KR20020078205A - A covered electrode for Ni alloy having high Cr content - Google Patents

Abstract

PURPOSE: A covered arc electrode for Ni alloy having high Cr content is provided which secures mechanical properties such as crack resistance and high temperature tensile strength of the high Cr content Ni alloy, does not generates welding defects, and obtains a welding metal having superior weldability at both DC and AC. CONSTITUTION: The covered arc electrode for Ni alloy having high Cr content is characterized in that a covering comprising 12 to 23 wt.% of one or two metal carbonates for the total weight of the covering, 5 to 18 wt.% of one or two metal fluorides, 20 to 32 wt.% of TiO2 and ZrO2, 2 to 5 wt.% of deoxidizer, 35 to 42 wt.% of alloying agent, 3 to 7 wt.% of slag producing agent and 2 to 4 wt.% of binder is covered on a core wire of alloy comprising 0.05 wt.% or less of C, 0.50 wt.% or less of Si, 2.5 to 3.5 wt.% of Mn, 0.03 wt.% or less of P, 0.015 wt.% or less of S, 3.0 wt.% or less of F, 0.50 wt.% or less of Cu, 0.75 wt.% or less of Ti, 18 to 22 wt.% of Cr, 2.0 to 3.0 wt.% of Nb, 0.12 wt.% or less of Co, inevitable trace elements of O and N, and a balance of Ni.

Description

A covered electrode for Ni-based high chromium alloys {A covered electrode for Ni alloy having high Cr content}

The present invention relates to a coated arc electrode, and more particularly, to a coated arc electrode suitable for welding nickel-based high chromium alloys.

In general, the nickel-based alloy refers to Inconel 690 alloy (trade name of INCO, Inc.) suitable for high temperature of 300 ~ 350 ℃ used in pressurized water nuclear power plant. Such a nickel-based alloy has a poor melt flow and tends to be convex in welding beads during coating arc welding, resulting in many welding defects such as slag mixing, and welding defects such as pores due to instability of the arc. In order to compensate for this problem, the inconvenience of using direct current as a welding power source could not be solved.

The present invention has been proposed in view of the above problems, not only to ensure mechanical properties such as crack resistance and high temperature tensile strength of nickel-based high chromium alloys, welding defects do not occur during welding, even in direct current as well as alternating current It is an object of the present invention to provide a coated arc welding rod capable of obtaining a weld metal having excellent weldability.

The above object of the present invention by weight, C 0.05% or less, Si 0.50% or less, Mn 2.5 to 3.5%, P 0.03% or less, S 0.015% or less, Fe 3.0% or less, Cu 0.50% or less, Ti 0.75 Less than%, Cr 18-22%, Nb 2.0-3.0%, Co 0.12% or less and inevitable elements containing O and N, the balance of Ni alloy core, metal carbonate to the total weight of the coating 1 or 2 types 12 to 23%, 1 or 2 types of metal fluorides 5 to 18%, TiO ₂ and ZrO ₂ 20 to 32%, deoxidizer 2 to 5%, alloys 35 to 42%, slag generating agent 3 to It is achieved by a coated arc electrode for nickel-based high chromium alloy, which is characterized by coating a coating material containing 7% and a binder 2-4% on the core wire.

Hereinafter, the role of the core wire and the coating component of the present invention will be described in detail.

In the present invention, using Inconel 600 (trade name of INCO Co., Ltd.) having a low chromium content as a core wire improves workability such as drawing and cutting, and especially Inconel 600 has higher thermal conductivity than Inconel 690, which is widely used in the art. It is possible to prevent rod phenomenon generated during welding. That is, the composition of the core wire used in the present invention is by weight, C 0.05% or less, Si 0.50% or less, Mn 2.5 to 3.5%, P 0.03% or less, S 0.015% or less, Fe 3.0% or less, Cu 0.50% or less, It contains 0.75% or less of Ti, 18 to 22% of Cr, 2.0 to 3.0% of Nb, 0.12% or less of Co, contains O and N as inevitable elements, and Ni as the balance.

Metal carbonate decomposes during welding to generate CO ₂ gas, which shields the arc atmosphere from the atmosphere to prevent oxidation and nitriding of molten metal and helps maintain a healthy weld metal. CaCO ₃ , MgCO ₃ , It is added in the form of BaCO ₃ and the like. The addition amount is preferably 12 to 23% based on the total weight of the coating material by mixing one or two selected from the above metal carbonate, when less than 12% CO ₂ shielding is insufficient to generate pores At the same time, hydrogen cracking is likely to occur. In addition, if it exceeds 23%, the melting temperature of the produced slag becomes high, thereby reducing the fluidity of the slag, resulting in poor welding workability and poor shape of the weld bead. Therefore, the addition amount of the metal carbonate is preferably added at 12 to 23% by weight of one or two selected from the above metal carbonates.

Metal fluoride helps to remove hydrogen present in molten steel and molten slag, lowers the melting point of slag, increases fluidity and improves slag peelability. Typical metal fluorides include CaF ₂ , BaF ₂ , and MgF. ₂ and the like. It is preferable to select one or two of the above-described metal fluorides and add 5 to 18% of the total weight of the coating agent. If the added amount of the metal fluoride is less than 5%, the slag fluidity becomes poor and the appearance of the beads deteriorates and welding is difficult in the posture position. If the content of the metal fluoride exceeds 18%, the slag fluidity increases so much that the slag leading occurs and the undercut At the same time, the shape of the weld bead becomes poor. Therefore, the addition amount of the metal fluoride is preferably added 5 to 18% by mixing one or two selected from the metal fluoride.

TiO ₂ and ZrO ₂ as a slag forming agent improve the slag fluidity and give gloss to the beads to contribute to good bead formation and at the same time serve as arc stabilizers. However, if the added amount is less than 20%, the effect is insignificant. If the added amount is more than 32%, the slag fluidity becomes excessive and the slag becomes dense and the peelability decreases. Therefore, the amount of TiO ₂ and ZrO ₂ added to the total weight of the coating material It is preferable to set it as 20 to 32% with respect to.

The deoxidizer is added to enhance the porosity of the weld metal and to improve the tensile strength and toughness, which is the mechanical performance of the weld metal. Examples of the deoxidizer include Ti, Mn, Mg, Al, Si, Cr, and the like. If it is less than 2% of the total weight, the effect is insignificant, and if it exceeds 5%, the work deteriorates due to excessive generation of pores, spatters, and welding fumes due to excessive deoxidation. Therefore, the deoxidizer is preferably added at 2 to 5% based on the total weight of the coating agent.

The alloying agent is an additive used to alloy all the components of the coating to act as a single component. If the amount is less than 35% of the total weight of the coating, the alloying ability is insufficient. Workability deteriorates. Therefore, it is preferable to add 35-42 weight% of alloying agents with respect to the total weight of a coating agent.

Slag generators include biotite, feldspar and talc, and these slag generators contribute to the formation of sufficient slag to create a good bead shape. When the added amount is less than 3% of the total weight of the coating agent If the slag is not produced sufficiently, poor beads are formed, and if it exceeds 7%, excessive slag is formed to thicken the encapsulation, causing the beads to sag or the slag to cover the molten paper excessively. Therefore, it is preferable that the addition amount of the slag generating agent is 3 to 7% of the total weight of the coating agent.

The caking additive uses water glass as an additive used to adhere the coating material to the core wire. Examples of water glass include sodium silicate, carry silicate and the like, which may be used alone or in combination. If the added amount is less than 2% with respect to the total weight of the coating agent, the adhesion effect is insignificant, and if it exceeds 4%, the coating agent is not uniformly applied to the core wire. Therefore, it is preferable that the addition amount of a caking additive shall be 2 to 4% with respect to the total weight of a coating agent.

Hereinafter, more detailed welding characteristics will be described through examples of the coated arc electrode of the present invention having the components and contents as described above.

In the present invention, as mentioned above, Inconel 600 was used as the core wire, and the composition of the coating material applied on the core wire was different from that shown in Table 1 to perform a welding test. The welding work conditions were evaluated by AC and DC power supply. The welding current intensity was 120 ~ 200A depending on the welding posture, and the welding posture was downward, upward, upward, horizontal and horizontal fillets. Welded longitudinally. The welding test was carried out as described above, and the result was judged to be 26 or more points out of 30 points out of the total points given from 1 to 5 points per item. The results are shown in Table 2, ◎ is evaluated as 5 points, ○ 4 points, ◇ is 3 points, △ is 2 points, 평가 is 1 point.

division Metal carbonate Metal fluoride TiO ₂ and ZrO ₂ Deoxidizer Alloy Slag generator Payment Example One 16.0 5.0 30.0 4.0 37.0 5.0 3.0 2 15.5 18.0 20.0 3.5 35.0 5.0 3.0 3 23.0 10.0 22.0 2.5 36.0 3.0 3.5 4 18.0 8.0 20.0 2.0 42.0 7.0 3.0 5 12.0 13.0 28.0 2.0 38.0 4.0 3.0 Comparative example 6 5.0 18.0 23.0 4.0 42.0 5.0 3.0 7 8.0 17.0 25.0 4.0 38.0 5.0 3.0 8 27.0 7.0 21.0 3.0 36.0 3.5 2.5 9 26.0 6.0 22.0 3.0 37.0 3.0 3.0 10 24.0 3.0 25.0 3.0 37.0 5.0 3.0 11 22.0 4.0 23.0 5.0 36.0 7.0 3.0 12 11.0 22.0 21.0 3.0 36.0 4.0 3.0 13 12.0 21.0 22.0 4.0 35.0 3.0 3.0 14 21.5 15.0 18.0 3.0 36.0 3.0 3.5 15 23.5 12.0 15.0 3.0 40.0 3.5 3.0 16 11.0 6.0 37.0 4.0 36.0 3.0 3.0 17 11.0 6.0 38.0 2.0 36.0 4.0 3.0 18 16.0 13.0 25.0 3.0 38.0 2.0 3.0 19 12.0 8.0 22.0 4.0 36.0 15.0 3.0 20 8.0 4.0 34.0 3.0 43.0 5.0 3.0 21 13.0 3.0 37.0 3.0 36.0 5.0 3.0 22 16.0 22.0 14.0 4.0 36.0 5.0 3.0 23 8.0 9.0 37.0 3.0 36.0 4.0 3.0 24 26.0 12.0 15.0 3.0 37.0 4.0 3.0 25 27.0 3.0 24.0 3.0 37.0 3.0 3.0 26 5.0 24.0 25.0 3.0 37.0 3.0 3.0 27 30.0 3.0 17.0 3.0 38.0 6.0 3.0 28 8.0 25.0 18.0 3.0 38.0 5.0 3.0 29 27.0 7.0 12.0 3.0 36.0 12.0 3.0 30 17.0 12.0 16.0 3.0 37.0 12.0 3.0 31 8.0 13.0 23.0 3.0 37.0 13.0 3.0 32 20.0 3.0 22.0 3.0 36.0 13.0 3.0

division Arc sense Bead appearance Slag fluidity Slag peelability Running capacity Melt uniformity Comprehensive Evaluation Example One ◎ ◎ ○ ◎ ◎ ◎ 29 2 ○ ◎ ○ ◎ ○ ◎ 27 3 ◎ ○ ◎ ○ ◎ ◎ 28 4 ○ ◎ ◎ ◎ ○ ○ 27 5 ○ ◎ ○ ◎ ◎ ◎ 28 Comparative example 6 ○ ○ ◇ ○ ◇ ○ 22 7 ○ ○ ◇ ○ ○ ○ 23 8 ○ ◇ △ △ ◎ ○ 20 9 ○ ◇ △ ○ ○ ○ 21 10 ◎ ○ ◇ ◇ ◇ ○ 22 11 ◎ ○ ◇ ◇ ○ ○ 23 12 ○ ◇ △ △ ◇ ○ 18 13 ○ ◇ △ △ ◇ ○ 18 14 ◇ ◇ ◇ ◇ ◇ ○ 19 15 ◇ ◇ ◇ ◇ ◇ ○ 19 16 ○ ◇ ◇ ○ ◎ ○ 23 17 ○ ○ ◇ ○ ○ ○ 23 18 ○ ◇ △ ◇ ○ ○ 20 19 ○ ◇ △ △ ○ ○ 19 20 ○ ◇ △ ◇ ○ ○ 20 21 ○ ○ ◇ ◇ ○ ◇ 21 22 ◇ ◇ △ △ ◇ ◇ 16 23 ○ ○ ◇ ◇ ○ ◇ 21 24 ◇ ◇ △ △ △ △ 14 25 ○ ○ ◇ ◇ ○ ◇ 21 26 ○ ◇ △ Ⅹ ○ ◇ 17 27 ◇ △ △ Ⅹ △ △ 12 28 ◇ △ △ Ⅹ △ △ 12 29 ◇ △ △ Ⅹ △ △ 12 30 ◇ △ △ Ⅹ △ △ 12 31 ○ ◇ △ Ⅹ ◇ ◇ 16 32 ○ ◇ △ Ⅹ ◇ ◇ 16

Example according to the present invention was 27 points or more in the comprehensive evaluation, the welding workability was found to be excellent, but the satisfactory result was not obtained from the comparative example. Comparative Examples 6, 7, and 9 showed that the slag fluidity was inferior as the addition amount of the metal carbonate was outside the proposed range. In Comparative Examples 10, 12, 25 and 26, the addition of metal carbonate and metal fluoride was found to be markedly reduced in slag peelability as an undesirable example. In Comparative Examples 15, 16, 17, 23 and 24, the addition amount of metal carbonate, TiO ₂ and ZrO ₂ exceeded the suggested range, and the slag fluidity and the appearance of beads were poor. In Comparative Examples 21 and 22, the metal fluoride, TiO ₂ and ZrO ₂ did not satisfy the proposed range, and the slag fluidity and peelability were inferior. Comparative Examples 8, 11, 13, 14, 18, 19, 20, 27, 28, 29, 30, 31, and 32 were also poorly evaluated as bead appearance and melt uniformity as examples outside the scope of the present invention. The slag fluidity and peelability were inferior.

That is, it can be seen that the coating material of Inconel 600, which is the core wire adopted in the present invention, exhibits the best performance when the coating agent having the composition ratio proposed by the present invention is used.

According to the present invention, welding defects are not generated even when the nickel-based high chromium alloy is welded, and a welding metal having excellent welding workability can be obtained not only in direct current but also in alternating current. In addition, there is a practical effect of obtaining a weld metal with satisfactory physical properties such as crack resistance and high temperature tensile strength.

Claims (1)

In the coated arc welding rod for nickel-based high chromium alloy, in weight%, C 0.05% or less, Si 0.50% or less, Mn 2.5 to 3.5%, P 0.03% or less, S 0.015% or less, Fe 3.0% or less, Cu 0.50% Hereafter, Ti 0.75% or less, Cr 18 to 22%, Nb 2.0 to 3.0%, Co 0.12% or less, an inevitable element containing O and N, the balance of Ni as the core wire, the coating weight 12 to 23% of metal carbonates, 12 to 23% of metal carbonates, 5 to 18% of metal fluorides, or 2 to 5% of TiO ₂ and ZrO ₂ , 2 to 5% of deoxidizer, 35 to 42% of alloying agent, slag A coated arc electrode for nickel-based high chromium alloys, characterized by coating a coating material containing 3 to 7% of a producing agent and 2 to 4% of a binder to the core wire.