thickness of approx. 6 mm on the circumference.
• the starting material was subjected to a homogenization annealing at a temperature of 520 ° C. for 20 hours before the shaping. This measure serves to avoid local melting or local pore formation when the maximum temperature is subsequently passed during the shaping process.
• the latter was carried out as an isothermal high-temperature die press on a specially designed hydraulic press equipped with inductive workpiece and tool heating.
• the press was set up for low stamp speeds of 0.05 - 5 mm / s, which could be changed as desired during the pressing. Furthermore, the pressing force could also be kept constant over a longer predetermined period of time after a predetermined limit value had been reached.
• the table and stamp were provided with a cooling device.
• the inductive heating system consisted of an induction coil for heating the workpiece blank as well as the tools (dies) made of hot-work steel. Precise temperature control and temperature control was ensured via thermocouples in the tool and via buttons on the workpiece blank. A specially designed device was used to transport the workpiece into the heating zone or into the area of the tool, as well as to eject it from the tool after it had been formed and transported to storage.
• the workpiece blank in the form of a disc was first continuously heated to a temperature of 480 ⁇ + 10 ⁇ C by inserting it into the associated induction coil. Then the blank was ⁇ out in the 480 - 520 ⁇ C heated
• the pressing speed was set to an average value of approx. 0.5 - 1 mm / s.
• the pressing force rose only slightly (from 0 to approx. 500 kN).
• the blades were then shaped in a second phase, the punch speed being reduced to 0.05-0.1 mm / s and the pressing force increasing steadily until it reached its maximum (approx. 3000 kN).
• the pressing force was now kept constant in order to completely fill the mold during this third phase, which lasted about 5-10 minutes.
• the pressing time for such a compressor wheel was approx. 10-20 min. the mean pressing pressure was approximately 120 MPa.
• the solidus temperature is at 549 ° C, the solution treatment at 530 ⁇ ⁇ C.
• the solution treatment at 530 ⁇ ⁇ C.
• At 520 C exists in this alloy still undissolved intermetallic compound FeNiAl 9 as a separate phase. It prevents uncontrolled grain growth during high temperature shaping.
• the deformation temperature of 480 ⁇ - 520 ⁇ C was optimally chosen in this regard and local pore formation due to melting was also not to be feared.
• the forming is according to the conventional forging technology, which for the aforementioned aluminum alloy in the temperature range of about 410 - 450 ° C is carried out, Wesent lent favorable.
• the pressures here are between 200 and 500 MPa, which requires heavier and stronger presses.
• the mold filling capacity is significantly poorer, so that the blades do not reach the target dimension (rib wall thickness 2 - 4 mm) by far and one with rib thicknesses of approx. 8 - 10 mm in the first
• Embodiment II Die pressing of a turbine blade made of a precipitation-hardenable nickel-based superalloy.
• Nimonic-80A had the following composition:
• a section from a rolled bar was used as the starting material.
• the primary material was first annealed under protective gas at a temperature of 1080 o C for 8 hours and then quenched in water.
• the hydraulic press provided for carrying out the operation was constructed similarly to that described in Example I. It had an adjustment range for the stamp speed of 0.05 - 25 mm / s.
• it was encapsulated in such a way that operation under protective gas or vacuum was possible. Dies were used as tool from the well-known molybdenum alloy TZM, which allow operating temperatures up to over 1200 ⁇ C.
• the inductive heating was designed in the same way as that in example I.
• lock chambers which enabled the transition between the press room and the outside world.
• the blank was first heated to a temperature of 1100 o + 20 o C in the associated induction coil then placed in the TZM die heated to 1150 ° - 1200 ° C.
• the stamp was then pressed against the lower half of the die at a pressing speed of approx. 4 mm / s (phase I). After the beginning of the pressing force rose, it was then deformed at a pressing speed of approx. 0.1 mm / s for the purpose of filling the burr section (phase II). After reaching the maximum force, this value was reached for about 5 minutes until the mold was finally filled. kept constant (phase III). Depending on the shape and material, this phase can last approx. 1 - 10 min.
• the total pressing time for such a turbine blade can be approximately 2-15 minutes.
• the mean pressing pressure in the present case reached approximately 200 MPa.
• the present nickel-based superalloy has a solidus temperature of approx. 1360 o C and a solution annealing temperature of approx. 1080 o C. In the temperature range of 1150 ⁇ - 1200 C ⁇ what a sufficiently large distance from the solidus to prevent incipient melting speaks ent, there are still unresolved metal carbides in finely divided form. These prevent uncontrolled grain growth during high-temperature deformation, which could also be determined by comparing metallographic micrographs.
• a turbine blade of 200 mm in length and 50 mm in width was produced in one operation by isothermal high-temperature presses from a rod section.
• the iron alloy used had the following composition:
• Example II A section of an extruded rod was used as the starting material.
• the alloy itself was produced in a known manner by powder metallurgy by mechanical alloying and subsequent compression by extrusion.
• the blank was first homogenized at a temperature of 1150 ° C. for 15 minutes and cooled again to room temperature.
• the further process steps were carried out in a manner analogous to that described in Example II.
• the submicroscopic form and distribution of the oxidic dispersoids Y 2 O 3 and TiO 2 are thermally stable up to over 1200 ° C and reliably prevent uncontrolled grain growth during the operations.
• a finished part made in this way from a dispersion alloy is characterized by maximum density, ie absolute freedom from pores compared to the conventional type of workpiece directly produced by powder metallurgy (pressing + sintering, hot isostatic pressing).
• a round rod of 5 mm in diameter was extruded from a press bolt by isothermal high-temperature extrusion
• the shape memory alloy used had the following composition:
• a precompacted ingot produced by mechanical alloying from a Cu / Ni pre-alloy and aluminum with Al 2 O 3 was used as the starting material, which served as a press bolt.
• the press bolt was first homogenized at 950 ° C for 1 h and cooled again to room temperature. Thereupon it was heated to a temperature of 850 ° C. and at a temperature of 850 ° to 950 ° C. by means of a matrix made of a nickel-based alloy (trade name IN-100) to form a strand of 5 mm in diameter.
• the presence of the Al 2 O 3 dispersoid in an ultrafine distribution prevents inadmissible grain growth during the pressing process.
• T sol solidus air temperature in degrees Kelvin
• the workpiece Before shaping, the workpiece is advantageously homogenized for 0.1 to 100 h at a temperature which corresponds to the highest effective deformation temperature, in order to avoid local melting and pore formation, and is cooled again to room temperature.
• the cooling after shaping can also be done by quenching to room temperature in water or oil. Quenching, similar to thermal hardening, can also be carried out to a temperature above room temperature in a metal or salt bath with subsequent aging.
• hot forming can be drop forging, hot pressing, hot extrusion or hot extrusion.
• the hot forming should be carried out in a temperature range in which, in addition to a first phase as the main structural component, there is also a second phase which inhibits grain growth at least during the entire shaping time.
• the latter can preferably consist, for example, of an oxidic dispersoid, such as Y 2 O 3 , TiO 2 , Al 2 O 3 etc., or of an ordinary oxide or of a carbide.
• an oxidic dispersoid such as Y 2 O 3 , TiO 2 , Al 2 O 3 etc.
• the method can also be applied to heat-resistant, rustproof ferritic, ferritic-austenitic and austenitic steels, in particular oxide-dispersion-hardened steels.
• the raw material can also be in the raw state as a porous sintered body or as a green, cold-pressed body made of a sintered material, which is compressed, sintered and converted into the intended shape at the same time during the shaping process.

Landscapes

• Chemical & Material Sciences (AREA)
• Mechanical Engineering (AREA)
• Thermal Sciences (AREA)
• Crystallography & Structural Chemistry (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Physics & Mathematics (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Forging (AREA)
• Adornments (AREA)
• Powder Metallurgy (AREA)
• Heat Treatment Of Steel (AREA)
• Moulds For Moulding Plastics Or The Like (AREA)

Priority Applications (1)

Applications Claiming Priority (2)

Publications (1)

Family

ID=4272115

Family Applications (1)

Country Status (8)

Citations (5)

• 1982
  • 1982-06-22 BR BR8207730A patent/BR8207730A/pt unknown
  • 1982-06-22 JP JP57501887A patent/JPS58501041A/ja active Granted
  • 1982-06-22 WO PCT/CH1982/000082 patent/WO1983000168A1/de not_active Ceased
  • 1982-06-23 EP EP82200780A patent/EP0069421B1/de not_active Expired
  • 1982-06-23 DE DE8282200780T patent/DE3270846D1/de not_active Expired
  • 1982-06-23 AT AT82200780T patent/ATE19531T1/de not_active IP Right Cessation
  • 1982-06-25 PL PL23715082A patent/PL237150A1/xx unknown
  • 1982-06-26 KR KR8202862A patent/KR890003976B1/ko not_active Expired

Patent Citations (5)

Also Published As

Similar Documents

Legal Events