DE202022105492U1 - Apparatus for joining dissimilar copper to metal by pulsed gas tungsten arc welding - Google Patents

Abstract

Apparatus (100) for making a dissimilar copper to metal joint by pulsed tungsten arc welding, the apparatus (100) comprising:
a tungsten inert gas (TIG) welding module (102) for joining two dissimilar metal pairs such as stainless steel (SS) and copper having a defined chemical composition; and
a butt weld module (104) connected to the TIG weld module (102) for void-free welding of the dissimilar metal in the absence of a filler material, with the edge of the dissimilar metal remaining flat, ie forming a 90° angle.

Description

FIELD OF THE INVENTION

The present invention relates to a field of welding and joining of metals. More particularly, the present invention relates to an apparatus for forming dissimilar copper-to-metal joints by pulsed tungsten arc welding and evaluating the properties of the joint formed.

BACKGROUND OF THE INVENTION

Nowadays, the use of different metal combinations in different fields is gaining more and more popularity due to some advanced properties such as weight reduction, energy consumption, etc. Even if the welding of metals and alloys is a well-known subject, the welding of dissimilar metals represents a major scientific and technical challenge that involves the optimization of parameters, the development of processes, the development of materials, etc. Research is intensively engaged in finding solutions to these challenges. Welding processes are selected depending on the characteristics of the dissimilar joint in question and the characteristics of the product desired for the particular application. The dissimilar pairing, i.e. stainless steel and copper, is used in various industries such as nuclear power plants, heavy electronics, steam turbine power plants, automobiles, switchgear, etc. due to its comprehensive properties such as the high thermal and electrical conductivity of copper and the corrosion resistance of stainless steel.

Numerous research papers in the field of TIG welding related to dissimilar materials, microstructural analysis, mechanical strength, finite element analysis, parametric optimization, etc. have been explained by different researchers.

According to one researcher, Velu and Bhat explained the mechanical and metallurgical behavior when welding two dissimilar metals such as copper (UNSC11000) and alloy steel by gas-shielded arc welding (SMAW). They could not find any harmful intermetallic compounds at the weld. They also studied the fracture toughness and fatigue crack growth behavior of bimetallic compact tensile specimens with Mode I cracks. Nickel (Ni) is used in arc welding as a filler metal between copper and stainless steel.

According to another researcher, Liu et al. the connection of Mg alloy and copper by TIG welding with Fe as an intermediate layer. The researcher reported that the oxide formed at the interface between Mg and Fe affects the mechanical properties of the weld.

According to another researcher, Roy et al. the effects of various electrodes such as Inconel (ENiCrMo3), Monel (ENiCu7) and stainless steel (E316L) on commercially available pure copper and 304 stainless steel weldments by gas-shielded arc welding. Defects such as copper nodules and porosity are observed at the weld of 304 stainless steel.

Another researcher, Suresh Kumar et al., studied the microstructure of copper welds with Fe filler metal using the MIG process. Their microstructural analysis reveals the presence of copper globules embedded in the iron matrix.

A comparative analysis of TIG and A-TIG welding of 304L stainless steel was performed by Sutar and Jadhav. The authors suggest that the A-TIG welding process improves the overall quality of the weld.

JP5982652B2 discloses the production of a dissimilar metal connection by the contact of a copper material and an aluminum material.

There are very few works that use pulsed TIG welding for joining like and dissimilar metals.

According to another researcher, Madadi et al. the hardness and dilution ratio for pulsed TIG hardfacing of Stellite 6 (Co base alloy) on carbon steel. she reported that the penetration depth and thinning increase with pulse frequency, but the hardness of the plating layer decreases.

According to another researcher, Yu et al. proposed a wire feed monitoring technique to detect a defect in an Al-Mg alloy by pulsed TIG welding.

According to another researcher, Rajkumar and Arivazhagan studied the role of pulsed current on the welding properties of maraging steel and AISI 4340, an aerospace steel, which is not bonded to the same material. The authors concluded that pulsed TIG welding has superior welding properties in all mechanical and metallurgical aspects and is very reliable for joining dissimilar material combinations. Ramkumar et al. (2015) studied the joining of marine grade (Monel 400) and AISI 904L alloys using ERNiCu-7 and ERNiCrMo-4 filler metals with pulsed tungsten arc welding. The deformation properties of TIG and MIG welded parts are studied by Erichsen tests (Dewangan et al., 2021).

CN102658443B discloses a braze for brazing tungsten-copper alloys and stainless steel and a brazing method.

the US20070181550A1 discloses welding copper with activated TIG welding. In particular, the copper coils of electrical generators are welded.

From the previous review of the literature on TIG welding, it is clear that there is a large research gap in relation to detailed mechanical and microstructural investigations of the fusion zone, the behavior of the process parameters during welding and the parametric optimization for thin sheets. Very few works deal with pulsed TIG welding without filler material for the connection copper - stainless steel AISI 304.

Therefore, there is a need to develop a device for making connections between copper and metal using pulsed tungsten arc welding and to provide the processing industry with useful information about the possibilities of welding two dissimilar sheets (stainless steel 304 and copper) with a pulsed TIG system without supply additional material.

The technical advance disclosed by the present invention overcomes the limitations and disadvantages of existing and conventional systems and methods.

SUMMARY OF THE INVENTION

• Ziel der vorliegenden Erfindung ist es, eine Vorrichtung zum Schweißen unterschiedlicher Verbindungen bereitzustellen;
• Ein weiteres Ziel der vorliegenden Erfindung ist es, die Möglichkeiten des Schweißens von zwei ungleichen (Edelstahl 304 und Kupfer) dünnen Blechen mit einem gepulsten WIG-System ohne Zusatzwerkstoff zu bewerten;
• Ein weiteres Ziel der vorliegenden Erfindung ist es, ein umweltfreundlicheres Herstellungsverfahren bereitzustellen; und
• Ein weiteres Ziel der vorliegenden Erfindung ist es, ein rauchfreies Schweißen zu ermöglichen.

The present invention relates generally to apparatus for making copper to metal joints by pulsed gas tungsten arc welding.

• The aim of the present invention is to provide a device for welding different joints;
• Another object of the present invention is to evaluate the possibilities of welding two dissimilar (stainless steel 304 and copper) thin sheets with a pulsed TIG system without filler material;
• Another object of the present invention is to provide a more environmentally friendly manufacturing process; and
• Another object of the present invention is to enable smoke-free welding.

• ein Wolfram-Inertgas (WIG)-Schweißmodul zum Verbinden zweier ungleicher Metallpaare wie Edelstahl (SS) und Kupfer mit einer definierten chemischen Zusammensetzung; und
• ein Stumpfschweißmodul, das mit dem WIG-Schweißmodul verbunden ist, um das ungleiche Metall in Abwesenheit eines Zusatzwerkstoffs hohlraumfrei zu schweißen, wobei die Kante des ungleichen Metalls flach bleibt, d. h. einen Winkel von 900 bildet.

In one embodiment, an apparatus for making a dissimilar copper to metal joint by pulsed gas tungsten welding, the apparatus comprising:

• a tungsten inert gas (TIG) welding module for joining two dissimilar metal pairs such as stainless steel (SS) and copper with a defined chemical composition; and
• a butt welding module connected to the TIG welding module to weld the dissimilar metal without voids in the absence of a filler metal, leaving the edge of the dissimilar metal flat, ie forming a 90° angle.

In one embodiment, the stainless steel is American Iron and Steel Institute (AISI) 304 SS with a composition of 0.29% silicon (Si), 17.71% chromium (Cr), 0.72% manganese (Mn), 7.13% nickel ( Ni), 0.04% carbon (C) and a balance of iron (Fe).

In one embodiment, the copper has a composition of 99.63% copper (Cu) and 0.37% Si.

In one embodiment, the TIG welding module includes a 1-2 mm straight polarity electrode, a shielding gas flow rate of 5-15 lpm to maintain an inert environment, a constant frequency, and a ramp time of 500 Hz or 0.75 seconds.

In one embodiment, an input module is provided for receiving a plurality of variable welding process parameters, such as peak current, scan speed, and standoff distance, with four levels of variance.

In one embodiment, a calculation module calculates the signal-to-noise ratio and the tensile strength for each level of the input process parameters.

In one embodiment, a quadratic model associated with the calculation module is given a tensile stress regression technique.

In one embodiment, a conformance checking module evaluates a non-linear regression technique with accuracy.

In one embodiment, a macrostructure analysis module analyzes a melt zone to confirm sidewall fusion quality and penetration depth.

In one embodiment, a microstructure analysis module consists of an optical microscope and a surface profiler that analyzes the strength of the weld pool surface both qualitatively and quantitatively, with weld cross-sections obtained by cutting with a wire EDM and subsequent polishing for metallurgical analysis, where Metallurgical specimens are cleaned in an ultrasonic bath and electrolytically etched in a 10% oxalic acid solution at 3 volts for 3 minutes to reveal the microstructure of the weld pool.

In order to further clarify the advantages and features of the present invention, a more detailed description of the invention will be made by reference to specific embodiments thereof illustrated in the attached figure. It is understood that this figure only shows typical embodiments of the invention and therefore should not be considered as limiting its scope. The invention will be described and illustrated with additional specificity and detail with the accompanying figure.

character list

• 1 ein Blockdiagramm einer Vorrichtung zum Herstellen von Verbindungen zwischen Kupfer und Metall durch gepulstes Wolfram-Schutzgasschweißen zeigt.

These and other features, aspects and advantages of the present invention will be better understood when the following detailed description is read with reference to the accompanying figure, in which like characters represent like parts throughout the figure, wherein:

• 1 Figure 12 shows a block diagram of an apparatus for making copper-to-metal connections by pulsed tungsten gas-shielded arc welding.

Those skilled in the art will understand that the elements in the figure are shown for simplicity and are not necessarily drawn to scale. For example, the flow charts illustrate the method of key steps to enhance understanding of aspects of the present disclosure. Furthermore, one or more components of the device in the figure may be represented by conventional symbols, and the figure only shows the specific details relevant to understanding the embodiments of the present disclosure, not to encircle the figure with details to overload, which are easily recognizable to those skilled in the art familiar with the present description.

DETAILED DESCRIPTION

For the purposes of promoting an understanding of the invention, reference will now be made to the embodiment illustrated in the Figure and specific language will be used to describe the same. It should be understood, however, that no limitation on the scope of the invention is intended, and such alterations and further modifications to the illustrated system and such further applications of the principles of the invention set forth therein are contemplated as would occur to those skilled in the art invention would normally come to mind.

Those skilled in the art will understand that the foregoing general description and the following detailed description are exemplary and explanatory of the invention and are not to be taken as limiting.

When this specification refers to "an aspect," "another aspect," or the like, it means that a particular feature, structure, or characteristic described in connection with the embodiment is present in at least one embodiment of the present invention. Therefore, the phrases "in one embodiment," "in another embodiment," and similar phrases throughout this specification may or may not all refer to the same embodiment.

The terms "comprises," "including," or other variations thereof are intended to cover non-exclusive inclusion, such that a method or method that includes a list of steps includes not only those steps, but may also include other steps that are not expressly stated or pertaining to any such process or method. Likewise, any device or subsystem or element or structure or component preceded by "comprises...a" does not, without further limitation, exclude the existence of other devices or other subsystem or other element or other structure or other component or additional device or additional subsystems or additional elements or additional structures or additional components.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one skilled in the art to which this invention pertains. The system, methods, and examples provided herein are for purposes of illustration only and are not intended to be limiting.

Embodiments of the present invention are described in detail below with reference to the attached figure.

1 shows a block diagram of an apparatus (100) for making a joint of dissimilar copper to metal by pulsed tungsten gas welding, the apparatus (100) comprising: a tungsten inert gas (TIG) welding module (102), a butt welding module (104 ), an input module (106), a calculation module (108), a quadratic module (110), a conformance check module (112), a macrostructure analysis module (114), and a microstructure analysis module (116).

The Tungsten Inert Gas (TIG) Welding Module (102) joins two dissimilar metal pairs such as Stainless Steel (SS) and Copper with a specific chemical composition. The stainless steel is American Iron and Steel Institute (AISI) 304 SS with a composition of 0.29% silicon (Si), 17.71% chromium (Cr), 0.72% manganese (Mn), 7.13% nickel (Ni), 0.04 % carbon (C) and the remainder iron (Fe). The copper has a composition of 99.63% copper (Cu) and 0.37% Si. The TIG welding module (102) includes a 1-2 mm straight polarity electrode, a shielding gas flow rate of 5-15 lpm to maintain an inert environment, a constant frequency and a ramp time of 500 Hz or 0.75 seconds.

The butt welding module (104) is connected to the TIG welding module (102) to weld the dissimilar metal without voids in the absence of filler metal, leaving the edge of the dissimilar metal flat, i.e. forming a 90° angle.

The input module (106) for receiving a variety of variable process parameters for welding, such as peak current, scan speed and standoff distance with four levels of variance.

In one embodiment, the invention is analyzed according to the orthogonal array matrix Taguchi L16 (43) with three replicates. A total of 48 samples are therefore welded. All factor levels are equally weighted to ensure balanced experimental design. Table 1: Variable process parameters for welding parameter units levels 1 2 3 4 Peak current (I _P ) amp 80 90 100 110 Welding speed (S) mm/min 90 120 150 180 clearance area (D) mm 0.85 1.00 1.15 1.30

The calculation module (108) calculates a signal-to-noise ratio and tensile strength for each level of the input process parameters. Tensile tests are performed at room temperature on an Instron® 600KN automatic universal testing machine. The entire design matrix with the respective tensile stress results is listed in Table 2. Table 2: Design of experiments matrix with results Run No. IP _{_} S D Tensile Stress (MPa) S/N ratio 1 110 90 0.85 171 44.6599 2 110 120 1.00 170 44.6090 3 110 150 1.15 171 44.6599 4 110 180 1.30 116 41.2892 5 80 90 1.00 237 47.4950 6 80 120 0.85 196 45.8451 7 80 150 1.30 153 43.6938 8th 80 180 1.15 137 42.7344 9 90 90 1.15 278 48.8809 10 90 120 1.30 175 44.8608 11 90 150 0.85 169 44.5577 12 90 180 1.00 152 43.6369 13 100 90 1.30 188 45.4832 14 100 120 1.15 275 48.7867 15 100 150 1.00 189 45.5292 16 100 180 0.85 150 43.5218

There are three types of qualifiers in S/N ratio analysis, namely smaller-the-better, larger-the-better, and nominal-the-better, which depend on the initial responses. In the present study, the tensile stress S/N ratio is chosen according to the “bigger-the-better” criterion in order to maximize the response given in Equation 1. The equation for the S/N ratio for all responses is given as follows: $$\raisebox{1ex}{$\text{S}$}\!\left/ \!\raisebox{-1ex}{$\text{N}$}\right.=-10{\text{log}}_{10}\left({\displaystyle \sum \frac{\raisebox{1ex}{$1$}\!\left/ \!\raisebox{-1ex}{${\text{y}}^2$}\right.}{\text{n}}}\right)$$

where: y = average measured tensile stress
n = number of trial runs

Since the response is based on the bigger the better analysis, the peak values from the chart are the optimal settings to maximize results. The ones from the main action slide The peak setting found in grams is: "Peak current = 100 A, welding speed = 90 mm/min and distance = 1.15 mm." So the optimal combination is "100-90-1.15".

The quadratic module (110) is connected to the calculation module (108) to obtain a tensile stress regression method.

The linear regression equation for tensile stress is given in Equation 2 as follows: $$\text{tensile stress}=\mathrm{375,492}-0.6425\left({\text{I}}_{\text{P}}\right)-0.9092\left(\text{S}\right)-8.1667\left(\text{D}\right)$$

The ANOVA table is used to study the effects of process parameters on maximum weld strength. The confidence level is set at 95% for this model. To check the current regression model, the R ² , the adj. R ² and the standard error calculated from the ANOVA table and presented in Table 3. Table 3: Analysis of variance for S/N ratios source DF ss Adj. MS f P IP 3 9,421 3.1403 3.74 0.080 S 3 34,872 11,624 13.8 0.004 D 3 12,766 4.2552 5.06 0.044 mistake 6 5,042 0.8404 All in all 15 62.101 S = 0.9167 R2 = ^91.9 % R ² (adj.) = 79.7%

The value of "F" indicates the effectiveness of the process parameter on the response. The highest “F” value is obtained for the weld speed at 13.83, which has the greatest impact on the response, followed by distance and peak current. Since the "P" value is below 0.05, which represents the significance of the parameter, the welding speed and distance have a significant value while the peak current has no significant value. The R2 and adj. R2 values obtained from ANOVA, i.e. H. 91.9% and 79.7%, respectively, determine the suitability of the model in relation to the initial responses.

Tabelle 4: Ergebnisse der Konformitätsprüfung für die Zugspannung Optimale Prozessparameter Zugspannung (MPa) Fehler (%) IP S D Voraussichtlicher Wert Experimenteller Wert 100 90 1.15 268 254 5.22 279 4.10 243 9.33 Mittlerer Fehler (%) 6.22 The conformance check module (112) assesses the validation of a nonlinear regression technique with accuracy. The developed device was confirmed to be accurate as the average error percentages are about 6.22%. The percentage error between the value predicted by the model and the experimental result is calculated by Equation 3 as follows: $$\text{errors}\%=\frac{\text{experimental value}-\text{Predicted value}}{\text{Predicted value}}$$

Table 4: Tensile Stress Conformance Test Results Optimal process parameters Tensile Stress (MPa) Mistake (%) IP S D Estimated Value experimental value 100 90 1.15 268 254 5.22 279 4.10 243 9.33 Mean error (%) 6.22

The macrostructure analysis module (114) analyzes a melt zone to confirm sidewall melt quality and penetration depth.

The microstructure analysis module (116) includes an optical microscope and a surface profiler that analyzes the strength of the weld pool surface both qualitatively and quantitatively, measuring the weld cross-sections by cutting with a wire EDM and then polishing for Metallurgical analysis can be obtained by cleaning the metallurgical samples in an ultrasonic bath and electrolytically etching them in a 10% oxalic acid solution at 3 volts for 3 minutes to reveal the microstructure of the weld pool.

The smoothness of the welding zone compared to the base materials is measured with the "VEECO Dektal 150®" stylus profilometer. The total hump of the weld pool varies between 150 µm and 290 µm compared to the base metal level. The trough-shaped area observed on the copper side of the melt zone may be due to uneven temperature distribution and fluid flow direction. Comparing the weld strength to the surface profile data shows that samples 2, 6 and 14 with less troughing (approximately 10-30 µm, which is what ASME standard “B31.1, 136.4.2 (A 2)” is acceptable) near the molten pool on the copper side have a higher tensile stress than the others, i.e. H. 170MPa, 196MPa and 275MPa respectively. Sample 12 with a trough value of 160 µm on the copper side of the weld pool has a tensile stress value of 152 MPa. So, the formation of a trough near the weld pool has a negative impact on the weld strength, as can be seen from the analysis above.

The microstructure analysis is carried out for the different zones of the weld. Copper balls with copper channels can be seen in the weld pool. Dendrites are mainly formed by the diffusion of Cr, Ni, Fe and Cu, leading to intermetallic formation. The unmixed areas are near the melting point on the copper side. The high thermal conductivity and high thermal expansion of copper lead to significant thermal stresses in this area and cracking. It is difficult to see the clear melt line in this image and the degree of intermixing cannot be technically assessed at this point. The uneven boundary between copper and weld metal indicates that the copper has been melted unevenly. Table 5: Elemental composition of selected spectra site feet Cu Cr Mn no S-3 5.09 89.71 1.60 1.39 2.20 S-11 24.69 64.89 8.19 0..46 1.77 S-12 6.71 90.93 0.75 0.45 1.15 S-13 5.20 92.82 0.78 0.42 0.77 S-14 8.96 86.71 2.03 0.45 1.85

Both quantitative and qualitative compositional analyzes are performed using EDS for a few key selected locations in the weld pool structure. Elemental analysis and color map analysis are performed for selected point areas and larger areas, respectively. For the EDS analysis, the weld areas explained in the previous section are taken into account. Spectra 3, 11, 12, 13 and 14 are run through for the point scan. The table shows that with the exception of Spectrum 11, all other selected areas are predominantly copper bearing. The channel-like structure connecting these copper spheres is also copper-bearing, as seen in spectrum 3.

X-ray diffraction analysis is performed on pulsed TIG welded 304 stainless steel and Cu samples to determine the crystal structure and d-spacing of the coupled materials. The crystal plane of y (111) is perceived at 20 theta positions of 43,802 with the highest intensity. The presence of Fe and Cu elements is found in each respective peak. Very low intensity chromium carbide (Cr3C2) is detected at 20 theta positions out of 38,748. The σ-phase forms during post-processing cooling in the chromium-enriched region where upward diffusion of Cr can occur. The amount of δ-Fe formation in the joint depends on the thermal development during welding. Due to the high cooling rate, the δ-Fe content in the joints is higher.

Microhardness is also an indirect indicator of the material's strength properties and also reveals the effects of microstructural heterogeneities. Here the Vickers microhardness (HV) measurements are taken throughout the weld pool, starting with the base material copper and AISI 304 SS at three different depths. The microhardness (HV) of the two base metals shows the smallest deviation compared to the weld zone including the respective HAZ, ie 60-75 and 200-215 for Cu and 304 SS respectively. The microhardness distribution in the weld zone was larger than for copper and lay close to the values of 304 stainless steel. The lowest value was observed in the HAZ of copper compared to other zones.

The sixteen experiments carried out were used for the tensile test in the "INSTRON 600KN®" UTM. The Taguchi design corresponds to the good suitability of the design model. But the design does not clarify the result of the tension from the welding point of view. The tensile stress of the copper is 190 MPa. If the tensile stress of the welded specimen is over 190MPa, then the welding can be accepted. Here, the strain rates for all samples are assumed to be 0.01 mm/min.

Out of sixteen trials, six stress results were close to and above 190 MPa. The failures also occurred in the weld pool and in the area near the HAZ on the copper side. The accepted tensile stress values are 237 MPa, 196 MPa, 278 MPa, 188 MPa, 275 MPa and 189 MPa for test numbers 5, 6, 9, 13, 14 and 15.

The fracture surface morphology of the welded samples is observed from the SEM image taken with the Oxford brand JEOL JSM-6084LV® scanning electron microscope after the completion of the tensile test. The ductile fracture relates to numerous pits on the fracture surface, suggesting that the failure occurs on the bare copper side.

• • Der Erfolg des Schweißens unterschiedlicher Metalle ohne Schweißzusatz kann zu umweltfreundlicheren und nachhaltigeren Fertigungsverfahren führen.
• • Die ANOVA-Tabelle und die Berechnung des Durchschnittsfehlers bestätigen die bessere Eignung des orthogonalen Taguchi-Designmodells für das WIG-Schweißen mit gepulster Welle für SS-Cu-Paarungen.
• • Die Oberseite der geschweißten Proben ist glatt genug, da die mit dem Profilometer gemessene Vertiefung des Schweißbads im Vergleich zum Grundwerkstoff zwischen 120 und 230 µm liegt.
• • Die Bildung einer Mulde in der Nähe des Schweißbades (entweder auf der Seite von SS 304 oder auf der Seite von Cu) hat einen negativen Einfluss auf die Schweißnahtfestigkeit. Der Mindestwert der Mulde führt zu einer höheren Zugfestigkeit.
• • Chromkarbid (Cr3C2) mit sehr geringer Intensität wird an 20 Thetapositionen von 38.748 nachgewiesen, was seine Anwesenheit im Schweißbad bestätigt. Die σ-Phase bildet sich während der Abkühlung nach der Bearbeitung in der chromangereicherten Region, in der eine Aufwärtsdiffusion von Cr auftreten kann. Martensit und Zementit werden bei der XRD-Analyse bei 20 Thetapositionen von 44.175 bzw. 45.054 nachgewiesen.
• • Die Verteilung der Mikrohärte in der Schweißzone ist größer als bei Kupfer und liegt nahe an den Werten von Edelstahl 304. Der niedrigste Wert wird in der WEZ von Kupfer im Vergleich zu anderen Zonen gemessen.
• • Die aktuelle experimentelle Analyse zeigt, dass die Zugspannung akzeptabel ist (sie variiert zwischen 190 und 278 MPa).

A successful weld was made between two dissimilar metals, namely AISI 304 SS and Cu, and the following conclusions were drawn from the investigations:

• • The success of welding dissimilar metals without filler metal can lead to greener and more sustainable manufacturing processes.
• • The ANOVA table and the mean error calculation confirm the better suitability of the orthogonal Taguchi design model for pulsed wave TIG welding for SS-Cu pairings.
• • The top of the welded specimens is smooth enough as the depth of the weld pool measured with the profilometer is between 120 and 230 µm compared to the base metal.
• • The formation of a trough near the weld pool (either on the SS 304 side or on the Cu side) has a negative impact on the weld strength. The minimum value of the trough results in higher tensile strength.
• • Very low intensity chromium carbide (Cr3C2) is detected at 20 theta positions of 38,748, confirming its presence in the weld pool. The σ-phase forms during post-processing cooling in the chromium-enriched region where upward diffusion of Cr can occur. Martensite and cementite are detected at 20 theta positions of 44,175 and 45,054, respectively, on XRD analysis.
• • The distribution of microhardness in the weld zone is larger than that of copper and is close to that of 304 stainless steel. The lowest value is measured in the HAZ of copper compared to other zones.
• • The current experimental analysis shows that the tensile stress is acceptable (it varies between 190 and 278 MPa).

In one embodiment, the frequency and ramp time are held constant at 500 Hz and 0.75 seconds, respectively.

The figure and the preceding description give examples of embodiments. Those skilled in the art will understand that one or more of the elements described may well be combined into a single functional element. Alternatively, certain elements can be broken down into multiple functional elements. Elements from one embodiment may be added to another embodiment. For example, the order of the processes described herein may be changed and is not limited to the manner described herein. Additionally, the actions of a flowchart need not be performed in the order shown; Also, not all actions have to be carried out. Also, those actions that are not dependent on other actions can be performed in parallel with the other actions. The scope of the embodiments is in no way limited by these specific examples. Numerous variations are possible, regardless of whether they are explicitly mentioned in the description or not, e.g. B. differences in structure, the dimensions and the use of materials. The scope of the embodiments is at least as broad as indicated in the following claims.

Advantages, other benefits, and solutions to problems have been described above with respect to particular embodiments. However, the benefits, advantages, problem solutions, and components that can cause an advantage, benefit, or solution to occur or become more pronounced are not to be construed as a critical, required, or essential feature or component of any or all claims.

reference list

100

Device (100) for producing a connection between copper and metal by pulsed tungsten arc welding.

102

TUNGRAM INERT GAS (TIG) WELDING MODULE

104

BUTT WELDING MODULE

106

INPUT MODULE

108

CALCULATION MODULE

110

SQUARE MODULE

112

CONFORMITY CHECK MODULE

114

MACROSTRUCTURE ANALYSIS MODULE

116

MODULE FOR MICROSTRUCTURE ANALYSIS

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• JP 5982652 B2 [0009]
• CN 102658443B [0014]
• US20070181550A1 [0015]

Claims (10)

Apparatus (100) for making a dissimilar copper to metal joint by pulsed tungsten arc welding, the apparatus (100) comprising: a tungsten inert gas (TIG) welding module (102) for joining two dissimilar metal pairs such as stainless steel (SS) and copper having a defined chemical composition; and a butt welding module (104) connected to the TIG welding module (102) for void-free welding of the dissimilar metal in the absence of a filler material, with the edge of the dissimilar metal remaining flat, i.e. forming a 90° angle. device after claim 1 , the stainless steel being American Iron and Steel Institute (AISI) 304 SS with a composition of 0.29% silicon (Si), 17.71% chromium (Cr), 0.72% manganese (Mn), 7.13% nickel (Ni) , 0.04% carbon (C) and the remaining % iron (Fe). device after claim 1 , the copper having a composition of 99.63% copper (Cu) and 0.37% Si. device after claim 1 wherein the TIG welding module (102) comprises a 1 to 2 mm straight polarity electrode, a shielding gas flow rate of 5 to 15 l/min to maintain an inert environment, a constant frequency and a ramp time of 500 Hz or 0.75 s. device after claim 1 , with an input module (106) for receiving a plurality of variable process parameters for welding such as peak current, scanning speed and standoff distance with four variance levels. device after claim 5 , wherein a calculation module (108) calculates a signal-to-noise ratio and the tensile strength for each level of the inputted process parameters. device after claim 6 wherein a quadratic module (110) is connected to the calculation module (108) to obtain a tensile stress regression method. device after claim 6 , wherein a conformance check module (112) validates a non-linear regression technique with accuracy. device after claim 1 wherein a macrostructure analysis module (114) analyzes a melt zone to confirm sidewall fusion quality and penetration depth. device after claim 1 , wherein a microstructure analysis module (116) comprises an optical microscope and a surface profiler that analyzes the strength of the weld pool surface both qualitatively and quantitatively, wherein weld cross-sections are obtained by cutting using a wire EDM and subsequent polishing for metallurgical analysis, wherein Metallurgical specimens are cleaned in an ultrasonic bath and electrolytically etched in a 10% oxalic acid solution at 3 volts for 3 minutes to reveal the microstructure of the weld pool.

Images