JPS59205452A - High strength member for machinery mounted on board submarine searching ship - Google Patents

Abstract

PURPOSE:To provide the titled high strength member having both of high strength and high toughness and low in magnetic permeability, obtained by applying hot processing respectively prescribed in a draft and a finish temp. to an Fe base alloy respectively containing C, Si, Mn, Ni, Cr, Mo and N in a predetermined ratio. CONSTITUTION:Steel containing, on a wt. basis, 0.15% or less C, 0.1-2.0% Si, 7.0-18.0% Mn, 0.5-6.0% Ni, 15.0-26.0% Cr, 0.5-4.0% Mo and 0.2-0.6% N and comprising the remainder of substantially Fe is prepared. Subsequently, hot processing is applied to said steel under such a condition that a draft is 50% or more and a finish temp. is 800-1,000 deg.C. Thus proof-stress at 0.2% is 80kg/mm.<2> or more, a Charpy impact value is 8kgm/cm<2> and magnetic permeability is 1.5% or less and optimum as a high strength member for machinery mounted to a submarine searching ship.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a strength member for equipment mounted on an underwater exploration vessel that has both high strength and high toughness and low magnetic permeability.

In general, an underwater exploration vessel is a vessel that has the mission of detecting obstacles floating on the sea or in the sea using detectors such as radar and ultrasonic waves, and removing the obstacles.
It is an object of the present invention to provide a strong member for equipment mounted on an underwater exploration vessel, which is made of a substantially non-magnetic steel with low magnetic permeability, which has high strength and high toughness comparable to precipitation hardening stainless steel. This is the purpose. That is, the member of the present invention has the following properties.

(c) 0. Flathead proof stress Hgokg/- or more (2) Charpy impact value: g kgm/cm2 or more (3) Magnetic permeability: /, S or less Next, the present invention will be described in detail.

Austenitic stainless steel is commonly used as a non-magnetic steel. However, this steel is usually used as a structural material after being subjected to solution treatment, and materials subjected to such treatment have the disadvantage of low yield strength. In order to improve this point, aging treatment or cold working is mainly performed after solution treatment, but although the former treatment increases the strength, it leads to a significant decrease in impact value; The processing has disadvantages in that the magnetic permeability increases due to cold working, or that cold working is limited due to the shape of the product.

The present inventors have developed HN using precipitation strengthening of chromium phosphide.
Various studies have been conducted on M steel or high manganese austenitic stainless steel using vanadium carbonitride precipitation strengthening, but as the strength increases, the impact value decreases significantly, which is the target. , a 2% yield strength of gokg/- or more and an impact value of g1m/Cm2 or more were not obtained.

Therefore, the inventors of the present invention first published the patent application published in Japanese Patent Application Laid-Open No. ,? ,-//96
/7 and Tokukai Sho! ;3-//As a result of research focusing on high-strength austenitic stainless steels that have a first-class 0.2% yield strength to 60 degrees even in the solution state disclosed at 9 A/g, it was found that these steels have a high strength in the hot worked state. They newly discovered that the material has excellent strength and toughness, and came up with the idea for the member of the present invention.

Next, the present invention will be explained using experimental data.

ls kg steel ingots were produced for the members of the present invention and the comparative materials having the compositions shown in Table 1, and hot forged. A round bar of r 7r (zφ) was used as a test material. Samples were cut from this and subjected to the heat treatment shown in Table 2, and the mechanical properties and magnetic permeability of each were examined.

The results are shown in Table 3.

Table 3: Mechanical properties and magnetic permeability of the members of the present invention and comparative materials Table 3: As shown in Table 3, the members of the present invention have a target of O, 2 proof stress of 0, 2 proof stress or more, Charpy impact value g
kl? m/cm2 or more and magnetic permeability i of 5 or less. Comparative material 33 is N-added) INM steel, comparative material 3'l is precipitation hardening stainless steel, comparative material 3 left is scM
There is no one that satisfies all of the above goals.

Table 7 shows the mechanical properties and magnetic permeability of members of the present invention subjected to conventional solution treatment. In addition, the vulgarization processing conditions are 10! rO°C x 30 min WQ. It can be seen that the θ.J% yield strength and tensile strength of the hot forged specimens shown in Table 3 are significantly lower than those of (1) (C).

Figure 1 shows one of the members of the present invention. This figure shows the relationship between each of the 0.2 coefficient, tensile strength, and impact value, and the finishing temperature of hot working. Note that the pressure F ratio of hot working is 70%. According to the figure, it can be seen that as the finishing temperature increases, the O, flathead yield strength and tensile strength decrease, and the impact value increases.

FIGS. 2 and 3 show the same relationships as in FIG. 1 for the member 7 of the present invention and Koda, respectively.

Similar to the present invention member 1, 0.0% for 2 as the finishing temperature increases. :lTo proof stress and tensile strength decreased and impact value increased.

From Figures 1 to 3, the target 0.2% yield strength go kg/m
It can be seen that in order to satisfy rtf' or more and impact value gkg71L/Crn2 or more, the forging finishing temperature needs to be within the range of goθ to 7000°C.

Table 7 Mechanical properties and magnetic permeability of the members of the present invention in a solution state;
.

20Or −/j treated with pressure F rate 70eI)ty)
Mn-II Ni-2MO-0°2V-0,AN The carbon content was varied between O,OS and 0.37% for steel. , the influence on the 2-inch proof stress and impact value was investigated. The results are shown in Figure 2. From the figure, the 0.2 inch proof stress gradually increases as the carbon content increases, but the impact value increases as the carbon content increases, θ, /! It can be seen that when it exceeds f%, it decreases rapidly.

Next, the reason for limiting the component composition of the member of the present invention will be explained.

Carbon is a strong austenite-forming element and at the same time is an element that significantly enhances the strengthening effect of the austenite matrix. However, if the θ coefficient exceeds 15, a large amount of carbide will precipitate at grain boundaries during hot working, significantly impairing toughness. , carbon must be kept below θ,is%.

Silicon is an effective deoxidizer and an essential component in steelmaking operations.
/ degree is usually required. Furthermore, silicon is a ferrite-forming element and is effective in strengthening the austenite matrix. If the silicon content is more than 2.0%, it will cause scratches and cracks during manufacturing, and it will also produce δ ferrite, which increases magnetic permeability and deteriorates non-magnetism. In addition, during steelmaking work, silicon is
．． / There is no industrial advantage in making it less than excellent. Therefore, the appropriate amount is 0. /~Ko. ocI).

Manganese is an austenite-forming element and significantly increases the solubility of nitrogen. 7. To make the austenite single phase in balance with the Ni content. Since θφ or more is required, the lower limit of manganese is set to 7.0 or more. However, if the manganese content exceeds 7.0 g/g, o'
Limited to the range of A.

Nickel is 0. It is an element that stabilizes austenite together with N and Mn, and in order to obtain a stable austenite phase, a minimum content of O and S% or more is required. If N1 exceeds Ochi or Ochi, the material becomes expensive and its strength decreases, making it unsuitable.
It's not right. Therefore, the nickel content is O, S ~ B. 0
% +/) limited within the range.

Chromium is a basic component for maintaining corrosion resistance, and at the same time acts as a ferrite-forming element.

Also, like manganese, it significantly increases nitrogen solubility.

Chrome/! ; If it is less than 0%, corrosion resistance will be significantly deteriorated. In order to increase nitrogen solubility, the higher the amount of chromium, the better; however, if the content exceeds 24.0%, the structure will not be a single-phase austenite structure but a mixed structure with ferrite, leading to an increase in magnetic permeability and deterioration of hot workability. . Therefore, chromium was set within the range of 75.0 to 26.0.

Molybdenum acts as a ferrite-forming element, and
It is a harmful element to obtain a single phase of stenite.

If the 1-butymolybdenum is within the range of solid solution in the matrix, it is effective for strengthening the matrix, improving toughness, and corrosion resistance, and a coefficient of 0.5 or more is necessary. xi, os
If the molybdenum content exceeds O,S~11, it will generate ferrite and make it difficult to obtain a single phase of austenite.
．． It was limited within the range of 0%.

Like carbon, nitrogen is a strong austenite-forming element, and unlike carbon, it does not precipitate in large amounts as nitrides at the grain boundaries during hot working, making it possible to increase strength without compromising toughness. It is an element that makes 0.2'l
If it is less than r, no improvement in material strength can be expected, so the lower limit is set to 0.
．． 2% or more. Further, if the nitrogen content exceeds O0, blowholes often occur and a sound steel ingot cannot be obtained, so the nitrogen content was limited to a range of 0.2 to 0.4%.

Copper acts as an austenite-forming element, is an effective element for obtaining an austenite single phase, and also strengthens the austenite matrix. It also has the effect of contributing to increasing nitrogen solubility in austenite2 and improving corrosion resistance. o. If it is less than 7%, the effect is small, so 0. /
% or more.

However, if it is contained in an amount exceeding the θ coefficient, grain boundary embrittlement will be promoted at high temperatures, and hot workability will be significantly impaired. Therefore, the copper content is 0.7~T. It was limited to within the range of 0%.

Niobium is a strong carbide-forming element, but also acts as a ferrite-forming element. It becomes fine carbides and nitrides, making the crystal grains finer and improving the strength of the material. o, o3
If the content is less than 0.3%, the effect will be small, and if the content exceeds 0.3%, not only will the cost of the material increase, but the contribution to the strength of the material will be reduced. Therefore, the niobium content is 0003 ~
It was limited to within the range of O03%.

Zirconium, vanadium, titanium, tantalum.

Aluminum is an element that refines crystal grains and greatly contributes to improving material strength. If the content exceeds 0.3%, like niobium, the contribution to the material strength will be small and it will become expensive, so one selected from zirconium, vanadium, titanium, tantalum, and aluminum should be used.
The ratio was set to 0.3 or less.

As described above, the members of the present invention meet the objectives of the present invention as described in the claims, that is, 0.2% proof stress go kg/m- or more, Charpy impact value g ki
It is possible to provide a member that satisfies i' m/crrL2 or more and magnetic permeability/, 1 or less, and it has been newly discovered that the member of the present invention is optimal as a high-strength member for equipment mounted on an underwater exploration vessel.

In addition, since the member of the present invention is a high-strength non-magnetic member, it can be used as a retaining ring for a generator,
It can also be used as a structural material for fusion reactor experimental equipment, superconducting magnet power storage equipment, MHD power generation equipment, superconducting generators, etc.

[Brief explanation of the drawing]

Figures 1 and 2.3 show the hot forging finishing temperature of 7°2'l, proof stress and tensile strength of 0.2'lr, respectively, of the members of the present invention. A diagram showing the relationship with impact value, Figure 4 shows hot working finishing temperature 9
200r-1 treated at 30°C9 rolling reduction rate of 70 inches
5Mn-II Ni-2Mo-0,,2V-0,
FIG. 2 is a diagram showing the relationship between carbon content, O, C proof stress, and impact value of AN steel. Patent applicant Nippon Yakin Kogyo Co., Ltd. Mitsubishi Heavy Industries Co., Ltd. Patent attorney Mura 1) Politics Figure 2 % Jl Kirin 4, (tJjQ(”C) Element amount (・l.)

Claims (1)

[Claims] LO:17. #chi and below, Si:O, /-2. θ%. Mn: 7.0~/g, 0%, Ni: 0°5~
6.0%. Cr; /! ;, 0-21. ．． 0%, Mo:θ. 5
−lI, 0%. N: Contains 0.2 to o, b%, the remainder is substantially Fθ, and is subjected to hot working at a reduction rate of so efo or more, and the finishing temperature of the hot working is goθ°C to lOθO°C. High-strength components for ship-mounted equipment. zcHo, /s% or less, Eli: 0. / ~:
t, 0%. Mn: 7.0~/LO%, Ni: 0. ! r
~6.0%. Or; /! ;, 0-2A, 0%, MO: 0.
! ;-'1.0 Person in charge. N: Contains 0.2 to 0.6%, and the following (a) to (c)
Including one or more types of cabinets selected from the following,
The remaining portion is substantially F's and is subjected to hot working at a cutting rate of Suzuchi or higher, and the finishing temperature of the hot working is f: g000Q −/
A high-strength member for equipment mounted on an underwater exploration vessel that has a temperature of θθO℃. (a) Cu: O, /~ko, Ochi (b) N
b: 0.03 to 0.3 (c) Zr, V, Ta
・One or more types selected from T↓, At, 0.3 cm or more F