Production method for ring-rolled material of Fe—Ni-based superalloy

Patent metadata

Field	Value
Publication number	US-12594593-B2
Application number	US-201917276346-A
Country	US
Kind code	B2
Filing date	Sep 19, 2019
Priority date	Sep 19, 2018
Publication date	Apr 7, 2026
Grant date	Apr 7, 2026

Abstract

A method for producing a ring-rolled material of an Fe—Ni based superalloy, which has a high circularity, can inhibit AGG, and can inhibit grain growth. A method for producing a ring-rolled material of an Fe—Ni based superalloy having a composition of an Alloy 718 comprises: a finishing ring rolling step of heating a ring-shaped material for ring rolling having the composition, in a temperature range of 900° C. to 980° C., and performing finishing ring rolling; and a circularity correcting step of correcting an ellipticalness of the ring-rolled material that has been rolled in the finishing ring rolling step, while expanding a diameter of the ring-rolled material by using a ring expander including a pipe-expanding cone and a pipe-expanding die, wherein the ring-rolled material that has been rolled in the finishing ring rolling step is subjected to circularity correction without being reheated or after having been heated to up to 960° C.

First claim

The invention claimed is:

1 . A method for producing a ring-rolled material of an Fe—Ni based superalloy having a composition including, by mass %, up to 0.08% of C, 50.0 to 55.0% of Ni, 17.0 to 21.0% of Cr, 2.8 to 3.3% of Mo, 0.20 to 0.80% of Al, 0.65 to 1.15% of Ti, 4.75 to 5.50% of Nb+Ta, up to 0.006% of B, and the balance of Fe with inevitable impurities, using ring rolling, the method comprising:
a finishing ring rolling step, as a final step of the ring rolling, of heating a ring-shaped material for ring rolling to a temperature range of 900 to 970° C. and then maintaining the ring-shaped material for ring rolling in a temperature range of 900 to 970° C. while expanding a diameter of the ring-shaped material for ring rolling and also pressing the ring-shaped material for ring rolling in an axial direction thereof, by using a ring rolling mill having a pair of rolling rolls including a main roll and a mandrel roll, and a pair of axial rolls to inhibit recrystallization in the material for ring rolling and to obtain a ring-shaped ring-rolled material having an unrecrystallized or partially recrystallized structure and storing sufficient strain for avoiding an occurrence of abnormal grain growth (AGG) during hot forging after a circularity correcting step;
a circularity correcting step of improving a circularity of a the ring-shaped ring-rolled material by expanding a diameter of the ring-shaped ring-rolled material by using a ring expander including a pipe-expanding cone and a pipe-expanding die to press the pipe-expanding die against an inner diameter side of the ring-shaped ring-rolled material, the circularity being determined by (D MAX −D MIN )/2 [mm], wherein D MAX is a maximum value of outer diameters of the ring-shaped ring-rolled material after the circularity correcting step, and D MIN is a minimum value of the outer diameter of the ring-shaped ring-rolled material after the circularity correcting step; and
an intermediate ring rolling step, as a pre-step of the finishing ring rolling step, of heating the material for ring rolling to a temperature range of higher than 980° C. and up to 1010° C., and expanding a diameter of the material for ring rolling that has been heated at the temperature range and also pressing the material for ring rolling in an axial direction thereof by using a ring rolling mill having a pair of rolling rolls including a main roll and a mandrel roll, and a pair of axial rolls to have a fine-grained structure in the material for ring rolling by promoting recrystallization,
wherein the ring-shaped ring-rolled material that has been rolled in the finishing ring rolling step is subjected to the circularity correcting step in a temperature range of 800 to 850° C. without being reheated.

2 . The method for producing a ring-rolled material of an Fe—Ni based superalloy according to claim 1 , further comprising optimizing a microstructure in a circularity-corrected material after the circularity correcting step by heating the circularity-corrected material to a temperature range of 980 to 1010° C. before hot forging the circularity-corrected material.

3 . A method for producing a ring-rolled material of an Fe—Ni based superalloy having a composition including, by mass %, up to 0.08% of C, 50.0 to 55.0% of Ni, 17.0 to 21.0% of Cr, 2.8 to 3.3% of Mo, 0.20 to 0.80% of Al, 0.65 to 1.15% of Ti, 4.75 to 5.50% of Nb+Ta, up to 0.006% of B, and the balance of Fe with inevitable impurities, using ring rolling, the method comprising:
a finishing ring rolling step, as a final step of the ring rolling, of heating a ring-shaped material for ring rolling to a temperature range of 900 to 970° C. and then maintaining the ring-shaped material for ring rolling in a temperature range of 900 to 970° C., while expanding a diameter of the ring-shaped material for ring rolling and also pressing the ring-shaped material for ring rolling in an axial direction thereof, by using a ring rolling mill having a pair of rolling rolls including a main roll and a mandrel roll, and a pair of axial rolls to inhibit recrystallization in the material for ring rolling and to obtain a ring-shaped ring-rolled material having an unrecrystallized or partially recrystallized structure and storing sufficient strain for avoiding an occurrence of abnormal grain growth (AGG) therein during a circularity correcting step described below;
a circularity correcting step of improving a circularity of the ring-shaped ring-rolled material by expanding a diameter of the ring-shaped ring-rolled material by using a ring expander including a pipe-expanding cone and a pipe-expanding die to press the pipe-expanding die against an inner diameter side of the ring-shaped ring-rolled material, the circularity being determined by (D MAX −D MIN )/2 [mm], wherein D MAX is a maximum value of outer diameters of the ring-shaped ring-rolled material after the circularity correcting step, and D MIN is a minimum value of the outer diameter of the ring-shaped ring-rolled material after the circularity correcting step; and
an intermediate ring rolling step, as a pre-step of the finishing ring rolling step, of heating the material for ring rolling to a temperature range of higher than 980° C. and up to 1010° C., and expanding a diameter of the material for ring rolling that has been heated at the temperature range and also pressing the material for ring rolling in an axial direction thereof by using a ring rolling mill having a pair of rolling rolls including a main roll and a mandrel roll, and a pair of axial rolls to have a fine-grained structure in the material for ring rolling by promoting recrystallization,
wherein the ring-shaped ring-rolled material that has been rolled in the finishing ring rolling step is subjected to the circularity correcting step after being reheated in a temperature range of up to 960° C. excluding a temperature range of 600 to 760° C.

4 . The method for producing a ring-rolled material of an Fe—Ni based superalloy according to claim 3 , further comprising optimizing a microstructure in a circularity-corrected material after the circularity correcting step by heating the circularity-corrected material to a temperature range of 980 to 1010° C. before hot forging the circularity-corrected material.

Assignees

• Proterial Ltd

Inventors

• Aoki Chuya
• Fukui Tsuyoshi
• Ohtoyo Daigo
• Fujita Etsuo
• Iwasa Naoyuki
• HIROSAWA Taku

Classifications

• C22F1/10

  of nickel or cobalt or alloys based thereon · CPC title

• C22C19/056

  with the maximum Cr content being at least 10% but less than 20% · CPC title

• B21J1/06

  Heating or cooling methods or arrangements specially adapted for performing forging or pressing operations {(B21J5/063 takes precedence)} · CPC title

• B21H1/06 Primary

  rings of restricted axial length (extending closed shapes of metal bands by simultaneous rolling at two or more zones B21B5/00) · CPC title

• C22C19/055

  with the maximum Cr content being at least 20% but less than 30% · CPC title