JPS6016319B2 - Composite wire for non-magnetic steel welding - Google Patents

Description

Detailed Description of the Invention The present invention provides a composite material that can be efficiently MIG-welded without causing weld defects such as weld cracks, blowholes, and bits when non-magnetic steel is used as the welding base material. It concerns wires.

Non-magnetic steel is copper that has an austenitic structure and is not affected by magnetism, and usually has a magnetic permeability of 1.5 or less, and is made of copper that must not disturb the magnetic field caused by permanent magnets or electric current. Applies to location. Specific examples of its application include mechanical parts such as television electron guns, gyro compasses, binding wires, crankshafts for seabed minesweeping, and end rings for turbine power generation and induction power generation.
There are quite a number of usage examples where welding is not required. However, since there are very few examples of applying welding to non-magnetic steel, research on non-magnetic molten bale materials has lagged significantly behind. That is, examples of material standards for non-magnetic steel forgings and plates include ASTM A289-6m (temporary standard for alloy steel forgings for non-magnetic retaining rings of generators), VDEhSEW390-6.
Although there are various standards such as No. 1 (non-magnetic steel), there are no specific regulations for composite welding materials for non-magnetic steel.

This is because there is relatively little demand for welding materials for non-magnetic steel, and in some cases 18Mh-1 R-based coated arc welding wire and solid wire skin G wire are used for hard facing purposes. This is because it is only used as a welding material for overlay welding, dissimilar metal welding of high Mn steel and carbon steel, or high Mh steel rail crossing welding. The inventors of the present invention have focused on the above-mentioned circumstances and have conducted intensive research with the aim of establishing a welding material that can efficiently weld non-magnetic steel while retaining its special properties.

As a result, the composition of the composite wire, which is conveniently used especially for skin G welding, was determined from the Schaeffler structure diagram (Anton El Schaeffler: Metal Progress, 1st group G sheep November S
．． 680, Satoshi 01B), the above objective can be achieved if the composition is defined taking into account the transition from molten wire to weld metal, assuming that it has Ni equivalent and Cr equivalent that will form an austenitic structure. It was confirmed that this could be accomplished successfully, and Shigeru was able to successfully complete the present invention. That is, the composite wire for non-magnetic steel welding according to the present invention is 0.00% based on the total weight of the composite wire. Neck weight% (hereinafter simply abbreviated as %) or less of C, 5 to 25% of Mh, 20% or less of Ni, 2% or less of Si, and 17% or less of Cr are each included as essential components, and the Ni equivalent and The Cr equivalent satisfies the following formula, and when the Cr equivalent is 17.6 or less, the Ni equivalent>-
0.8 x C equivalent + 25.3 When Cr equivalent exceeds 17.6, Nj equivalent > 1.1 x Cr equivalent - 0.8 However, Ni equivalent = 0. Disaster elbow i (%) 129.1 x C (%) 10
．． 485 x Mn (%) Cr equivalent = 0.9 r (%) 10
．． 97Mo (%) 10.75×Si (%) 10.3XC
%) Furthermore, the main point is that the flux content ratio in the composite wire is suppressed to 50% or less.

In order to achieve the purpose of the present invention, the wire component must provide a deposited metal with a magnetic permeability of 1.5 or less, and in order to stably obtain a low magnetic permeability, it is necessary to The structure must be austenitic. Regarding this point, Schaeffler's structure diagram is known, which confirms the relationship between the Ni equivalent and Cr equivalent in welded stainless steel and the metal structure. That is, FIG. 1 shows a diagram of the structure. In the figure, F' indicates a ferrite structure, M indicates a martensitic structure, and A indicates an austenite structure. As is clear from Fig. 1, in order to obtain a weld metal with an austenitic structure, the Ni equivalent must be set on a straight line a (i.e. -0.8 x Cr equivalent + 2) below the Cr equivalent of 17.6.
5.3), and if the Cr equivalent exceeds 17.6, the Ni equivalent should be set to a value larger than the straight line b (i.e. 1
．． 1×Cr equivalent −8.0). In other words, by using a composite wire that provides a deposited metal that satisfies the above relationship, it is possible to obtain a nonmagnetic deposited metal that is the forebank of the present invention. However, in order to achieve the purpose of the present invention, the above-mentioned requirements alone are still insufficient; the weld metal must have sufficient physical properties such as yield strength, tensile strength, and elongation, and must be free from weld cracks, blowholes, bits, etc. It must be possible to ensure excellent workability while preventing welding defects.

Taking these circumstances into consideration, the present inventors investigated the component composition of the composite wire in more detail and found that at least C, Mn, Si, Ni, and Cr must be contained as essential components in the entire paper composition of the composite wire. Moreover, the content of these essential components is the sum of the content in the casing and the content in the flux, C≦0.8%, 5≦Mn25%, Nj≦2
It was confirmed that the conditions of SiS: 0%, SiS: 2%, and CrSI: 7% must be satisfied. The reasons for specifying the above-mentioned essential components and determining their content will be explained below.

First, even in a small amount, C has the effect of increasing the mechanical strength, particularly the yield strength and tensile strength, of the weld metal, and this effect is particularly noticeable when the Mn composition is low.

However, care must be taken as the ductility will be extremely reduced if the content in the entire wire exceeds 0.8%. This can be confirmed by the examples shown in Table 1 below. The structures of the molten metals obtained by using these wires were all austenitic, and their physical properties are also listed in Table 1. Table 1 (0 content and physical properties of weld metal) Mn is an essential component to prevent weld cracking of weld metal, and also has the effect of increasing yield strength and tensile strength, so it is included in composite wire components. It is necessary to contain at least 5% or more.

However, if the content exceeds 25%, the yield strength and tensile strength tend to decrease, furthermore, welding fume increases and the conformability of the deposited metal decreases, which is not preferable. This can be confirmed by the experimental examples shown in Tables 2 and 3 below. The structure of the weld metal obtained by using these wires is all austenitic,
Table 3 also lists their physical properties. Table 2 (Mn
Table 3 (Mn content and physical properties of weld metal) Si stabilizes the arc, prevents bits and blowholes, and even improves the base material of the weld metal, although at a very small amount. It is an essential ingredient to improve familiarity with the skin.

However, if the content exceeds 2% in the total composite wire, the arc becomes rather unstable, spatter increases, and workability decreases, which is not preferable. Ni is an essential component for forming an austenitic structure, stabilizing the structure, and ensuring nonmagnetism, and also has the effect of increasing the ductility of the deposited metal.

However, if it is contained in a large amount exceeding 20% in the entire composite wire, the cracking susceptibility of the weld metal will significantly increase, which is not preferable. Cr, like C and Mn, has the property of improving the tensile strength of weld metal, and also has the property of improving corrosion resistance and heat resistance.

Therefore, it is necessary to add an appropriate amount of Cr to ensure particularly excellent corrosion resistance and heat resistance. However, if the Cr content is too high, workability deteriorates, so it should be kept at 17% or less. The effect of adding Cr can be confirmed by the experimental examples shown in Table 4 below. The structures of the weld metals obtained by using these wires were all austenitic, and their physical properties are also listed in Table 4. Table 4 (OR content and physical properties of weld metal) The composite wire of the present invention requires the above-mentioned components, but can also contain an arc stabilizer and the like if desired.

The present invention also uses a small amount of S, which acts as an arc stabilizer.
Although i is included as an essential component, a composite wire composed only of alloying elements has somewhat poor arc stability, and depending on welding conditions, may cause spatter, bits, flow holes, poor fusion, etc.

Therefore, when putting the composite wire of the present invention into practical use, it is desirable to use an appropriate amount of arc stabilizer. Examples of the arc stabilizer include silicates containing Na, K, and Li, oxalates, and fluorides, among which NaF, sodium oxalate, feldspar, potassium glass, LiF, and the like are particularly preferred. Metallic magnesium also has the same effective effect as the above-mentioned stabilizer. However, if too much arc stabilizer is added, the amount of slag generated during welding will increase and workability will be reduced, so even if it is added, the content should be kept to 3% or less based on the entire wire. . Furthermore, in the present invention, in addition to the above-mentioned essential components contained in the entire wire, N.
．． 3%, MoS4%, NbS2%, V≦4%, Ti≦1
．． It is also possible to contain W≦4%. That is, since N has the same austenite forming ability as C,
It is effective to contain a small amount, but if it is too large, blowholes are likely to occur, so the content should be less than 0.3%. Like Cr, Mo and W have the ability to form ferrite and are effective in improving strength, but if the content is too high, the cracking susceptibility of the weld metal increases, so both should be added at 4%.
It should be kept below.

Like Si, Nb and Ti act as deoxidizers and have ferrite formation, but if Nb exceeds 2% or T
If i exceeds 1%, the stability of the arc will be impaired and the sensitivity to cracking will increase, so even if it is added, it should be kept below the above-mentioned content.

V is effective as an auxiliary element for improving the strength of weld metal, but too much V increases cracking susceptibility, so it should be kept at 4% or less. Furthermore, in the present invention, the flux rate must be 50% or less.

However, if the flux rate exceeds 50%, the flux will leak out of the coated metal during manufacturing, causing problems such as wire breakage, making it difficult to manufacture a composite wire with stable quality. In other words, composite wire is generally made by rolling a steel strip in the width direction, filling the grooves with flux, and then rolling the steel strip further to seal in the flux. The larger the amount, the thinner the casing becomes. Therefore 1.2 ribs ◇
If you try to increase the flux rate for small diameter wires with skin G, which often have 1.6 ribs or ◇, the casing will become extremely thin, making it difficult to withstand general wire drawing, and the casing may break during wire drawing. Accidents such as breakage and breakage are likely to occur, and in the end, the upper limit of the flux rate was set at 50% for manufacturing reasons. The welding method to which the composite wire of the present invention is applied is MIG.
The reason for limiting it to welding is as follows.

That is, skin G welding involves welding while shielding the arc atmosphere with an inert gas, and the composite wire undergoes a metallurgical reaction at an extremely high rate of welding during the welding process. Therefore, since the composition of the composite wire becomes almost the same as the composition of the weld metal, by accurately adjusting the composition of the composite wire, weld metal with a desired composition can be obtained. Incidentally, in submerged arc welding, etc., the dispersed flux also participates in the metallurgical reaction during the welding process, so the compositions of the welding wire and the resulting weld metal do not necessarily match.
In particular, in the present invention, the Nj equivalent and Cr equivalent are strictly set in order to make the weld metal an austenitic structure, and the content of essential components is strictly specified in order to ensure adjacent mechanical properties. If the component composition changes during the welding process, the object of the present invention may not be achieved. From these considerations, in the present invention, the skin G welding method, which has a high rate of welding during welding, is selected. In this case, the shielding gas is pure Ar or pure H.
An inert gas such as e may be used alone, but from the point of view of economy or to stabilize the arc, up to about 50% of the gas may be replaced with CO2, or up to about 10% of the gas may be replaced with O2. It is also effective to use a
Although the present invention is roughly constructed as described above, the key point is to ensure a non-magnetic weld metal with an austenitic structure by specifying the Ni equivalent and Cr equivalent of the entire composite wire composition, and to determine the types of essential constituents. By specifying the content and content, it has become possible to secure a weld metal with excellent mechanical properties without welding defects and with excellent workability after melting, making it suitable as a welding material for non-magnetic steel materials. The significance of establishing this technology is enormous.

Next, examples of the present invention will be shown, but the following does not limit the present invention like the embodiments described in the claims, and it is of course possible to make appropriate changes in accordance with the spirit of the above and below. included in the scope of the invention.

However, in the following examples, the content of each component in the entire composite wire refers to a value calculated using the following formula.

wa = Fax K Rate (%) K: Flux rate Examples 1 to 5 Using a composite wire with the composition shown in Table 5, multilayer welding of non-magnetic stainless steel was performed under the conditions shown in Table 6, and the results shown in Table 7 were obtained. I got it.

Table 5 *1: Mild steel composition O Mn Si P S
(Many) 0.04 0.4 0.1 0.015 0
-013*2: Alloy steel composition O Mn Si P
S 0r (%) o. o6 0.6 0.4
0.015 0.008 17 *3: Sodium fluoride, *
4: Metallic Mg, *5: Potassium glass, *6: Sodium oxalate.

Table 6 Table 7 *1. To Taeho.

Kori of Kukawa is ○: 97 leopard, Mn: 97 grandchild, Si:
60 Torture, Ni: 98, 0r: 96*. Table 5~
As is clear from Table 7, when skin-circle welding is performed using the composite wire of the present invention, the composition of the composite wire almost remains the same as the composition of the weld metal. The obtained weld metal was a non-magnetic material with an austenitic structure, had excellent mechanical properties, and could be smoothly welded without causing any welding defects.

[Brief explanation of the drawing]

FIG. 1 is a Schaeffler's structural state diagram, and FIG. 2 is a diagram showing the joint shape and layering method employed in the welding experiment. A. ... Austenite structure, M... Martensitic structure, F... Ferrite structure. Figure 1 Figure 2

Claims (1)

[Claims] 1. A composite wire used for MIG welding non-magnetic steel, the composition of which is 0.8% by weight based on the total weight of the composite wire (hereinafter simply abbreviated as %). ) below C
, 5-25% Mn, 20% or less Ni, 2% or less S
i, contains 17% or less of Cr as an essential component, and the Ni equivalent and Cr equivalent satisfy the following formula, and when the Cr equivalent is 17.6 or less, Ni equivalent > -0.8 x Cr equivalent +25.3Cr equivalent is 1
When exceeding 7.6, Ni equivalent > 1.1 x Cr equivalent - 8.
0 However, Ni equivalent = 0.98 Ni (%) + 29.1 × C (%) +
0.485 x Mn (%) Cr equivalent = 0.96 Cr (%)
+0.97Mo(%)+0.75×Si(%)+0.3
×Cb (%) A composite wire for welding non-magnetic steel, characterized in that the flux content ratio in the composite wire is further suppressed to 50 or less.