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Number of results: 11
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Abstract

This paper discusses issues related to optimising the technological parameters of the process of brazing gold in a vacuum

furnace. An investigation of the brazing process was carried out for materials used in constructing components for aircraft engine

fuel systems. The vacuum brazed material was AMS 5510 stainless steel (in the form of plates and pipes). AMS 4787 (BAu-4) was

used as the brazing filler. In particular, the influence of the method of preparing the surface on solder spreading and the thickness

of the diffusion zone were analysed. The best spreading of solder was obtained for nickel plated surfaces. When the sample surface

was more rough or scratched, the effect of the spreading of solder was limited and the diffusion process of the solder into the base

material became dominant. Moreover, the influence of the brazing temperature on microstructure changes and on interdiffusion

of the AMS 5510 stainless steel/BAu-4 solder system was determined. It was observed that an increase in the brazing temperature

modifies the morphology of the formed joint by forming a massive and rounded phase. Furthermore, an increase in the brazing

temperature enhances the exchange of components.

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Authors and Affiliations

M. Hebda
P. Kaczor
K. Miernik
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Abstract

The article summarizes the theoretical knowledge from the field of brazing of graphitic cast iron, especially by means of conventional

flame brazing using a filler metal based on CuZn (CuZn40SnSi – brass alloy). The experimental part of the thesis presents the results of

performance assessment of brazed joints on other than CuZn basis using silicone (CuSi3Mn1) or aluminium bronze (CuAl10Fe). TIG

electrical arc was used as a source of heat to melt these filler materials. The results show satisfactory brazed joints with a CuAl10Fe filler

metal, while pre-heating is not necessary, which favours this method greatly while repairing sizeable castings. The technological procedure

recommends the use of AC current with an increased frequency and a modified balance between positive and negative electric arc polarity

to focus the heat on a filler metal without melting the base material. The suitability of the joint is evaluated on the basis of visual

inspection, mechanic and metallographic testing.

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Authors and Affiliations

M. Mičian
R. Koňár
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Abstract

Brazing of two dissimilar structural materials; Zircaloy-4 and SS-316L was performed at 900oC under high vacuum conditions. The metallic glass ribbons (Zr55Cu30Al10Ni2Fe3-at. %) of 30 µm thickness, were used as an interlayer. The bonded region was characterized by scanning electron microscope (SEM), energy dispersive spectroscope (EDS) and microhardness testing. The metallurgical bond formation was due to compositional changes in the molten interlayer and later on its subsequent solidification. Assessment of the bonded zone (BZ) revealed three distinct regions (Region-I, Region-II and Region-III). Diffusion transformation was observed in Region-I and Region-III which were interface with base alloys SS-316L and Zircaloy-4 respectively. However, Region-II at the middle of the BZ was composed of isothermally and athermally solidified portions. The highest values of Microhardness were observed in Region-III which was due to the presence of hard phases. Moreover, a crack parallel to BZ was observed in Region-III and was attributed to differential contraction of base alloys during cooling. Maximum shear stress acting on the BZ was calculated and correlated to the brittle phase cracking.

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Authors and Affiliations

A. Munis
Maosheng Zheng
J.I. Akhter
M. Ahmad
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Abstract

This paper outlines issues associated with gas-shielded braze welding of CU-ETP copper with austenitic steel X5CrNi18-10 (1.4301) using a consumable electrode. The possibilities for producing joints of this type using innovative low-energy welding methods are discussed. The paper provides an overview of the results of metallographic and mechanical (static shear test, microhardness) tests for braze welded joints made on an automated station using the Cold Metal Transfer (CMT) method. Significant differences in the structure and mechanical properties are indicated, resulting from the joint configuration and the type of shielding gas (argon, helium).

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Authors and Affiliations

T. Wojdat
ORCID: ORCID
P. Kustroń
A. Margielewska
M. Stachowicz
ORCID: ORCID
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Abstract

This paper introduces an approach for vacuum brazing of niobium-316L stainless steel transition joints for application in superconducting radiofrequency cavity helium jackets. The study takes advantage of good wettability of Ag-Cu-Pd brazing alloy to suppress brittle Fe-Nb intermetallic formation, hence improve the joints’ mechanical performance. The wettability of Ag-Cu-Pd filler metal on niobium, the interface microstructure and mechanical properties of the transition joints were investigated. Two kinds of Ag-Cu-Pd filler metals had been studied and wet well on the niobium, and the wettability of Ag-31.5Cu-10Pd filler metal on niobium was better than Ag-28Cu-20Pd filler metal. Microstructure characterization demonstrated the absence of brittle intermetallic layers in all of the joint interfaces. Mechanical properties of samples prepared with Ag-31.5Cu-10Pd filler metal were also better than their peers made with Ag-28Cu-20Pd filler metal both room temperature (300 K) and liquid nitrogen temperature (77 K). The transition joints displayed shear strengths of 356-375 MPa at 300 K and 440-457 MPa at 77 K, respectively. After undergoing ten thermal cycles between the room temperature and the liquid nitrogen temperature, the transition joints’ leak rates were all lower than 1.1×10 –11 mbar·L/s. Therefore, Ag-Cu-Pd filler metal is applicable to high vacuum vessels used at cryogenic temperatures.
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Authors and Affiliations

Ruoxu Wang
1 2 3
Lubei Liu
1 2
Zongheng Xue
1 2
Teng Tan
1 2

  1. Chinese Academy of Sciences, Institute of Modern Physics, Lanzhou, Gansu 730000, China
  2. The Advanced Energy Science and Technology Guangdong Laboratory, Huizhou, Guangdong 516000, China
  3. Anhui East China Photoelectric Technology Research Institute, Wuhu, Anhui 241002, China
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Abstract

High temperature vacuum brazing is a well-known and commonly used method for joining of nickel based elements and subassemblies of gas turbines, both for stationary and aviation applications. Despite the fact that currently used brazing filler metals meet stringent requirements of aviation and energetic industries, a lot of effort is spent on improving operational properties of the joints through modification of chemical composition or brazing process parameters. This paper aims for both of these aspects – its purpose is evaluation of the impact of filler metal composition, brazing gap width and process conditions on the microstructure of joints between sheet metal elements made of Hastelloy X nickel superalloy. Two different Ni-based filler materials (BNi-2 and Amdry 915) were investigated, based on the results of light and scanning electron microscopy evaluations, energy dispersive X-ray spectroscopy and hardness measurements.
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Authors and Affiliations

K. Krystek
1 2
ORCID: ORCID
K. Krzanowska
1
ORCID: ORCID
M. Wierzbińska
1
ORCID: ORCID
M. Motyka
1
ORCID: ORCID

  1. Rzeszow University of Technology, Department of Materials Science, 12 Powstańców Warszawy Av., 35-959 Rzeszów, Poland
  2. Pratt & Whitney Rzeszów S.A., 120 Hetmańska Str., 35-078 Rzeszów, Poland
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Abstract

The article discusses tests concerning the assessment of the corrosion resistance, properties and the structure of TIG braze welded galvanised steel sheets. Test butt joints were made of 0.9 mm thick galvanised car body steel sheets DC04 (in accordance with EN 10130), using a robotic welding station and a CuSi3Mn1 braze (in accordance with PN-EN 13347:2003) wire having a diameter of 1.0 mm. The research-related tests aimed to optimise braze welding parameters and the width of the brazing gap. The test joints were subjected to visual tests, macro and microscopic metallographic tests, hardness measurements as well as tensile and bend tests. The corrosion resistance of the joints was identified using the galvanostatic method. The tests revealed that it is possible to obtain high quality joints made of galvanised car body steel sheets using the TIG braze welding process, the CuSi3Mn1 braze and a brazing gap, the width of which should be restricted within the range of 0.4 mm to 0.7 mm. In addition, the joints made using the aforesaid parameters are characterised by high mechanical properties. The minimum recommended heat input during process, indispensable for the obtainment of the appropriate spreadability of the weld deposit should be restricted within the range of 50 kJ/mm to 70 kJ/mm. At the same time, the aforesaid heat input ensures the minimum evaporation of zinc. Joints made using the TIG braze welding method are characterised by high resistance to electrochemical corrosion. The galvanostatic tests did not reveal any traces of corrosion in the joint area.

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Authors and Affiliations

J. Górka
ORCID: ORCID
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Abstract

The Controlled Atmosphere Brazing (CAB) process together with NOCOLOKr flux is associated with the occurrence of potassium fluoroaluminate residue inside the cooler. Excess of this flux residue is known to cause gelation of the coolant, which deteriorates the efficiency of the cooler. The flux residue amount is most often measured via Atomic Absorption Spectroscopy (AAS), in accordance with DIN ISO 9964-3. This is a time-consuming measurement that requires the use of specialized equipment and costly solvents. The following article presents two innovative methods for flux residue measurement after CAB process. They include Scanning Electron Microscopy (SEM) with Energy-Dispersive X-ray Spectroscopy (EDS) and Reflected Light Microscopy (RLM) with Differential Interference Contrast (DIC) module. The accuracy of these methods has been compared to the reference AAS method to evaluate their potential as alternative, less expensive, and quicker measurement methods for determining the quantity of flux residue.
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Authors and Affiliations

Sławomir NADOLNY
Adam Hamrol
ORCID: ORCID
Michał Rogalewicz
ORCID: ORCID
Adam Piasecki
ORCID: ORCID
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Abstract

On the basis of research, the mechanisms of dissolution and erosion during brazing of aluminium alloys and the influence of these phenomena on brazed joints of heat exchangers are presented. A number of factors have been identified that affect the formation of these phenomena during brazing aluminium alloys, these include : the maximum temperature and holding time at brazing temperature, and the type and amount of filler metal. The research was supported by examples of dissolution and erosion phenomena during series production of aluminium heat exchangers using three brazing profiles (normal, hot and very hot). It has been found that the dissolution of the engine radiator components during brazing, is from 18 to 68%, depending on the brazing profile used. For a very hot profile, erosion in part of the brazed exchanger, even destroys (removes) thin elements of the cooling fins.
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Bibliography

[1] E . Frąckowiak, W. Mroziński, Using flame brazing technology for producing aluminum automotive heat exchangers, Welding Technology Review 9, 57-62 (2007).
[2] Z. Mirski, K. Granat, A. Misiek, Brazing of aluminum heat exchangers in the automotive industry, Spajanie materiałów konstrukcyjnych 2, 32-34 (2015).
[3] D . Pritchard, Soldering, Brazing, Welding; Crowood Press. (2001).
[4] Z. Mirski, J. Pabian, Modern trends in production of brazed heat exchangers for automotive industry. Welding Technology Review 89 (8), 5-12 (2017).
[5] J. Pilarczyk (Ed.), Engineer’s Guide: Welding, 2, WNT, Warszawa (2014).
[6] K . Ferjutz, J.R. Davis. ASM Handbook 6, Welding, Brazing, and Soldering. 10th ed. ASM International; (1993).
[7] M. Motyka, L. Orman, M. Lech-Grega, M. Nowak, Advanced technics in analysis of quality problems in aluminium brazed heat exchangers, Rudy i Metale Nieżelazne 7 (2010).
[8] J. Nowacki, M. Chudziński, P. Zmitrowicz, Brazing in Mechanical Engineering, WNT, Warszawa (2007).
[9] K . Hyun-Ho, L. Soon-Bok, Effect of a brazing process on mechanical and fatigue behavior of alclad aluminum 3005, Journal of Mechanical Science and Technology 26 (7), 2111-2115 (2012).
[10] A . Sharma, S.H. Lee, H.O. Ban, Y.S. Shin, J.P. Jung, Effect of various factors on the brazed joint properties in Al brazing technology, Journal of Welding and Joining 34 (2), 30-35 (2016).
[11] P.K. Velu, Study of the Effect of Brazing On Mechanical Properties of Aluminum Alloys For Automotive Heat Exchangers; A Thesis Submitted to the Faculty of Purdue University. In Partial Fulfillment of the Requirements for the Degree of Master of Science in Mechanical Engineering Purdue University Indianapolis, Indiana, USA (2017).
[12] M. Nylén, U. Gustavsson, W.B. Hutchinson, A. Örtnäs, Mechanistic Studies of Brazing in Clad Aluminium Alloys, Materials Science Forum 217-222, 1703-1708 (1996).
[13] M. Nylén, U. Gustavsson, W.B. Hutchinson, Å. Karlsson, The Mechanism of Braze Metal Penetration by Migration of Liquid Films of Aluminium Alloys, Materials Science Forum 331-337, 1737-1742 (2000).
[14] T. Yiyou, T. Zhen, J. Jianqing, Effect of Microstructure on Diffusional Solidification of 4343/3005/4343 Multi-Layer Aluminum Brazing Sheet. The Minerals, Metals & Materials Society and ASM International (2012).
[15] M. Nylén, U. Gustavsson, W.B. Hutchinson, Å. Karlsson, H. Johansson, Mechanisms of Erosion during Brazing of Aluminium Alloys, Materials Science Forum 396-402, 1585-1590 (2002).
[16] T. Izumi, T. Ueda, Influence of Erosion Phenomenon on Flow Behavior of Liquid Al-Si Filler Between Brazed Component; 13th International Conference on Aluminum Alloys (ICAA13) Pittsburgh (2012).
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Authors and Affiliations

Z. Mirski
1
ORCID: ORCID
J. Pabian
2
ORCID: ORCID
T. Wojdat
1
ORCID: ORCID

  1. Wroclaw University of Science and Technology, Faculty of Mechanical Engineering, Department of Metal Forming, Welding and Metrology, 27 Wybrzeże Wypiańskiego, 50-370 Wrocław, Poland
  2. Research & Development, MAHLE Behr Ostrów Wielkopolski
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Abstract

Thermal fatigue properties of WCu45/FeCr18Ni9 steel brazed joint with Ni-Cr-Si-B filler metal were investigated. Results indicated that the fatigue damage of Ni-based joint was aggravated with the increased of thermal fatigue cycles times. Moreover, the fatigue cracks appeared in the brazing seam and FeCr18Ni9 steel side near the brazing seam, and the bending strength of the brazed joint decreased from 333 MPa of original joint to 160 MPa of having experienced 200 thermal fatigue cycles. The fracture characteristic of Ni-based joint underwent 200 cycles was identified as mixed ductile-brittle fracture under the combined effect of external bending load and internal fatigue damage.

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Authors and Affiliations

Chunzhi Xia
Linling Fu
Wenchao Du
Xiangping Xu
Xiling Wang
Jiasheng Zou
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Abstract

This paper is focused on investigating the mechanisms associated with different failure modes of copper (C101) sandwich panels with honeycomb cores of different heights subjected to flexural loading. Honeycomb core is made up of copper strips which were formed to required shapes using Dies fabricated by Electric Discharge Wire cut machining technique. All the joints in the sandwich panel were established through Brazing technique. Three-point bending test was conducted as per ASTM standard C-393. It was observed that increase in height of the core resulted in panels with higher strength to weight ratio. It also exhibited higher stiffness to weight ratio and very high strain energy absorption ability. An increase in flexural strength was reported with a maximum of 43% improvement for 10.9 mm core compared to 6.9 mm core. Further, 81.75% increase in absorbed strain energy was reported for 10.9 mm thick panel compared to 6.9 mm. The Optical and scanning electron microscope (SEM) analysis confirmed the establishment of good bonding between the filler and the substrate. Energy-dispersive Spectroscopic (EDS) analysis revealed the presence of Cu, Al, Zn, SiO2 and CaCO3 in the substrate. Further it also revealed the presence of Cu, CaCO3 and GaP in the filler material. The failure mode map was constructed which can be used for predicting different types of failures more likely to occur for specific parameters of copper sandwich panel. The dominant failures occurred during testing was in good agreement with the prediction done through failure mode map. The appreciable results in the proposed research may be supportive in construction of cooling system. The structure development and process control are convenient in mass production in automobile industries.
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Authors and Affiliations

A. Vino
1
ORCID: ORCID
K. Kalaichelvan
1
ORCID: ORCID
S. Sajith
2
ORCID: ORCID
G. Kumaresan
3
ORCID: ORCID

  1. Anna University, Department of Ceramics, AC Techcampus, Chennai, India
  2. Anna University, Department of Aerospace Engineering, MIT Campus, Chennai, India
  3. Bannari Amman Institute of Technology, Department of Mechanical Engineering, Sathya Mangalam, Erode – 638 401, India

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