JPS59118858A - Rotor for low-temperature turbine - Google Patents

Abstract

PURPOSE:To provide a titled rotor having excellent toughness in a low-temp. region, and high mechanical strength such as yield strength, tensile strength by forming an Fe base alloy consisting of specific compsn. of C, Si, Mn, Ni, Cr, Mo, V and iron. CONSTITUTION:A rotor for a low-temp. turbine formed of an Fe alloy consisting of 0.1-0.25wt% C, <=0.30% Si, 0.20-1.00% Mn, 4.00-5.25% Ni, 0.80-2.00% Cr, 0.20-0.70% Mo, 0.05-0.20% V and consisting of the balance Fe and incidental impurities. Said rotor is suitable for use in a low temp. turbine using particularly low temp. working fluid such as LNG. The rotor formed of the above-mentioned alloy has excellent toughness in a low temp. region as low as about -100 deg.C, has substantial yield strength as rotor and excellent mechanical strength.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a turbine rotor, and more particularly, to a turbine rotor.
The present invention relates to a turbine meter used in a low-temperature turbine that uses a low-temperature working fluid such as NG (liquefied natural gas).

[Technical background of the invention and its problems]

In recent years, low-temperature turbines that use low-temperature working fluids such as LNG/
f14 has been developed, for example, LNG (about -za
A brand of low-temperature turbines that generate electricity by effectively utilizing the cold energy released during the process of vaporizing j”c) using seawater is attracting attention.

These low-temperature turbines operate in the temperature range from room temperature to approximately -100°C, so it is not possible to use the turbine openings used in conventional thermal and nuclear power generation turbines in high-temperature steam atmospheres as they are. , the turbine rotor used in conventional steam turbines is 1100 yen from Muromen.
It has poor toughness in the low temperature range of about 0.degree. C., and the ductile-brittle transition temperature (hereinafter referred to as FATT) is much higher than the rotor's ambient temperature, so there is a risk of brittle fracture h''- occurring.

For example, 3, 2j, which has excellent low-temperature toughness among the mouthpiece materials for steam turbines used in conventional thermal and nuclear power plants,
~Hiroshi, O%Nf-Cr-Mo-V#! Also, FA
TT is -30"C, and there is a possibility of brittle fracture. Therefore, the conditions required for the Talvin meeter used in the low temperature range of -100"C are as follows:
It is required that TT is below -ioo°C. Examples of materials that satisfy this condition include stainless steel and austenitic stainless steel.

However, when the above-mentioned %Nl steel or austenitic stainless steel [,.1] is used as a turbine rotor material, there is a problem that the proof strength required of the rotor material is insufficient. Furthermore, these materials are suitable for large turbine rotors vr
- There are problems such as poor forging properties and poor ability to detect minute material defects in the rotor using ultrasonic waves or the like.

[Purpose of the invention]

The present invention has been made in view of the above points, and -1
It is an object of the present invention to provide a rotor for a low-temperature turbine which has excellent toughness in a low-temperature range of 00"cK and has improved mechanical strength such as yield strength and tensile strength.

[Summary of the invention]

The present inventor has discovered that 3, J
, j ~4', θ% FATT of Nl-Cr-Mo-V steel
We focused on the fact that it has relatively good low-temperature toughness as a rotor material for steam turbines, and researched the conditions to obtain a material that can be sufficiently applied to rotors for low-temperature turbines. As a result, above 3. ．． 23-I1. O
'16 Among the components of Nl-Cr-Mo-V steel, especially Ni
By optimally adjusting the content and C amount, -1
It has been discovered that it is possible to obtain a rotor material for low-temperature turbines that has a FATT of 00°C or less and also has excellent mechanical strength.

The present invention is based on the above findings. That is, the low-temperature turbine rotor of the present invention has a weight ratio of CO, 1 to 0.
0.1%, 5lO03Oq6 or less, Mn 117. ．． 2
(7-/, 00chi, Ni II, 00-!, 21%
, Cr 0JO-2,00%, M.

O,20-0,70%,vo,or ~o,2o%
, and the remainder is Fe and incidental impurities.

[Detailed description of the invention]

The present invention will be explained in more detail below. In the following description, "%" representing the composition is based on weight unless otherwise specified.

The low-temperature turbine rotor of the present invention is made of an Fe-based alloy with a specific composition. The purpose of adding each component in the alloy and the reason for limiting the composition are as follows.

1.C is an essential element for d) to increase the mechanical strength such as tensile strength and proof stress required for the rotor.
The alloy contains 0.23% of θ. Content is 0.
If it is less than 1%, the above effects will be poor, and O, JL
! 081, which decreases toughness when added in excess of the f factor, is added as a deoxidizing agent and should be 0.30% or less. If added in excess of 0.30%, the toughness will decrease 4). Furthermore, if a vacuum carbon deoxidation method is used during turbine rotor manufacture, it is not necessarily necessary to add it.

Mn is added as a desulfurizing agent, and is in the range of 0% to 0%. If it is less than 0.2.0%, the effect of addition cannot be obtained, and if it is added in excess of 1.00%, the effect is saturated.

Ni is an extremely effective element for improving low-temperature toughness, and is added in an amount of '/, 00-j, it%. Hiroshi, θO
It is not possible to obtain a sufficient effect with the addition of Chimishake, and it is preferable to add a large amount to improve toughness.
, J, if added in excess of 3%, the yield strength will decrease.

Cr not only improves hardenability, but also has the effect of improving toughness when added together with Nl.
, to-1,00 chi.

Mo and V are elements necessary to improve hardenability and ensure strength, and Mo is 01.20-0,7
For 0chi and ■, 0.01 to 0.20 q6 is added. Addition of Mo and V above the upper limit reduces toughness.

It is preferable that impurities incidentally included when adding the above components and Fe as the main component be as small as possible.

In order to obtain the turbine rotor of the present invention, first, various raw material metals are mixed and melted in a vacuum or atmosphere, and after deoxidation, a Fe-based alloy molten metal having substantially the above composition is obtained. Next, this is cast, and if necessary, forged to form a material in the shape of a turbine rotor. Next, the turbine rotor of the present invention is obtained by subjecting this material to necessary post-treatments such as heat treatment and surface polishing.

[Examples and comparative examples of the invention]

Seven types of alloy samples each having 5 OKp having the compositions shown in Table 1 below (numbers in the table mean grade) were melted in a vacuum induction melting furnace, forged and stretched into a 50 mm square piece, and the material A specimen with a shape of 1 was obtained.

Comparative example 1 above. ．． 2 and 3 are 3.2j to 11.0, which are used in conventional low-pressure turbine rotors for thermal power generation.
%, corresponds to Nl-Cr-Mo-V steel, and is equivalent to Example No.! , 3 and ≠ are rotor materials of the present invention.

Each of the above material test pieces was subjected to the following heat treatment. First, the tube was heated to 30°C, quenched by cooling at a rate of 100°C per hour, and then tempered at 10°C for V hours. .

The test pieces thus obtained were subjected to tensile tests and F
A 2 mV Hatch Charpy impact test was conducted to determine ATT. The results obtained are shown in Table 1 below. Comparative Example Ko and Example Ko are the actual dimensions of the mouth (diameter approx./m)
This is a prototype turbine rotor manufactured by KlJ.

Table 1 As is clear from the results in Table 2 above, the rotor materials of the present invention (Examples/~≠) have a FATT value of -10θ℃, excellent low-temperature toughness, and yield strength and tensile strength. Regarding the strength, it is almost the same as the conventional material (comparative example/~≠).

〔Effect of the invention〕

As is clear from the results of the examples and comparative examples,
The low-temperature turbine rotor of the present invention has a FATT below -/θθ°C, and has extremely excellent low-temperature toughness. Therefore, there is no risk of brittle fracture even if the device is operated in a low temperature range of -100°C. In addition, the yield strength and tensile strength are almost the same as rotor materials used in conventional steam turbines for thermal power generation, making it suitable for practical use.

Therefore, by using the rotor of the present invention as a rotor for a low-temperature turbine, safety can be further improved.

(1) It becomes possible to design and manufacture a low-temperature turbine plant with improved requirements, which is extremely useful industrially.

Further, the material forming the rotor for a low-temperature turbine of the present invention can be used not only as a rotor for a low-temperature turbine such as an LNG cold energy power generation turbine, but also as a material for other low-temperature industrial machine parts.

Applicant's agent Kiyoshi Inomata

Claims (1)

[Claims] The serious penalty ratio is CO0/-01.2! %, siO
,30% or less. MnO, 20~/, 00%, NlM,
00-3,23%, CrO,ta~2.0
0%, MoO, 20-0.70%, V01
Oj+ ~0. ．． 1. An a-tar for a low-temperature turbine, characterized in that it is formed of an Fe-based alloy containing 20% Fe and the remainder consisting of Fe and incidental impurities.