JPS5913591A - Non-sensitizing welding procedure - Google Patents

Abstract

PURPOSE:To prevent the generation of intercrystalline corrosion and intercrystalline type stress corrosion cracking in welding base metal in the stage of welding austenitic stainless steel members, by subjecting a welding groove to a buttering treatment then to an overaging treatment and welding the members. CONSTITUTION:Austenitic stainless steels having sensitivity to intercrystalline corrosion and intercrystalline type stress corrosion cracking are overlaid with beads by a buttering treatment in the positions corresponding to the weld heat affected zone in the weld zone and are then subjected to an overaging treatment for 216hr at 745 deg.C in the stage of butt welding said steels to each other. The buttered groove part is subjected to forming to permit welding easy, whereafter the groove is welded by main welding. The weld heat affected zone having high sensitivity to intercrystalline corrosion and intercrystalline type stress corrosion cracking is subjected to a bead coating treatment by buttering and an overaging treatment after welding to decrease the sensitization of the above-mentioned sensitivity that the base metal in the weld zone possess, and the generation of intercrystalline corrosion and cracking is thus prevented.

Description

[Detailed description of the invention] (1. G.S.C.C = Inter granu
lar Stress Corrosion Crack
ing) improve sensitivity. A-Stegite type sub/
Concerning two methods of de-sensitizing welding of steel.

When Kichi Sulfite stainless steel is heated in a temperature range of 500 to 850° C. for a certain period of time, chromium carbide precipitates at the crystal boundaries. Then, a chromium-depleted layer is formed near the grain boundaries, resulting in a so-called sensitized structure, resulting in a grain boundary corrosion depth of 1. G. S. C
．． The C sensitivity 141 has become high, causing various problems.

In addition, examples of austenitic stainless steel include SOS304 and SUS specified by JISK.
a i a and d, the main ones are SUS2F11
, 202l, 301. 3 (+ 2, 303.
305, 317, 321, 347l, 384,
Same XM7. The monthly charge '1+i properties of the same Denless steel have been revised to reduce intergranular corrosion and 1. G. S. C. Those who make C 1υ no city
As a solution, the following methods have generally been used.

■ SUS304L and SUS: 3 1 6 1
, steel type 4 with low carbon content, such as snow, is used.

■ Use steel types such as SUS32 and SUS347 to which 13 carbide stabilizing elements are added. '(3) Perform aging treatment.

1 to 1, among the conventional methods of prevention.

■ is due to the slow precipitation of chromium carbide (d, WLd) when the carbon content is below the solid solubility limit of the matrix, and this is due to the slow precipitation of chromium carbides (d, WLd), which is difficult to achieve when heated for a short time such as during welding heat recycling. It has an effective chewing effect, but it is recommended to use it in the sensitization temperature range.

After a long period of time, carbides begin to precipitate. Also, there are problems such as low high temperature strength compared to 5US304, 5US316, etc.

■In the temperature range of -500 to 850℃, intergranular corrosion can be prevented by adding TI or oil, which has a stronger affinity with C than that of cr and C, to form 1゛l or rare carbides and stabilizing Cr. The high temperature strength is also relatively high due to the method of preventing
It is widely used as a corrosion-resistant material in high-temperature corrosive atmospheres. However, if this material is used for a long time at a temperature of 600 to 800 degrees Celsius, embrittlement and red heat cracking may occur, and the integration cost is significantly lower than that of SUS3 Tl 4. -" If you remove two, there will be m points.

(3) Id Tomoto-1 is sensitized, crystallinity region c- is subjected to fixed-time aging treatment rll+, and Fig. As a result, Cr in the Cr-deficient layer is formed and transitions to a Cr-deficient layer.
Including 1: This method utilizes the phenomenon (state at time t) in which d recovers by more than 12% of surface 1 area 1't.

SUS 3 o 41J's! Jll fever'%f'+
An example showing the relationship between (temperature and Q/time) and the sensitization region is shown in FIG. In this figure, the d-sensitized region is diagonal (/(P
When heated for a long time at a constant temperature of 71 degrees, the ridges become sensitized.This indicates that the ridges shift to the -II sensitized region (I), which is the recovery of the Cr-deficient layer of kt l j]lΣ. I believe that this phenomenon is due to the 5US3o4°S U
By using θt If of S 31 a and performing heat treatment, 1 grain boundary disease food and 1. How to prevent G, S, C, C, wood aging treatment r"l', j5 l)-<
f), it is noticed. However, there is a major problem with the adoption of wood aging treatment method 1. That is, if this method is to be applied to a welded structure, it is of course necessary to carry out the process after full welding. One welding groove person
／、After that, I have to deal with V. Because, ``IrM statute of limitations Fi+! After welding, welding is performed on the mother A4 side of the welding bond (61-welding hot shadow J!!
71. The effect of over-aging treatment is high because the solid solution is more than 1■■. It might be seven minutes. Therefore, weld ri+7. If you want to perform this process after assembling the i-monomono, you can use small-sized ones with a simple shape (Tn), but if you have a large structure, you can use the structure 1 This method cannot be used if there is a heating furnace with a capacity suitable for green vegetables.
Even if there is a heating furnace, the temperature of the crushed material cannot be increased even if there is a heating furnace. 7JL, SUS ao 44), S [JS:
+x6 (You can just use a hole punch such as A, and it is fine.) Grain corrosion that does not cause problems even when the green objects are large, and 1,
Providing a welding method that prevents G, S, C, and C.
For this purpose, the present invention includes each of the following steps.--The MiL method for non-sensitizing welding of stenitic stainless steel members is the object of the invention.

(a) HAZ (Welding Heat Affected Zone: hereafter abbreviated as F'HAZ) of the wetted part during main welding. The process of making an e-judge <b
), (a) Upper processed part (g' vc and jf:!
Perform aging treatment (Ilj) Part 1 of I-Sefu (C) (Beveling of A, L culm (d), North welding (related, I do (])) and Part 1 of (c) process l'l
Main welding is carried out by χ J t on the completed part.In general, the above gist of the invention includes forming 411\7, 1-, as follows. ] 1 is common.

fi+ 1:, 1-('AZ schedule (11'') during welding
, and the stage where the beats are played.

+21 fl, 1-1-culm treated section, lJ K undergoes overaging treatment -L culm.

(3)) τIL month groove addition - process of performing -.

(4) Process of forming and assembling.

(5) Regarding the main welding part, fl, 1. , +2), +
Approximately 1 liter of main welding is performed on the members that have undergone the upper steps of 31 and (4).

In addition, the size, shape, size, and tone of objects: (1) - → (3) - → (2) → (4) - → (51, +
31-→(1)→(2)-→f41-) +51 'l
ij: if) -+ +21 →t41 →f3)
-+ +5) , 1 (DL81/C1,-)-c
Also good. The point is (2) Ail K fl of overaging treatment,
The main welding process (5) is performed after (2).

It's a good idea to use a welding rod used for target welding for the beat welding involved here.

Here, ``forming and assembly J D J-'', the reason why the culm was deliberately not included in the purpose of the invention is because it is similar to welding plates.
C molding/use l, and 111 bell + Pi' are required t(7
This is because there may be cases where there is none.

1. The groove cutting in the present invention includes only υ111-, which adjusts the joint surface so as to form a joint ('(drop)').

Therefore, as seen in the recent narrow gap welding θ, the opening angle of the groove is small.

Even if this angle is 0 and the addition is such that the joint surface and its vicinity are rubbed fiJI, it still corresponds to the groove addition 1-VC in the present invention.

FIG. 2(a) and (1)) show the solution 1 and group 1 of the present invention. Illustrating a general example of the law no. In both figures, heat 3 was applied to trJ-1 in advance, and then vC-1-
, doing welding. 3 is ``E welding 1 prefecture welding 1 de C
be.

The present invention is full of childhood! Due to the effect of welding bead 1., the embossment of grain size, corrosion and 1. It uses the effects of low G, S, and CC sensitivity, but these effects +4! : Shown in all FIGS. 3 to 9 and Table 1 -4° FIG. It's a bud, in figures 4 to 9,
Examples of research results in the area of sensitization that are currently being investigated are presented.

Figure 4 shows the difference in ring 1 quality and the difference in C% on the sensitization area of SUS 304 steel, and Figure 5 shows the effect of iC% on the sensitization area of macebunite stainless steel.
Figure 6 ifj is SUS 3o4L steel (Ichikawa ratio: 0022%c, +9..31%Cr).

939φNi) and 5US316L steel (n with claw closing,
o 23%C, ] R, 42%cr, 12.62
%Ni.

Figure 7 shows the sensitization region of S [J S 347 steel (
Weight: n: , 0 in LIZ. (17%C, 18,41%
Cr, t 1.75%Ni, fl 81%Nh
) m, II 65 Section 11 immersed in NO3 / 6 / Kotoki no Sharp #, [L area, Do, Fig. 8 i, is [Is
, 316 steel (heavy rn-ratio o, 07% C, t7
．． 9% Cr.

11.1 Chi Ni, 22nd MO) Kasuri 1 politicization area is 4
- The influence of the normalizing grade is shown from -1+1 and (2-C known techniques) in the 114 aging region, respectively. In addition, Fig. 9 1・C, I, 5 US316LWI was solution treated at 1090℃. This is a diagram showing the differences in the precipitation areas of M2.C in the case of M2. and (υi 'j''+: Ninojigu Ichiriki (,
・(''.

1. In each figure 15, J1φ11.5 effect rJ11 is performed, and the once sensitized part 4) is
I can see how he is getting into his territory.

Table 1 shows the utilization of the intergranular corrosion test (JIS GO575) conducted on SUS 304 steel by boiling sulfuric acid and copper sulfate C in the middle of the night for 16 hours.

IjJ fraud and fiAZ fd without overage processing:
Perfect grain 11"11- by 650℃ x 2hr sensitization treatment
In contrast to Kosei J, which has undergone a proper aging process, IrJ, 4A and HAZu are less prone to cracking.

- On the other hand, the weld metal (heat) should be over-aged.
No cracking occurred at all in the samples without F2 and in the samples subjected to any type of f+ aging treatment.

Although the cause of this is not surprising, it is thought to be due to the formation of δ ferrite or dendrite between the 4-rows in the genus.
A correlation between the intergranular corrosion test d in sulfuric acid and copper sulfate solution adopted here and stress corrosion cracking LL due to polyethylene acid is also recognized, and it is generally considered to be a more severe test than the stress corrosion cracking test using polyethylene acid. However, because it is easy to implement and has high detection sensitivity, it is often used for experimental determination of sensitization resistance.

The present invention will be explained in detail below with reference to Examples. Example d
,500~700℃ sensitized AA degree range.The high temperature heat exchanger of the benzene plant used is subjected to 1Vi1 intergranular corrosion treatment and resistance to 1. The method of the present invention was applied as G, S, C, and C processing.

That is, using the plate or forging of 5US304.

The position corresponding to the heat affected zone of the main weld line is determined in advance according to JIS Z32.
Stainless steel coated arc welding rod shown in 21 1) 3
o A bead was formed at B, and after aging treatment at 745°C for 216 hours, one assembly was performed and main welding was performed.
Manufactured a heat exchanger.

Since the internal fluid of this heat exchanger contains -C myelinated hydrogen, there is a possibility that boritinic acid will be generated when the operation is stopped, but after 2 years and 1 year of operation: +gi +, Y1ii
Trouble i-1, occurrence) 7 has not occurred. 1. The lj method of the present invention causes surface 1 intergranular corrosion and 1 lil 1. G, S, C
, C processing and 17.

It can be seen that it works extremely effectively.As shown in the series, I (A
The surface of the Z planned area is sharpened in advance to a depth of 71. By covering the bead with a hard bead and overaging it, the whole body is made less likely to be sensitized. Even if main infiltration is performed on this member, since there is a beat on the surface of I-I AZ, )(, AZ is up to 1, which is difficult to sensitize.

Therefore, the structure as a whole is extremely
? -Corrosiveness and surface 11. High in G, S, C, and C properties.

Furthermore, in the present invention, a large-sized guest reception (141
t'V'7. Interfacial corrosion, resistance 1. G, s, c, c: Due to over-aging treatment, the structure after all welding J7 is not \ but 9 sets \
7. Since the process can be carried out at the Ail bare stage or semi-finished product stage, a heat treatment furnace capable of heat treating the entire structure is not necessarily required, and the production lead time can be shortened, which occurs when a large heat treatment furnace is used. be.

1- From the effects described above, the present invention υ'-Ilil'l'l interfacial corrosion and abrasion, G, S, C, CI'# required]- Stenitic stainless steel welded structures are optimally used. .

Ming He Zhan's bow bow; (no changes in content)

[Brief explanation of the drawing]

Figure 1: Cr-deficient layer near the grain boundary or 141'
(A schematic diagram of how J-recovered by Sumi-J treatment is shown in Figure 2 (aL (+)). , cross-sectional drawing of the contact part A (Fig.
:304 w1]; I'rif-onoic acid and sulfuric acid/copper sulfate Y dipping (・de, 1, Rue imitation 1 person's mastery/Dozugunf,
Figure 5 iJ: :11-J-graph showing the influence of C concentration on the sensitization region of sudenite-based steel/less steel, No. 6
The figure shows θ11 rise of 65% HNO, θ/f (Gushino in the sensitized region of SUS 304 L steel and 5US316 steel, which is raised from K, Fig. 7 6', J turn boiling 11 mound 65%)
A graph of the sensitized region of SO8:z7 steel produced by INO immersion, Fig. 8. The sensitized region of 1tsUs3t6 is affected by the 4-solution if (: L degree). Solution treatment 17 S [J S 3
This is a club showing the influence between heating temperature 1 degree and heating temperature 11.11 degrees without affecting the precipitation location of M21C6 in t6L steel. ■ Over-aged base metal, 2 main welding beats 3 II A Z part (pre-welded bid) Fig. 4 Fig. 6 Fig. B Fig. 5 @ Fig. 7 Procedure correction - 1 ((1' style) Showa 5 F ■ September IS ゛ Mouth Director General of the Patent Office 11 Display Showa 5741 Patent Application No. 123-00
Name of the bow invention De-sensitized welding
'l inside, j-l'l', + Wj I Wj name ze (
・(620) Mitsuki IT+] Monthly fee for the business interest ceremony, person 1, place, east area, 11 ward, J Shinouchi-11
] 5th No. 1 Kyucho, continuation Sode II (1': (Ka1 () Showa i'u 5 Fui I'+i month 7211 Ereme 1 Chochoui Lordship I'i's f!; 1, Showa 5 Fui l” 'L'r Il' - Request 1st
2330 Relationship with [1sihli if Cruba+1iiiI] "l'b;
1 middle school/11 capital] 1llll<, Il/') inside 111th number jI: and a ladle (r2111 Rin Elementary School 1"!
'+i, ,5. Meeting? 1st generation 1111 people's lock

Claims (1)

[Scope of Claims] A non-sharp welding method for sprite stainless steel members comprising the following steps: (a) 11 A Z of the wetted part during main welding.
Culm. (+)) , (a) L processed part AA K ZJ
t. The process of performing overaging treatment. (C) Step 1- where the beveling of part A4 is performed. (d), There is a spacer in the main weld (1) and (C) soil J
The process of performing main welding on the treated part by χj.