JPS5976694A - Welding wire for high purity ferritic stainless steel - Google Patents

Abstract

PURPOSE:To improve toughness without spoiling the corrosion resistance of the deposited metal of a titled wire obtd. by incorporating extremely small amt. of C and N and adding an adequate amt. of Nb, V and Al, in welding ferritic stainless steel. CONSTITUTION:This welding wire for high purity ferritic stainless steel has the under-mentioned compsn. by weight %: Said wire contains <=0.02% C, <=0.02% N, <=0.5% Si, <=0.5% Mn, 18-25% Cr, 0.5-2.0% Mo, 0.2-0.6% Nb, 0.1-0.3% Al, 0.1-0.5% V, and 0.005-0.12% REM according to need, satisfies the inequality and consists of the balance substantially Fe.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a wire that is used for welding high-purity ferritic stainless steel and has excellent weldability, particularly the toughness vc of the weld metal.

As is well known, high purity ferritic stainless steel mlllld
, Due to recent advances in VOD method or AOD method blue sheath refining technology, C processing N has been significantly reduced, and this high-purity ferrite stealth <4YI u
Since it exhibits poor properties in terms of corrosion resistance and toughness, such as i+n・1 stress corrosion cracking resistance and severe pitting corrosion, its applications are diversifying. Due to its excellent properties, it has recently been used for thick-walled applications such as hot water storage tanks and water receiving tanks.

By the way, welding is inevitable in the manufacture of hot water storage tanks and water receiving tanks, but because the plates are thick, welding π welding wire? It is common to use

However, even with the steel π of this system in which C and N'i are significantly reduced, there is a problem in that the low-temperature toughness of the special π welded metal part deteriorates when the wire sound of the same metal thread is used. Therefore, in many cases, an austenitic wire such as Y316L, which has excellent toughness lK of the fermented metal assembly, is used as the welding wire. However, if one austenitic wire is used, the welded metal part has superior toughness compared to the welded metal part using a matching wire, but the incorporation of N1 into the welded metal part is ≠ 1.
・J There was a problem in that the stress corrosion cracking resistance was deteriorated, which more than offset the characteristics of the steel of this series.

The object of the invention is to solve all of the following problems and to provide a welding luster for high-purity stainless steel that satisfies the corrosion resistance and toughness of the weld metal.

1. As a result of various studies carried out by the present inventors for the purpose 1. 2. When welding high-purity ferritic stainless steel, C and Ni should be extremely low, and the relationship of 50≦'-''≦90 should be satisfied. Add appropriate amounts of Nb and V, and add appropriate amounts of A.
It has been found that if L7J ferritic stainless steel wire is used with the addition of L7J at the same time, it is possible to obtain a dynamic weld metal without impairing the corrosion resistance.

That is, in the first embodiment of the present invention, O: 0.02% or less, N: 0.02% or less, Si: 0.5 q
b or less, Mn; 0.5% or less, Or; 18-25
%, Mo; 0.5-2.0 ratio, Nl); 0.2
~0.6%, Al-; 0.1~o, s%, V; 0.1
~0.5 qI) and 50≦111≦90J? This is a welding wire for high-purity flite-based stainless steel that satisfies the requirements for weldability vc5, with the remainder consisting of Fe and unavoidable impurities. ) was added at 0.005 to 0.2% in the α range.

The reasons for limiting each alloy component of the welding wire of the present invention will be explained below.

C and T1 are interstitial impurity elements for high-purity ferritic stainless steel, and when they combine with Cr to form ferrites and nitrides, reducing the toughness and ductility of the weld metal, they can cause the formation of carbon grain boundaries. It is desirable that it be as low as possible, as it predisposes it to corrosion. However, in the wire of the present invention, l
Since intergranular corrosion can be eliminated by adding tNb and V, -F: 0.02 to 1 is acceptable.

81 is typically low in terms of the toughness and mechanical properties of the weld zone. (It is an essential element in the manufacturing process of the wire of the present invention, and its presence is inevitable to some extent, but its maximum
``In each state, 5 degrees are too sweet, and if the amount exceeds 0.5, the toughness and ductility of the incorrectly attached goldfish tend to decrease, so S
i was set to 0.5% or less.

Although its low Mn content is important for improving the corrosion resistance of the deposited metal, it is an essential element in the manufacturing process of the wire of the present invention, just like Sl, and its presence to some extent is unavoidable. But Ll,
If the amount exceeds 5%, the corrosion resistance of the weld will deteriorate;
．． The upper limit is 5 tickets.

Crt (a basic element for L-ferritic stainless steel, and an essential element for obtaining high corrosion resistance. However, as the content increases, it not only causes the toughness of the weld metal but also reduces the manufacturability of the wire of the present invention. 18-25 as it also harms
It was hot.

Mo1qr is extremely effective in improving pitting corrosion resistance in the presence of chlorine ions, and corrosion resistance is significantly improved as the amount added increases. However, if it exceeds 2 points, the ductile-brittle transition temperature increases, so the range was set to 0.5% to 2.0%.

Nb combines with C and N, which are harmful to toughness, ductility, and corrosion resistance, to form carbonitrides, and suppresses the precipitation of Or carbonitrides. In order to obtain such an effect, it is necessary to have a content of 15 times or more of 0 + N, but if the amount exceeds 0.6, it will cause hot cracking of the weld metal during welding.
bH skin range was 2 to 0.6.

Like V and Nb, it is a strong carbonitride-forming element and has the same effects as Nb. Then, in the range π of Nb between O02 and 0.6, 50≦-Nb-IA! Ic so that −≦90
When V and Nb'lf- coexist, intergranular corrosion resistance and toughness become a problem. However, if it is less than 0.1%, it will not be effective, and if it exceeds 5%, the toughness will deteriorate and the cost will increase, so the value was set at 0.1 to 0.5.

A1's strong J-deoxidizing power completely reduces J-carbon in steel.

This also reduces the surface tension of the molten metal during welding, allowing smooth transfer of the molten metal. It is also effective for fixing N by forming all of the N and improving toughness and ductility. For this purpose, it is necessary to add 0.1% or more to one piece of F rubber, but 0.1% or more is required.
If it exceeds 5, the weld metal will become brittle, so 0.1~
It was limited to 0.6%.

The high temperature cracking susceptibility of elbow IM welded metal is completely improved, but 0.0
If the ratio is lower than 05, no effect of improving r is observed, and if it exceeds 0.2, the toughness and hot workability of the weld metal will be damaged, so the ratio was set to U, 005 to 0.2.

In addition to the above-mentioned alloying elements, the production of the wire of the present invention was carried out for 11 days to contain only traces of impurity elements.

J Kakishita π Lists examples of the use of the wire of the present invention, and its properties 4 - Effects of the wire of the present invention in comparison with comparative examples.

Table 1 shows commercially available high-purity fibers listed as AA to be welded.
Chemical group IJV of light type suanless steel, (A)・Not shown 1
, na = 1' - This wave sound is r 6 + nm to the thickness of the moon
It is. Chemical group J戊4・Wire used in Table 2
Not shown. Go~2 Table π doesn't show the wire picture? 1a11 and N
[l 121dA commercially available austenitic wire, N[Lll is Y6[]9L (1,2++++n96
), No, 12 [Y316L (1,2mm';
6). 111~H [50 to the wire of Llo
kg After vacuum production 1. Forging, wire drawing, annealing, pickling process? After that, it was finished into a 1.2i, lda wire. Welding was performed by TIG butt welding under the welding conditions shown in Table 3. After welding, various test pieces were cut out and the weld metal was subjected to Charpy impact tests, bending tests, intergranular corrosion tests, and stress corrosion cracking tests.

These are the results of an impact test and a bending test of Ka4 exposed welded metal. As is clear from Table 4, the impact value of the welded metal using the VC wire of the present invention is slightly inferior to that of the orstenite wires NIL 11 and N[L12, but compared to the comparative wires of other ferrite threads. ′, it has a strikingly high impact of 1 when tilted. To be more specific, N[L, which has the same composition as the moon to be welded, has the lowest impact value up to 5.6t, and even at 25C, it only shows a value of about 2 ky/ffl, which is amazing. In addition, when comparing Δ1 and V to NIL 5.6, China and Germany [chilled t1α) and Nα8, respectively, the negative value tcr increases slightly when compared to T1α5.6, but it is still low compared to the wire of the present invention. ,
It is about 5 kg/cd at 25C. This shows that a weld metal with poor toughness cannot be obtained by adding Ai and V alone. No, 9 work N110 old), Ai, ■? The impact value of the weld metal of these wires (f) is also different from that of the wire of the present invention. Comparatively low.

71♀ punch-υ'QV (in the case of the present invention wire VC, J,
Nα9.
10 to 3.5≠7 no or less. On the other hand, as shown in Table 4 in the bending test results, no cracks were observed when using either the wire of the present invention or the ratio I bite wire including the austenitic wire. Light system/resugugo smell-(1 love 1 also toughness, ri 1ξ1 i 1 call T・Ij
[For heating the bath-deposited gold circle] Jadeite-based stainless steel wire +: fNb, A-1,4-'- and ■ke suitable silk-type composite addition, σ61 (--"'-"" y7.1-50~
90's 11 ton circle 11/c shift J: IC Toka'IE Karu 3, Table 3 TIG welding conditions (Note 1) Back shield gas t" 1st lot only auxiliary 4th
Table Impact test and bending test results of weld metal 1) Bending test temperature is 25C.

Note 2) 01 No cracking Note 6) Impact test 2 +arnV non-chillable impact test test piece i Jl:S No. 4, 10x6 sub size.

Next, the results of corrosion tests on welded parts will be explained.

Table 5 shows the results of the intergranular corrosion test and stress corrosion damage test of welded parts. As is clear from Table 5, Bic acid-(lf
In the intergranular corrosion test using lj-acid copper solution, the invented wire was
Comparison 1)・r-＼・Even if some cracks were to occur, no cracking occurred and the grain boundary corrosion occurred. However, the stress corrosion cracking test using M141 solution in Section 42;
Among the 11 wires, cracking of the weld metal π using one austenitic wire occurred, but no cracking occurred in the wire of the present invention or in the ferritic wire among the comparative wires.

Note u Intergranular corrosion test ヰJ'l5O (Note 2 according to 1575
) Stress even split IL test in accordance with JIS G 05761c Note: ○; Discount #'L7z (,, ×; Crack occurrence) Comprehensively looking at this from the above examples, high-purity ferritic stainless steel It is clear that by welding, it is possible to obtain a deposited metal with excellent toughness without any loss of stress corrosion cracking resistance or ductility, and the toughness of conventional cometal-based materials is much lower. In addition, concerns about stress corrosion cracking when a wire thread is used for the austenite 1 can be eliminated at the same time. % hot water tank,
If the wire of the present invention is used when welding thick plates of high-purity fluorite-based stainless steel, such as water tanks, etc., it will improve workability during manufacturing and stress corrosion cracking during the process. Being good is clearly a strength.

Since the present invention does not contain Ni'(z), it is advantageous in that it can be manufactured at a lower cost than the conventionally used austenitic wire.

Procedural amendment (voluntary) 1. Indication of the case 1987 Patent Application No. 187046 3. Person making the amendment Relationship to the case Patent applicant address Mr. 3-4-1 Marunouchi, Chiyoda-ku, Tokyo
Name (Name) (458) Nisshin Steel Co., Ltd. Representative Yuzuru Abe 4, Agent 162 Detailed explanation of the invention in the specification column 6, Contents of amendment The detailed description of the invention has been amended as shown in 8L below. do.

(a) Enter 9/C11J as “2” in F2 on page 8, line 16 of the specification.
”!7 ・yn/cnf Correct to Jl.

(Middle) Correct the entry "r 5 kglcn" in the 5th line from the bottom of page 8 of the specification to "5 kgl nl/cit."

(c) Details'? '! No. 9, lines 5-6 (7) [5k!
7/C++ Correct the mouth to ``5 kg+ m, /cA j.

2) Details 2) Page 9, line 6, “3.5 kgl (27J
f "3.5 kg・nL/cnl, correct to j.

(E) Details? In the first column of Table 4 on page 12 of I4, [I <g/cn't, ) J is replaced by "Impact value (kl?
-nt/aj) JI Ic correction.

(to) [MgC1IJ7M on page 15, line 7 of the specification]
p; Corrected to C1,2Jl.

(G) In the second row of the stress corrosion cracking test column in Table 5 on page 14 of the specification, [42% MgC]-J is replaced with "42% MgCl2 j
Correct to.

Claims (1)

[Claims] (1) c: 0.02 or less, N: 0.02
Below the section, st; C1, below the section 5, Mn; 0. !
5% or less, Cr; 18-25%, M. ; O15~2.0%, Nb; υ, 2~0.6 ratio, Al
; 0.1-0.3 qI), V ; U, 1-0.5
A welding wire for high-purity +1 elite stainless steel with excellent weldability V'c and 50 Ajt of impurities. f2) c; 0.02 or less, N; 0. []
22% or less Si: 0.5 or less, Mn: 0.5
4 or less, Or; 1B ~25%, MO; 0.5 ~
2.0%, Nb; 0.2-0.6, Al; 0
．． 17-0.3%, V; 0.1-0.5%, RB
M; O, OU5-0.2, and 50≦
A welding wire for high purity +1 ferritic stainless steel that satisfies -Nb-j-η≦90 and has excellent weldability, the remainder being Fe and unavoidable impurities.