KR20230095099A - Austenitic alloys, blanks, parts and methods of heat treatment of austenite - Google Patents

Abstract

The present invention relates to alloys, blanks, parts, and methods made of austenite, wherein the new alloy allows austenite to be used at high temperatures and new heat treatments can be applied.

Description

Austenitic alloys, blanks, parts and methods of heat treatment of austenite

The present invention relates to austenitic alloys, particularly blanks produced by forging and suitable for parts in high temperature applications, and methods.

Depending on the application conditions, forged discs for turbines, in particular rotors of gas turbines, have hitherto been manufactured from various forged steels. That is, NiCrMoV is used for compressor disks, or CrMoWVNbN is used for turbine disks. Application conditions and design requirements are decisive for the selection of forging materials. When selecting a forging material, a balance of strength and toughness must always be ensured to comply with design requirements.

There are currently no solutions using austenitic steels for higher service temperatures.

A switch to nickel disks is currently being considered. Using this disk, it is said that operating temperatures in excess of 923K are possible.

Unfortunately, such components have the following drawbacks:

- Very high cost compared to steel discs,

- It takes longer to process in manufacturing.

The object of the present invention is therefore to solve the above-mentioned problem.

The problem is solved by an alloy according to claim 1 , a blank according to claim 2 , a component according to claim 3 and a method according to claim 9 .

The dependent claims enumerate further advantageous measures which can be combined with one another as desired.

A286 standard alloy has long been evaluated for use in blades in steam turbines. The A286 standard material itself has been found to have potential for use up to 923K. Unfortunately, the intensity is too low.

More recent considerations suggest that the required strength is possible through adaptation to the chemistry, in particular through an increase in the manganese fraction (Mn), titanium content (Ti) and/or molybdenum content and/or decrease in the silicon fraction (Si). show that it is

With reference to strength/toughness balance and notch sensitivity, different heat treatments are performed using the blanks.

According to the invention the following heat treatment (HT) is carried out:

Annealing [AN] and various aging [AG] as heat treatment for austenite in general and for the alloy according to the invention in particular:

number AN Primary AG 2nd AG tertiary AG

One 1253K 993K -- --

2 1253K 993K 953K --

3 1253K 1033K 993K --

4 1253K 993K 1033K 953K

5 1253K 1033K 993K 953K

6 1293K 1033K 923K --

As heat treatment the following variants are available:

1253K에서 용해되고 993K에서 단 1회 에이징된 용액;

solution dissolved at 1253 K and aged only once at 993 K;

제2 변형의 경우, 제1 변형에 기반하여 추가로 953K에서 2차 에이징 시행;

In the case of the second modification, second aging is additionally performed at 953K based on the first modification;

제3 변형의 경우, 1253K에서 1차 용체화 어닐링(solution annealing), 1033K에서 1차 에이징, 그리고 993K에서 2차 에이징 시행;

For the third variant, 1st solution annealing at 1253K, 1st aging at 1033K, and 2nd aging at 993K;

제4 변형의 경우, 1253K에서 1차 용체화 어닐링, 993K에서 1차 에이징, 1033K에서 2차 에이징, 그리고 953KC에서 3차 에이징 시행;

For the fourth variant, 1st solution heat annealing at 1253K, 1st aging at 993K, 2nd aging at 1033K, and 3rd aging at 953KC;

제5 변형의 경우, 1253K에서 1차 용체화 어닐링, 1033K에서 1차 에이징, 993K에서 2차 에이징, 그리고 953K에서 3차 에이징 시행;

For the fifth variant, 1st solution heat annealing at 1253K, 1st aging at 1033K, 2nd aging at 993K, and 3rd aging at 953K;

제6 변형의 경우, 1293K에서 1차 용체화 어닐링, 1033K에서 1차 에이징, 923K에서 2차 에이징 시행;

For the sixth variant, 1st solution heat annealing at 1293K, 1st aging at 1033K, 2nd aging at 923K;

As well as use as forged disks in gas turbines, other uses are conceivable such as:

- gas turbine blades

- gas turbine ring

- steam turbine blades or

- Steam turbine forged parts.

Advantages include:

- Expansion of the use area of inexpensive iron-based alloys compared to expensive nickel-based materials

- Faster machinability of iron-based rotor parts compared to nickel-based materials

- Most of the experience from the construction, manufacturing and production of high-alloy iron-based alloys can be employed. This is helpful for any probabilistic approach.

- Since the application temperature can be increased, the output and performance of the machine can be increased without external cooling.

Austenitic steel has the following composition:

Alloys comprising (in weight percent), in particular consisting of, the following elements:

Carbon (C): 0.03% to 0.08%

Silicon (Si) 0.20% to 0.40%

Manganese (Mn) 1.60% to 2.00%

Chromium (Cr) 13.5% to 16.0%

Molybdenum (Mo) 2.00% to 2.50%

Nickel (Ni) 24.0% to 27.0%

Vanadium (V) 0.25% to 0.35%

Aluminum (Al) 0.40% to 0.60%

Titanium (Ti) 2.00% to 2.30%

Niobium (Nb) 1.00% to 1.20%

Tungsten (W) 1.80% to 2.20%

Boron (B) 0.004% to 0.006%

optionally

Phosphorus (P) 0.025% or less

Sulfur (S) 0.015% or less

Arsenic (As) 0.008% or less

Tin (Sn) 0.008% or less

Antimony (Sb) 0.002% or less

Nitrogen (N) 0.005% or less

remaining iron.

From these alloys blanks are cast according to the prior art and forged according to the prior art.

Claims (17)

is an alloy,
The following elements (in weight percent):
Carbon (C) 0.02% to 0.08%
Silicon (Si) 0.20% to 0.40%
Manganese (Mn) 1.60% to 2.00%
Chromium (Cr) 13.5% to 16.0%
Molybdenum (Mo) 2.00% to 2.50%
Nickel (Ni) 24.0% to 27.0%
Vanadium (V) 0.25% to 0.35%
Aluminum (Al) 0.40% to 0.60%
Titanium (Ti) 2.00% to 2.50%
Niobium (Nb) 1.00% to 1.20%
Tungsten (W) 1.80% to 2.20%
Boron (B) 0.004% to 0.006%
optionally:
Arsenic (As) 0.008% or less
Tin (Sn) 0.008% or less
Antimony (Sb) 0.002% or less
Nitrogen (N) 0.005% or less
Phosphorus (P) 0.025% or less
Sulfur (S) 0.015% or less
residual iron
and the inevitable impurity
An alloy comprising, in particular composed of, these elements. As blanks, especially forgings,
It includes iron-based alloys, which iron-based alloys (in weight percent):
Carbon (C): 0.02% to 0.08%
Silicon (Si) 0.20% to 0.40%
Manganese (Mn) 1.60% to 2.00%
Chromium (Cr) 13.5% to 16.0%
Molybdenum (Mo) 2.00% to 2.50%
Nickel (Ni) 24.0% to 27.0%
Vanadium (V) 0.25% to 0.35%
Aluminum (Al) 0.40% to 0.60%
Titanium (Ti) 2.00% to 2.50%
Niobium (Nb) 1.00% to 1.20%
Tungsten (W) 1.80% to 2.20%
Boron (B) 0.004% to 0.006%
optionally:
Arsenic (As) 0.008% or less
Tin (Sn) 0.008% or less
Antimony (Sb) 0.002% or less
Nitrogen (N) 0.005% or less
Phosphorus (P) 0.025% or less
Sulfur (S) 0.015% or less
and the inevitable impurity
Including, blank. is a part,
It includes iron-based alloys, which iron-based alloys (in weight percent):
Carbon (C): 0.02% to 0.08%
Silicon (Si) 0.20% to 0.40%
Manganese (Mn) 1.60% to 2.00%
Chromium (Cr) 13.5% to 16.0%
Molybdenum (Mo) 2.00% to 2.50%
Nickel (Ni) 24.0% to 27.0%
Vanadium (V) 0.25% to 0.35%
Aluminum (Al) 0.40% to 0.60%
Titanium (Ti) 2.00% to 2.50%
Niobium (Nb) 1.00% to 1.20%
Tungsten (W) 1.80% to 2.20%
Boron (B) 0.004% to 0.006%
optionally:
Arsenic (As) 0.008% or less
Tin (Sn) 0.008% or less
Antimony (Sb) 0.002% or less
Nitrogen (N) 0.005% or less
Phosphorus (P) 0.025% or less
Sulfur (S) 0.015% or less
and the inevitable impurity
Including, parts. 4. The alloy, blank or part according to claim 1, 2 or 3, comprising 0.02% by weight of carbon (C). 4. The alloy, blank or part according to claim 1, 2 or 3 comprising between 0.03% and 0.08% carbon (C) by weight. 4. The alloy, blank or component according to any one or more of claims 1, 2 or 3, comprising 2.5% by weight of titanium (Ti). The alloy, blank, or alloy of claim 1 , 2 , 3 , 4 , or 5 comprising from 2.0% to 2.3% by weight of titanium (Ti). part According to any one or a plurality of claims 3, 4, 5, 6 or 7,
In particular, each gas turbine
a rotor disk; or
turbine blades; or
constitute a turbine ring, or
steam turbine blades or
Constituting steam turbine forged parts,
In particular, a component heat treated according to any one or more of claims 9 to 14. Process for heat treatment of austenite, in particular blanks or parts according to any one or more of claims 2, 3, 4, 5, 6, 7 or 8,
A solution heat annealing is performed at at least 1253 K,
1st aging is performed at least at 993K,
optionally
At least at 923K,
In particular, secondary aging is performed at a temperature at least 30K lower than the temperature of the first aging,
optionally
At least 953 K, at least 30 K lower than the temperature of the second aging,
In particular, a heat treatment method in which tertiary aging is performed at 953 K. According to claim 9,
solution heat annealing at 1253 K;
primary aging at least at 993 K, in particular at 993 K;
optionally
A heat treatment method comprising secondary and/or tertiary aging. According to claim 9,
solution heat annealing at 1253 K;
primary aging at least at 1033 K, especially at 1033 K;
optionally
A heat treatment method comprising secondary and/or tertiary aging. According to claim 9,
solution heat annealing at 1293 K;
primary aging at least at 1033 K, especially at 1033 K;
optionally
A heat treatment method comprising secondary and/or tertiary aging. According to any one or a plurality of claims 9, 10, 11 or 12,
solution heat annealing at least 1253 K;
1st aging at least 993K,
secondary aging at least at 923 K, in particular at 923 K;
A method of heat treatment, optionally including tertiary aging. According to any one or a plurality of claims 9, 10, 11 or 12,
solution heat annealing at least 1253 K;
1st aging at least 993K,
Secondary aging at least 923 K,
optionally comprising tertiary aging at 953 K. According to any one or a plurality of claims 9, 10, 11, 12, 13 or 14,
solution heat annealing at least 1253 K;
A heat treatment method comprising primary aging at at least 993 K. According to any one or a plurality of claims 9, 10, 11, 12, 13 or 14,
solution heat annealing at least 1253 K;
1st aging at least 993K,
A heat treatment method comprising secondary aging at at least 923K. According to any one or a plurality of claims 9, 10, 11, 12, 13 or 14,
solution heat annealing at least 1253 K;
1st aging at least 993K,
Secondary aging at least 923 K,
and tertiary aging at at least 953K.