JPS60211053A - High strength alloy for industrial container - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to nickel-iron-chromium alloys in general, and particularly to high-strength, corrosion-resistant alloys having low work hardening rates with variable age hardening properties. be. This alloy reduces copper pick and drop in fluid streams.

[Background technology]

Power plant operators and boiler manufacturers.

It has long been recognized that regenerative water absorption heating is an effective way to improve the efficiency of steam generators (fossil-fueled and nuclear-fueled).

Essentially, steam is extracted from the steam turbine to preheat the boiler/reactor feedwater before it is introduced into the boiler economizer or directly into the steam generator/reactor.

Of course, the heating of the feed water takes place in the water absorption heater.

Steam is used to heat the feed water inside the feed water heater tubing to impart some of the latent heat of the water vapor to the feed water. i
Water temperatures below oo~6!0 (37,7~J4IJ, 3°C) and water pressures up to 1200 psi (311,!3 MPa) are not unusual. Furthermore, the latest design is 72oo
Water pressure reaching ps+t (μ26.μ MPa) and 7
A water temperature of 00"F (J7/, /"C) is considered.

Currently, steel (carbon steel and stainless steel) and sometimes nickel-steel alloy (Monel nickel-steel alloy) are used in feedwater heaters (*Trademark of Inco Corporation).

Even though feed water is treated to remove chemicals and other impurities from the feed water, cheeping corrosion can still occur.

-Free oxygen corrodes steel. Super Alloy is Shige Shige.

Due to its high work hardening rate, it is difficult to form into tubular shapes. High copper content materials are generally undesirable because copper and corrosion products are believed to be deposited on the boiler pins and transferred into the steam. These undesirable entrained products enter the turbine resulting in low efficiency. In fact, operators desire to eliminate as much copper pickup in the water vapor as possible. This is because copper from the steam is plated onto the turbine blades, contaminating them and reducing their efficiency. It is also believed that copper deposits may form local batteries with iron alloys and accelerate corrosion. Although nickel-copper alloys have chemical and physical properties that are otherwise superior to other alloys, operators tend to avoid these types of alloys. However, the use of low carbon steels or stainless steels in place of currently available nickel-steel alloys is not always satisfactory because these materials do not have the required corrosion resistance, stress corrosion cracking resistance, or strength. As a result, maintenance costs increase. Furthermore, in the case of carbon steel, 3
Undesirably short lifespans of between 1 and 2 years have been reported. Such conditions are in contrast to the desired operating time of: 20 years or more. Thus, power plant operators are perplexed when faced with steel corrosion, expensive alloys, and nickel-steel alloys containing large amounts of copper.

There is a clear need for a suitable alloy with corrosion resistance, strength, and processability suitable for feed water heaters, chemical and petrochemical plants, and other similar applications.

[Essentials of the invention]

Therefore, according to the present invention, an austenitic steel having a low working hardness rate suitable for industrial vessels, particularly heat exchanger tubing for high temperature and high pressure applications, is provided.

However, the usage is not limited to this. The alloys of the present invention combine improved corrosion resistance with the required high strength in lower cost systems than more expensive alloys. This alloy exhibits excellent stress corrosion cracking resistance and excellent high temperature corrosion resistance.

The steel of the present invention is susceptible to tube forming and other cold working treatments because of its low work hardening rate (due in part to its nickel-chromium bond). Furthermore, by varying the titanium content, single-age hardening and non-age hardening characteristics can be developed. Approximately 0. Titanium levels below r4 produce a non-aging effect, while titanium above 0.14 increases age hardenability.

This alloy contains about 3 to 3 ounces of nickel, about 1 to 1 ounces of chromium, and about 3. Molybdenum up to j4 and about ko~!
,! Copper of regret, titanium of up to J4, manganese of approximately 0.2, aluminum of up to approximately 0.1
Contains up to 4% cerium, up to about O0λ nitrogen, balance iron, and small amounts of other impurities and processing aids (calcium, boron, silicon, etc.).

[Preferred embodiment of the present invention]

The addition of a measured amount of titanium gives an age hardening response of at least &<7 Kml (#/J, 7 MPa) yield strength and a tensile strength of 17 Ksi (rλ7.≠MPa) in cold working/annealing conditions. Titanium increases the work hardening rate of the alloy. Copper, chromium and molybdenum improve the corrosion resistance of the alloy. Aluminum, cerium, boron and calcium help deoxidize the alloy. Nitrogen can be added as an austenite former to low-timene level alloys. Nitrogen also helps aid the corrosion resistance of the alloy.

Nitrogen increases the strength and also increases the work hardening rate of the alloy in the annealed state. Table 16 below also shows a number of heats within the above composition range. The heat saw is a low titanium non-age hardening alloy embodiment.

Example 1 Heat l- was evaluated for stress corrosion cracking ("BCC") and hot water corrosion resistance in one set of tests. This heat is applied to the cold-rolled state (
Monel alloys goo and S tested and annealed in heat-treated condition at OR) and taoo'P (tooo C)
Compared with OU stainless steel.

The results of the stress corrosion cracking test are shown in Table 2 below.

The SCC test uses a U-shaped curved sample to
ν(3ts-zz”c). Global corrosion tests were performed in deaerated water by hanging the coupons from insulated hooks. Weight change in underwater tests was !00 hours later. and ioo.

After a period of time, it was determined by weighing the unwashed sample. Average corrosion rates were performed on cleaned samples after 1000 hours.

All test materials were 00725 inch gauge (O,
It was in the form of a strip with a width of 2.3 inches (2,3!α). Experimental compositions were tested at CR304 and/or CR+17 for −0 10.z hours, water quenched + 1 aoo”P (760° C.) / / hour air cooled. Commercially available Monel alloy μ
00 (nominal composition: 32.jt64 copper, cast iron, 1.
04A4 manganese, 0.14 silicon, o, its carbon,
The remainder is essentially 1c nickel) and 5O4L stainless steel (nominal composition: /r, 094 chromium, 9./14 nickel,
/, 774 manganese, q734 silicon, 0. Comi 4 molybdenum, the remainder being essentially iron) was compared with Heat 1-.

Only one alloy, sou, cracked in the tooy/4 NaCI solution during the 720 hour test.

No SCC cranking was observed in heat l- ◎ During boiling 1134Mgc12: t'J ite t'! , hee
t/m 3044 stainless steel also showed high SCC cracking expansion resistance.

In boiling A304 NaOH, the heat saw caused mild cracking and also mild surface corrosion. Alloy 3014 underwent gross cracking and corrosion, while Monel alloy goo was corrosion resistant in this environment.

In summary, Heat Saw appears to exhibit superior 8CC resistance and better resistance to caustic and chloride SCC than 1 Alloy 300.

A high nickel content improves this SCC resistance.

1 in the high temperature i deaired water test shown in Table 3 below.
The overall corrosion rate of Alloy 1 was the same as that of 300 stainless steel, but slightly higher than that of Monel Alloy 200.

Table 3 Heat l- remains OR, others are OR Mu12 -0.0koJ -0-0310,10-o,ot
o - o, ioz o, i.

Monel alloy 4400 -0.10co -o, oau o, co3#
-1,! 7ta -44koj O,73 stainless steel 30- -0.017 -0,0koj 0004# +
0. OJj -0,0110,D6* Rate measured on cleaned sample.

Examples Cojitos 1-3 and 1-ko (1-ko4 melts) were vacuum melted and cast into ingots with a diameter of 1 inch (lθ, ltα). Forged % inch (413α) square and forged % x co x l coin inch (/, riixz, or x 30,
It was made with a flat plate from Japan (Vt country) under frequent heating at 2001 (1177°C). After processing the flat to a uniform thickness, this is co/! Hot rolled to inch (0,6aα) at 0″F. Hot rolled inch strip to 1yz
ov (706 °C) for 71 hours with water cooling and pickling prior to cold rolling. In order to measure the work hardening response, hardness tests and tensile strength tests were conducted at each level of cold working. For the production of relatively small diameter, thin wall threading, low work hardness rates are highly desirable.

Yield strength is particularly important during high level cold drawing υ such as Aθ~04. Many steel tube mills produce large diameter hot-worked steel tube shells, which must be reduced in size during multiple stages of cold rolling and annealing. Experiments have shown that alloys with low yield strength after high cold drawing can be cold-worked more strongly without exhibiting cracks, requiring fewer annealing steps and lower manufacturing costs. .

The accompanying figures show that H)/A also has a lower yield strength after high reduction rates than the low nickel content HEAT1 and /J.

In addition, after cold drawing 60~RO4, the yield strength of heat LT is lower than that of the commercially available alloy Incoloy Alloy 100 (*
Incoloy alloy r00 is shown in this figure for comparison purposes only. This alloy is a general purpose alloy.

It has excellent processing properties and is easy to process. The present invention has been developed taking these points into consideration.

All heats have excellent malleability. Tensile strength data for cold rolled strips with increased titanium content are shown in Tables g, j, 4.

Titanium content! , θ%, the work hardening rate increased, but no change occurred when titanium was increased to 2.34. The aged tensile strength test results shown in Table 2 show that with a titanium content of approximately /714 and a low level of cold working, a yield strength of 40 Kml and a tensile strength of 120 Kii can be obtained. In fact, a combination of a slightly lower titanium content and a cold rolling of about 90% would be optimal for the feedwater heater.

Table 7 below shows the strength and ductility properties at the annealing/aging stage.

Example 3 A corrosion test was conducted on heat dazzlers. Corrosion test environments for water supply facilities and other possible applications were examined.

Table r shows the SCC test results in sodium chloride and sodium hydroxide solutions.

The alloy of the present invention has been shown to be more resistant to 4 sec (corrosion caused by chloride E sodium hydroxide) than 301 stainless steel. The relatively high nickel content of the alloys of this invention results in chloride and caustic cracking resistance.

These test results also demonstrate the excellent resistance of this alloy to polythionic acid cracking. This crackling is a common cause of breakage of stainless steel and high nickel alloys in the petrochemical industry. The effect of high titanium content on carbide deposits is believed to be responsible for the excellent polythionic acid 8CC resistance.

Table 2 shows the results of the global corrosion test.

Tables j and 2 also show that the alloys of the present invention have resistance to environments other than feed water heaters. Molybdenum addition of λ~34 significantly improves the resistance to hydrochloric acid. Copper additions of pg or more improved sulfuric acid resistance. The combination of steel and molybdenum appears to improve resistance to phosphoric acid. The alloy of the invention itself is also suitable for chemical and petrochemical applications.

The strength of alloys designed for pipework applications is usually based on the tensile strength of the alloy that constructs the equipment.

In the cold-rolled and stress-relieved condition, the alloy system of the present invention typically has a 120
This corresponds to the minimum tensile strength of Ksi. This value is Inconel alloy 62! It is highly comparable to alloys such as ROI and Incoloy alloys.

Table 10 compares the minimum tube wall thickness of Monel alloy 4Aoo, sop stainless steel and the alloy of the present invention for various temperature and pressure conditions. Table io shows a comparison of the minimum wall thicknesses of the listed alloy tubes. The next heavier standard wall thickness was used to calculate the 1-ft whiteboard weight.

To make objects, especially seamless or welded pipes,
A stress relief heat treatment of about /100° to #00″p (zy, 3 to 740°C) for an appropriate time can be performed on the object or tube made by a method known to those skilled in the art. Yes, this time is of course a function of the chosen temperature and cross-section size.

More specifically, the non-age hardening tube is drawn to its final size and held at approximately 17,000 to 2,000"F (767 to
Annealed at 233°C), straightened, and shaped into an appropriate shape (desired shape)
Bend it to about ttoo, t4coo''P for about 3 hours,
Stress can be removed. Age hardening tube.

Drawing to final size, appropriate hourly wage / 700-λ00
Annealed at 0ν, linearized, 1100-14I for about 1 hour
Aging treatment under 000, bending into appropriate shape, approximately 1100~/
Stress can be relieved for an appropriate amount of time at 1700″F (
This simultaneously age hardens the tube).

Due to the relatively low chromium content, the pitting corrosion resistance of the alloy of the present invention is approximately equal to that of stainless steel SOU, and it is not recommended for applications where high local corrosion resistance is required. Low chromium content also reduces intergranular corrosion resistance and limits applications in highly oxidizing environments such as nitric acid.

The preferred composition for the overall strength, corrosion resistance and economy of the feedwater heater is Heatt (#N1-/A Cr-1c
ui, rr+-koMo=remainder F.). This composition appears to have the necessary mechanical and corrosion properties for a high pressure material. The composition also has excellent overall corrosion resistance in hydrochloric, sulfuric and phosphoric acids. This composition also has excellent resistance to polythionic acid corrosion.
It shows the possibility of use in petrochemical aspects.

The present invention is not limited to the above description, but can be modified and implemented as desired within the scope of the spirit thereof.

[Brief explanation of drawings]

The attached figure is a graph plotting yield stress and reduction ratio. Applicant's agent Kiyoshi Inomata - Npei Mata%

Claims (1)

[Scope of Claims] t about 1 to about 3 nickels, and about 7 to 1/2 nickels;
9fk glue 4m, about 1qb to J, Jl of molybdenum, about flathead to! , j'14 of copper, titanium up to about λ, j-, and about 1. ! - up to manganese and about /, J'
Silicon up to A, niobium and tantalum up to about 1/2, and aluminum up to about O, flathead 1. Approximately 0. Serium futo up to l-, boron up to about (101-) and about O,
An austenitic, high-strength, corrosion-resistant nickel-iron-ripm alloy consisting essentially of up to J nitrogen, the remainder primarily iron, and trace impurities. Ko, about 3 nickels and about 169! Nori pm and approx.
2 m of molybdenum, about 4 g of copper, about 4 g of titanium, up to about 0.7 m of cerium, the balance essentially iron, and traces of impurities. Alloy according to item 1. 3. An alloy according to claim 1 which contains about 0,114 or more titanium and is age hardenable. Hiro About 28 Mokkel, about 764 Chrome, and about 2
The amount of molybdenum, the amount of copper, and the amount of approximately 0. Up to f titanium, approx./up to manganese, approx. 0. μ-ringing silicon,
Approximately o, a4. up to niobium and menthol, about 0.000, nitrogen up to about 0.000. 2. An alloy according to claim 1, comprising up to 1/4 of cerium, the balance being mainly iron and traces of impurities. An alloy according to claim 1 that is non-age hardenable and contains less than about 01r4 titanium. 2. The alloy according to claim 1, wherein the alloy according to claim 1 is heat treated for up to about 16 hours at a temperature range from about 1 lOOc' to about 4 coo. 2. An alloy according to claim 7 in the form of a tube. The l tube has a temperature range of about 1 ioo' to lμ00ν.
An alloy according to claim 7 which is heat treated for up to 6 hours. Essentially about J4 to 32% nickel and about 12%
Chromium of about 14 to 3. ! The molybdenum of the sound and the approx. J, J-The approx. of the copper and the approx.! up to about 1% titanium, up to about /,j% manganese, up to about /,J4 silicon, up to about 14% niobium and mental,
With aluminum up to approx. Approximately 0. Industrial products made from high strength and corrosion resistant austenitic alloys consisting of up to 1/4 cerium, up to about 14 boron, up to about 0.2 nitrogen, with the balance mainly iron and traces of impurities. container. 10. Nickel alloyed essentially about 2114 and about /A
The regrettable chromium, about 24 molybdenum, about 14 copper,
3. An industrial container according to claim 2, comprising titanium of about 0.14% Ir4, cerium up to about 0.14%, the balance being mainly iron and traces of impurities. ii, the alloy consists essentially of about 284 nickel, about 100% chromium, about 200% molybdenum, and about 4! Excellent copper and
titanium to about o,res, manganese to about 74, silicon to about oB, and about 0. niobium and mental to about 0.05 μm, nitrogen to about 0.000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 An industrial container according to claim 2, which comprises a thick layer of water and a trace amount of impurities. 12. An industrial container according to claim 2, wherein the alloy contains about 0.114 or more titanium and is age hardenable. 3. An industrial container according to claim 2, wherein the IJ alloy contains less than about 0.114 titanium and is non-age hardening. 7g An industrial container according to claim 1, which is a heat exchanger. 1. An industrial container according to claim 1, which is a feed water heater. lt. An industrial container according to claim 1, wherein said alloy forms piping inside the container. /7 An industrial container according to claim 1 used in the chemical industry and petrochemical industry. lt alloy is cold drawn from its original size by approximately 201 cm,
An industrial container according to claim 2, which is formed into a tubular shape. 9. An industrial container according to claim 9, wherein the alloy is heat treated at a temperature range of about //DO" to about taoo"P for up to about 74 hours. 〃, the tube made from the above alloy has a diameter of about 1000″ to lμ
An industrial container according to claim 1 which is heat treated for up to about 74 hours at a temperature range of 0.00''F.
J Naruno to lt14 chromium, molybdenum up to about 3, and about! Copper to the bitterest and about ko,! titanium to the extreme, manganese to the extent of about 1, its silicon up to lt4, aluminum up to about 0.2, boron up to about QO1, nitrogen up to about 0.24, cerium up to about o,i, and the balance mainly iron; An austenitic, nickel-iron-chromium alloy that contains trace impurities and exhibits high strength and corrosion resistance while minimizing copper loss into the fluid stream. 2. nickel of about 1 to 32 ton, chromium of about 1 to 94, and about 1 eIb to 3. ! Of molybdenum and about 2 to rB of copper, about ko,! Titanium up to 14, about /, manganese up to 14, about /,! up to 4 silicon, up to about 74 niobium and tantalum, and about 0
．． containing up to 24% aluminum, up to about 0.24 tcs cerium, up to about 0.014 tcs boron, up to about 0.24 tcs nitrogen, the balance being predominantly iron, and trace amounts of impurities; A method of producing an austenitic alloy exhibiting high strength and corrosion resistance, the method comprising the step of heat treating the alloy at a temperature range of about 1 IOO" to 14 AOO"F for a suitable period of time. 3. Approximately: nickel of MA4 to 3 K, chromium of about /K to /91, about 14 to J, 1% molybdenum, about K to J,! 4 copper and approx. titanium up to j4, manganese up to about 1,14, silicon at about t, z4t, niobium and mental up to about 14, about 0
．． Tubes containing up to 24% aluminum, up to about 0.24% cerium, up to about 0.014% boron, up to about 0.24% nitrogen, the remainder being predominantly iron, and traces of impurities. In the manufacturing method. a) forming a tube; b) sizing to a predetermined size; C) annealing the tube; d) straightening the tube; and •) heat treating the tube at a temperature of about 1100° to 14 AOOv for a suitable period of time. A method according to claim 23, wherein the music pipe is age hardened. Δ Claim 93: Curving the pipe into a predetermined shape
Method by term. A method according to claim 3, characterized in that the tube is bent after bending. I. A method according to claim 29, wherein the annealing step is carried out at a temperature of about 1700" to 2000" for a suitable period of time.