JPS6037290A - Core wire for welding of low temperature steel - Google Patents

Abstract

PURPOSE:To improve remakably hot forgeability with a high NL welding core wire contg. a large amt. of Mo by adding Ca and Mg in combination thereto and limiting the content of Ca+Mg. CONSTITUTION:A core wire for welding low temp. steel is composed to contain, by wt%, 0.0005-0.03 Ca and 0.0005-0.03 Mg and <=0.04 (Ca+Mg). Said core wire contains further 0.01-0.05 C, 0.01-0.5 Ti, 10-25 Mo, <5 W, 3-15 Fe and >65 Ni, contains >=1 kind of 0.01-0.2 Al and 0.001-0.01 B, and contains >=90wt% in total of the above-mentioned components. The tensile strength of the weld metal is further improved if >=1 kind among <5 Cr, <0.5 Si and <3 Mn are incorporated therein.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is applicable to welding core wires for low-temperature steel, particularly structural members of containers or membranes used at extremely low temperatures for liquefied nitrogen, liquefied oxygen, liquefied natural gas, etc. This relates to a welding core wire for low-temperature steel used as a material.

[Prior art]

Conventionally, 9cXN+ steel has been relatively often used as structural members of containers and equipment used at extremely low temperatures for liquefied nitrogen, liquefied natural gas, etc., and is naturally manufactured by acid welding. As a welding material for this cryogenic steel, N has high strength and stable and excellent low temperature toughness at -196℃
I-based alloys are generally made into mm.

The welding material for this system is AWSA5.11]+3N
i 0rli'e 7 5 Ni classified into 1 to 4
-15Or so-called Inconel type and AW8 A5
．． 11 ENiM.

-1, 3, Hastelloy, etc. However, when Inconel welding cores are subjected to submerged arc bath welding, hot cracking tends to occur, and in recent years, Hastelloy welding materials have been widely developed. Japanese Patent Publication No. 49-27732 which has superior tensile strength, excellent low-temperature toughness at -196°C, and good high-temperature cracking t'L sensitivity.
The Hastelloy system has been put into practical use as described in Japanese Patent Publication No. 51-29104, but as the Mo-containing needle becomes higher, the hot forgeability of the welding core wire becomes worse (force and forging yield drops significantly). ◇ [Object of the Invention] In view of the above-mentioned problems, the present inventors conducted numerous studies to improve this problem, and as a result, they added OB and Mg in combination and added Oa + Aig. It has been found that by limiting the amount, hot forgeability can be significantly improved.

The present invention has been made based on the above knowledge, and has good hot forgeability, high tensile strength of bath weld metal, excellent low temperature toughness, and high temperature crackability as a welding core wire for low temperature steel. The present invention provides a new welding core wire with good sensitivity.

[Structure of the invention]

That is, the gist of the present invention is that Oa 0.0005 to 0.03
9 (same as below ERW%), Mu Jg O, 0005 to 0.
03% and (3a + iJg≦0.049f) k satisfied, 00.01 to 0.059, Ti 0.01 to 0
59&, MO10-259g, W 5% or less, F'c3
~15%, containing Ni 65 X or more, and further AA O,
001 to 0.2%, 80.0001 to 0.012, and a total of 90% or more of the above components. be. In addition, if the tensile strength of the weld metal is included, the tensile strength of the weld metal is further improved, and within this range, no deterioration in low-temperature toughness is observed. [Operation] The present invention will be explained in detail below. Note that the percentages for the following ingredients are all based on 9g of heavy weight.

Oa and Mg are components that completely improve the deterioration of hot forgeability due to addition of MO. For example, Figure 1 shows the effect of Oa and MgO addition on the forging yield rate. However, (4) is (
Bl Δ(g addition amount is 0.001%, (Cu u M
g (7,J The amount of addition is o, 01
sK 71[7(il) (A) 'c 取Keu, CB
) l (C1) l fD) , (!-% VC# manufacturing yield rate is significantly improved with the addition of Oa, for example, when the addition of Ca is 0.01%, the forging yield p rate is approximately 90X
Ic reaches. However, in the case of (A) without the addition of R and ig, no significant effect was observed even when Oa was added. Similarly, in the case where there was no Oa filler, no significant effect on improving the forging yield was observed even if Mg was increased. In addition, Oa is less than 0.0005X, M
g is 0. When OOO was less than 5%, no effect was observed even if the above-mentioned encapsulation addition was performed. On the other hand, Oa is 0.
If Mg exceeds 0.03%, the weld metal becomes less sensitive to hot cracking, and if Mg controls 0.03%, slag is likely to occur in 'I'IQ welding. Therefore, Oao, 0005
-0.03%, Mg 0.0005-0.03%. However, the total amount of combined addition of OB and Mg is 0.04
If it exceeds 9, the elongation of the weld metal will drop sharply, so the upper limit was set at 0.04%.

C increases the strength of the weld metal, but if it is less than 0.01%, it has no effect, and if it exceeds 0.059K, the low temperature U properties deteriorate. Therefore, O T1, which is specified at 0.01-0.05%, acts as a deoxidizing agent, further refines the crystal grains of the weld metal and increases the strength, but if it is less than 0.01'h, it is ineffective. If it exceeds 0.5%, it will damage the submerged arc weld metal,
The sticking of the slab gets worse. Therefore, Ti is 0.0
It was defined as 1 to 0.5%.

Mo prevents cylinder temperature cracking during welding and further increases the strength of the weld metal. However, if it is less than 10%, the above effect is not observed, and if it exceeds 25CXfc, the low temperature toughness of the molten metal will deteriorate.
In addition, hot forgeability also deteriorates significantly. Therefore, llo was defined as 10 to 25%.

The strength of the wrought weld metal is increased by η, but if it exceeds 5%, the low-temperature toughness deteriorates and at the same time, the hot forgeability deteriorates significantly. Therefore, O Fe specified at 5% or less has an effect on the cracking resistance and low-temperature toughness of the weld metal, but it has no effect when it is less than 3 (X), and when it exceeds 15%, the strength of welded part 1.1 decreases. Therefore, Fe was specified to be 3 to 15 Ga.

Ni is required for low temperature use (65% or more in order to ensure the low temperature toughness of the 'A weld zone).

For the above ingredients, /L# 0.001-0.2%, BO
, OOO1 to 001%, the joint performance of the welded part will be further improved.

fart! -"Acts as a deoxidizer and also increases strength, but 0
, 0. Less than 196% has no effect, and more than 0.02% increases hot cracking susceptibility. Therefore, o, o o i~
It was defined as 0.2CX. B improves the bending ductility of weld metal, but if it is less than 0.000.197, it has no effect.
．． If it exceeds 0.01%, hot cracking susceptibility increases. Therefore, B was defined to be 0.0001 to 0.01%.

However, if the total of the above components is less than 90%, the strength will be insufficient for bath welding of low-temperature steel, and the low-temperature toughness will also be insufficient.

Therefore, the total of the above components was defined as 90% or more.

Although the minimum essential components of the present invention have been explained above, the welding core wire containing the above components is further
It has been found that the addition of r + Si + Mn i has a positive effect on the bath welding workability and the joint strength of the welded part. Or
If it exceeds 5%, the hot cracking resistance of the weld metal deteriorates, so it is specified to be 5% or less. The same goes for Si [
If the content exceeds 0.5% gold, the hot cracking resistance of the weld metal deteriorates, so it is specified to be 0.5% or less. If Mn exceeds 3%, the pead will become convex and cause defects in the welded joint, so it is specified to be 3% or less. Components other than the above, such as Ta, V,
Zr, Co, Hf, Y, rare earth elements (R
The properties of the welding core wire of the present invention will not be impaired even if each of them is optionally included in an amount of 0.6% or less.

As described above, the present invention is characterized in that in a high Ni-based welding core wire containing a large amount of P islands, by adding Oa and Ng k in combination and limiting the amount of Oa + Mg, the i-forgeability is significantly improved. This was achieved with a wealth of knowledge.

〔Example〕

The effects of the present invention will be illustrated in more detail by Examples below.

4. An alloy having the composition shown in the first embodiment is produced in a vacuum melting furnace, and subjected to forging, rolling, and wire drawing. Otaxφ, 24 Cabinetφ,
A wire with a diameter of 1 or 2 φ was obtained. The coated arc welding rod core wire of 4.0 ■φ, the one of 2.4 ■φ was used as a wire for submerged arc welding, and the one of ■ and two diameters was used as a wire for TIG welding in the experiment. In the first embodiment, w1 to W8 are examples of the present invention,
w9 to W18 show comparative examples. For the coated arc welding rod, raw material powder consisting of 35% limestone, 25% fluorite, 10% barium carbonate, 5% magnesium carbonate, and 10% ferrosilicon was mixed with water glass, and water glass was mixed with water glass. It was applied to Omφ core wire. The coverage rate is 30%, and 4
It was dried at 00°C. For submerged arc welding, 5% limestone;
Raw material powder consisting of 20% silica sand, 15% alumina, 40% fluorite, 10% magnesia clinker, and 2% ferroal silicone is mixed with water glass to produce approximately 500%
Dry at 90% of slack particle size K12 x 1
00 mesh VC tone% was used. 〇For the above welding core wire, using the base material shown in Table 2,
The tensile strength, elongation, low-temperature a property, high-temperature cracking resistance, and welding workability of the weld metals were investigated under the unraveling conditions shown in the table. All test results are shown in Table 4.

Covered arc welding is performed as shown in Figure 2 (a), submerged arc welding is performed using Houki 2.
As shown in figure (b), TIG disconnection is required for 2nd WJ < CI.
As mentioned above, all the steel plates shown in Table 2 were subjected to the bath welding shown in Table 3 for 1 yen.

As shown in Table 4, the test results using welding core wires W-1 to W-8 of the present invention are as follows: hot forgeability, tensile strength of wet weld metal, elongation, impact value, hot cracking resistance, Welding workability was also good. However, W-9 shown as a comparative example has an OB of O,
Hot forgeability was poor when OO was less than 059c, Mg content was 0, and OO was less than 05%.

W-10 has OB added alone (no Mg), 0.003%
, the hot forgeability and hot cracking resistance were poor. W-11 has Mg added alone (does not contain Ca),
Since it exceeded 0.03CX and Ti exceeded 0.05%, the hot forgeability was poor and the slag stuck to the surface.

Since W-12 KE0 exceeded 0.005% and the tooth was less than 65%, the low temperature @ condition deteriorated. Since W-13 has Oa + Mg exceeding 0.045X', the elongation of #weld &M deteriorated. W-14 has less than 10% Mo and 15%
%, the strength of the welding metal chips decreased. W-1
5, Δ10 is 25%? Since the W content exceeded 5%, hot forgeability was poor and low-temperature toughness was reduced. W-1
6 is A! exceeds 0.2%, B exceeds 001%, M
Since n exceeded 3%, the hot cracking resistance was poor and the bead shape became convex. W-17 had poor hot cracking resistance because Or exceeded 5% and Si exceeded 0.5%. In W-18, the total content of the present invention components was less than 90%, and the strength and low-temperature toughness of the weld metal decreased. That is, W-
9 to W-18 are outside the composition range of the present invention, and none of them can achieve the effects of the present invention.

From the above results, it is clear that in the high Ni-based welding core wire containing a large amount of Mo as in the present invention, Ca and M
By adding g in combination, Oa + Mg' (by limiting z)
, a welding core wire with significantly improved hot forgeability and excellent mechanical properties and cracking resistance of the welded part can be obtained.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram showing the influence of Oa and Mg on the forging yield rate, and Fig. 2 (a) l (b) l (C) shows the groove shape and lamination procedure of the steel plate to be welded used in the example. Models 1 to 13 showing Yd contact layering order Agent Patent attorney Masamitsu Akisawa and 2 others

Claims (1)

[Claims] (11Ca O, 0005-0.03 fft,')6
□, MgO, 0005-0.03 heavy needle% and satisfies Oa + Mg≦004% weight%, 00.
01-0.05% by weight, TiO, 01-0.5% by weight,
fV4o 10 to 2521tjt%, W 5% by weight or less, Fe + J to 15 weight%, N165 or more, and further A70.001 to 0.2 iris weight%%80.0001
Welding core wire for low-temperature steel (210a O,0005-0.033f amount) characterized by containing one or more selected from the group consisting of ~0.01% by weight, and containing 90X or more of the above components in total %, MgO
,0005~o, oax amount% and C! ;I+1 odor≦0.04% by weight, satisfied, 0
0.01-0.05% by weight, TiO, 01-0.5M
Amount%, MO10-25% by weight, W 5% by weight or less, Fe
3 to 15 weight 9g, containing Ni65:ii amount% or more, A
,,e O,001~0.2% by weight, 80.0001~
Contains one or more selected from the group consisting of 001% by weight, and further contains 5% by weight or less, SiO, 5% by weight or less, λI
A welding core wire for low-temperature steel, characterized in that it contains at least 9097% of the above components in total, including one or more selected from the group consisting of: n triple needle% or less.