Test method for evaluating undercut sensitivity of band electrode submerged arc surfacing flux

Abstract

The invention discloses a test method for evaluating band electrode submerged arc surfacing flux undercut sensitivity, which comprises the following steps: designing a systematic test, and clearly finding out critical welding heat input with the undercut number of 0 by changing welding voltage, welding speed and welding current, accurately controlling welding heat input, counting the corresponding relation between the undercut number and heat input and drawing a curve graph; the undercut sensitivity of the welding flux is quantified through the critical heat input, the critical heat input serves as a core index, the lower the critical welding heat input is, the lower the undercut sensitivity of the corresponding welding flux is, the undercut sensitivity of different welding fluxes can be quantitatively evaluated, data are visual, the transition from qualitative welding flux evaluation to quantitative welding flux evaluation is achieved, and the blank in the technical field is filled. The method has remarkable practical value in research, development and application of the welding flux.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of welding, and particularly relates to a test method for evaluating the edge biting sensitivity of a flux for strip electrode submerged arc surfacing. BACKGROUND

[0002] Submerged arc welding is a method of welding in which the arc is burned under a layer of flux. Its inherent advantages of stable welding quality, high welding productivity, no arc light and little smoke make it the main welding method for important equipment parts and structural parts such as pressure vessels, pipe sections, box beams, nuclear power and the like.

[0003] The process of submerged arc welding mainly includes edge biting sensitivity, weld flatness, deslagging performance, weld bead, and pressure pit, etc. The edge biting sensitivity is the key to the forming quality of the weld, which is related to the performance of the welding material itself in addition to the welding process parameters itself. In actual engineering applications, the improvement of the edge biting of submerged arc welding is mainly realized by adjusting the welding parameters. The process research on the edge biting sensitivity of the flux itself is mainly conducted by the flux manufacturers, which is generally qualitative evaluation without quantitative research.

[0004] Chinese patent CN103542819A discloses a detection and quality determination method for the surface morphology of a strip steel weld. A linear laser is used to scan the surface of the weld, and the weld bead height, depression, edge biting and misalignment are obtained by calculation according to the data obtained by scanning, so as to determine the quality of the weld and realize continuous evaluation of the surface morphology quality of the weld. The patent focuses on the comprehensive evaluation of the surface forming quality of the weld, and is not an evaluation of the flux itself. SUMMARY

[0005] The present application aims to provide an evaluation method for the edge biting sensitivity of a flux for strip electrode submerged arc surfacing, which directly compares the edge biting tendency of different fluxes by taking the critical heat input as the core index. The lower the critical welding heat input is, the lower the edge biting sensitivity of the corresponding flux is. The sensitivity of the flux itself to produce edge biting is quantitatively determined, and the product formula can be optimized by the flux manufacturers through the standard method, thereby shortening the research and development cycle.

[0006] To achieve the above purpose, the technical scheme of the present application is as follows:

[0007] A test method for evaluating the edge biting sensitivity of a flux for strip electrode submerged arc surfacing, comprising the following steps:

[0008] 1) Preparing the welding materials for submerged arc surfacing, including a submerged arc welding machine, a welding strip, a flux and a base plate;

[0009] 2) on the substrate, during the welding process, the welding heat input is changed by adjusting the welding voltage, welding current or welding speed, two welds are obtained under one welding heat input condition, the weld overlap width is 8-12mm, and the weld length is 280-320mm; the weld length is kept consistent under different welding heat inputs;

[0010] The welding voltage and welding speed are kept constant, the welding heat input is changed by adjusting the welding current, or the welding current and welding speed are kept constant, the welding heat input is changed by adjusting the welding voltage, or the welding current and welding voltage are kept constant, the welding heat input is changed by adjusting the welding speed;

[0011] The above operation is repeated by changing different fluxes;

[0012] 3) the number of weld edge bites and the welding heat input of different fluxes under the heat input condition are counted in step 2), and the relationship diagram of the number of weld edge bites and the welding heat input of different fluxes is drawn;

[0013] 4) the critical welding heat input of different fluxes with 0 number of weld edge bites is found out through the relationship diagram of the number of weld edge bites and the welding heat input, and the smaller the critical welding heat input is, the lower the sensitivity of the corresponding flux to weld edge bites is.

[0014] Preferably, in step 2), the welding heat input is changed by 0.2-0.5kJ / min each time.

[0015] Preferably, the flux is NFC690, the substrate is SA5083, and the welding strip is EQNiCrFe-7A.

[0016] Preferably, the welding voltage is 26-32V.

[0017] Preferably, the welding current is 650-850A.

[0018] Preferably, the welding speed is 150-220mm / min.

[0019] The present application designs a systematic test, the welding heat input is accurately controlled by changing the welding voltage, welding speed and current, the welding heat input is changed by 0.2-0.5kJ / min each time, if the welding heat input is changed too much each time, the critical heat input without weld edge bites cannot be found, and if the welding heat input is changed too little each time, too much experimental data is obtained, which increases the workload and has no practical significance.

[0020] Corresponding relationship between the number of undercut and the welding heat input is counted, a curve graph is drawn, the critical welding heat input of the number of undercuts being 0 is found out, the sensitivity of the flux to the undercut is quantified through the critical heat input, the undercut tendency of different fluxes is directly compared by taking the critical heat input as the core index, and the lower the critical welding heat input is, the lower the sensitivity of the corresponding flux to the undercut is.

[0021] When the undercut is evaluated, the present application strictly stipulates the length of the welding bead (280-320mm), the width of the overlap (8-12mm) and the number of the welding bead (two), so as to eliminate the artificial error.

[0022] Compared with the prior art, the present application has the beneficial effects that:

[0023] The prior art uses the process test to qualitatively judge whether the flux is qualified, depends on the subjective experience, qualitatively improves the undercut problem by adjusting the welding parameters, and cannot quantitatively compare across manufacturers.

[0024] The present application finds out the critical welding heat input of the number of undercuts being 0 through the relationship graph of the number of undercuts and the welding heat input of different fluxes, the smaller the critical welding heat input value is, the lower the sensitivity is, the sensitivity of different fluxes to the undercut can be quantitatively evaluated, the data is intuitive, the comparison is obvious, and the sensitivity of the flux to the undercut can be more accurately reflected. The present application solves the leap from the qualitative to the quantitative of the flux evaluation through the unique test design and the quantitative standard, fills the blank in the technical field, and has significant practical value for the research and application of the flux. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 It is the relationship graph of the welding heat input and the number of undercuts of different fluxes in Example 1;

[0026] Figure 2 It is the relationship graph of the welding heat input and the number of undercuts of different fluxes in Example 2. DETAILED DESCRIPTION

[0027] The present application will be further described below in combination with the embodiments and the drawings.

[0028] Example 1

[0029] A test method for evaluating the undercut sensitivity of the electrode flux for the submerged arc surfacing, comprising the following steps:

[0030] 1) Prepare the welding material for the submerged arc surfacing, the base plate for welding is SA5083, the welding strip is EQNiCrFe-7A, the flux 1 is the NFC690 flux of a foreign company, the flux 2 is the NFC690 flux 1 of a domestic company, and the flux 3 is the NFC690 flux 2 of a domestic company;

[0031] 2) On the substrate, build-up welding is carried out, during the welding process, the welding voltage and the welding current remain unchanged, the welding heat input is changed by adjusting the welding speed, two weld beads are obtained under the same heat input, the weld bead overlap width is 10 mm, the weld bead length remains consistent under different welding heat inputs, the weld bead length is 300 mm, and the welding process parameters are shown in Table 1;

[0032] The above operation is repeated by replacing different fluxes;

[0033] 3) The number of edge bites of the weld bead overlap and the welding heat input of different fluxes under the heat input condition are counted in step 2), and the number of edge bites of different fluxes and the welding heat input are plotted, as shown in Figure 1 ;

[0034] 4) The critical welding heat input of different fluxes with the number of edge bites of 0 is found out through the number of edge bites and the welding heat input, and the smaller the critical welding heat input is, the lower the edge bite sensitivity of the corresponding flux is.

[0035] Table 1

[0036]

[0037] It can be seen from Table 1 and Figure 1 that when the welding voltage and the welding current remain unchanged, the welding heat input is changed by adjusting the welding speed, the critical welding heat input of the flux 1, the flux 2 and the flux 3 with the number of edge bites of 0 is 8.4, 8.9 and 7.9 kJ / mm respectively, through comparison, the critical welding heat input of the flux 3 is the lowest, the tendency of producing edge bites is the lowest, the edge bite sensitivity is the lowest, the critical welding heat input of the flux 1 is the second, and the critical welding heat input of the flux 2 is the highest.

[0038] Example 2

[0039] A test method for evaluating the edge bite sensitivity of a flux for submerged arc overlay welding with a strip electrode comprises the following steps:

[0040] 1) The welding materials for submerged arc overlay welding are prepared, the substrate for welding is SA5083, the welding strip is EQNiCrFe-7A, the flux 1 is a foreign SMC company flux NFC690, the flux 2 is a domestic company flux 1 (NFC690), and the flux 3 is a domestic company flux 2 (NFC690);

[0041] 2) On the substrate, build-up welding is carried out, during the welding process, the welding voltage and the welding speed remain unchanged, the welding heat input is changed by adjusting the welding current, two weld beads are obtained under the same heat input, the weld bead overlap width is 8 mm, the weld bead length remains consistent under different welding heat inputs, the weld bead length is 320 mm, and the welding process parameters are shown in Table 2;

[0042] The above operation is repeated by replacing different fluxes;

[0043] 3) Count the number of undercut and the heat input of each flux in step 2), and draw the graph of the number of undercut and the heat input of each flux, as shown in Figure 2

[0044] 4) Find the critical heat input of each flux in which the number of undercut is 0 by the graph of the number of undercut and the heat input, the smaller the critical heat input is, the lower the sensitivity of the flux to undercut is.

[0045] Table 2

[0046]

[0047] From Table 2 and Figure 2 It can be seen that when the welding voltage and the welding speed remain unchanged, the critical heat input of flux 1, 2 and 3 in which the number of undercut is 0 is 8.5, 8.7 and 8.1 kJ / mm respectively by adjusting the welding current to change the heat input, through comparison, the critical heat input of flux 3 is the lowest, the tendency of producing undercut is the lowest, the sensitivity to undercut is the lowest, the critical heat input of flux 1 is the second, and the critical heat input of flux 2 is the highest.

[0048] It is found by comparing Example 1 and Example 2 that the results of evaluating flux 1, 2 and 3 are the same under the condition of changing different welding parameters, which proves that the method described in the application is reliable for comparing the sensitivity of different fluxes to undercut.​

Claims

1. A test method for evaluating sensitivity to edge build-up of a flux for overlaying welding by submerged arc welding, characterized by, The method comprises the following steps: 1) preparing welding materials for submerged arc welding, including a submerged arc welding machine, a welding strip, a welding agent and a base plate; 2) performing overlay welding on the base plate, during the welding process, changing the welding heat input by adjusting the welding voltage, the welding current or the welding speed, obtaining two weld beads under one welding heat input condition, the weld bead overlap width being 8-12 mm, and the weld bead length being 280-320 mm; the weld bead length is kept consistent under different welding heat inputs; keeping the welding voltage and the welding speed unchanged, changing the welding heat input by adjusting the welding current, or keeping the welding current and the welding speed unchanged, changing the welding heat input by adjusting the welding voltage, or keeping the welding current and the welding voltage unchanged, changing the welding heat input by adjusting the welding speed; repeating the above operation by replacing the welding agent; 3) counting the number of the weld bead overlaps and the welding heat input of the weld bead overlaps under different welding heat input conditions of different welding agents in step 2), and drawing a relationship diagram of the number of the weld bead overlaps and the welding heat input of different welding agents; 4) finding the critical welding heat input corresponding to the number of the weld bead overlaps being 0 of different welding agents through the relationship diagram of the number of the weld bead overlaps and the welding heat input, and the smaller the critical welding heat input is, the lower the sensitivity of the corresponding welding agent to the weld bead overlaps is.

2. The test method for evaluating the sensitivity of a flux to edge attack of a strip electrode submerged arc weld overlay according to claim 1, wherein In step 2), the change range of the welding heat input is 0.2-0.5 kJ / min.

3. The test method for evaluating the sensitivity of a flux to edge attack of a strip electrode submerged arc weld overlay according to claim 1, wherein The welding agent is NFC690, the base plate is SA5083, and the welding strip is EQNiCrFe-7A.

4. The test method for evaluating the sensitivity of a flux to edge attack of a strip electrode submerged arc weld overlay according to claim 3, wherein The welding voltage is 26-32 V.

5. The test method for evaluating the sensitivity of a flux to undercutting in submerged arc weld overlay according to claim 3 or 4, characterized in that, The welding current is 650-850 A.

6. The test method for evaluating the sensitivity of a flux to undercutting in submerged arc weld overlaying of a strip as claimed in claim 3 or 4 or 5, wherein The welding speed is 150-220 mm / min.

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