• Title/Summary/Keyword: brazing joint

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A Study on the Strength of Brazed Joint for Automotive EGR Cooler by Heat Treatment Conditions (열처리조건에 의한 자동차용 EGR쿨러의 브레이징부 접합강도에 관한 연구)

  • Lee, Joon;Han, Chang-Suk
    • Journal of the Korean Society for Heat Treatment
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    • v.22 no.4
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    • pp.210-216
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    • 2009
  • Stainless steel EGR cooler of diesel engine is widely used to prevent the corrosion due to the content of sulfur in diesel fuel. The strength of brazed joint between stainless steel materials is very important. It is essential to observe the spreading ratio of the filler metals under the condition of deoxidation or vacuum during heating process. In this experiment, spreading ratio was tested to find the optimum brazing condition for stainless steel using brazing filler metals of FP-613, BNi-2 and BNi-5 on sus304 and sus410. Anti-corrosion tests were also performed on the above filler metals with solution of 5% $H_2SO_4$, 65% $HNO_3$ and 5% $NH_4OH$. Consequently FP-613 has good ability for anti-corrosion with 30% of chromium content compared with other filler metals. The optimum brazing conditions are occurred at $960^{\circ}C$ for 90 min. and at $1090^{\circ}C$ for 50 min. at the same degree of vacuum, $2{\sim}3{\times}10^{-3}$ Torr.

Effects of Reactive Air Brazing Parameters on the Interfacial Microstructure and Shear Strength of GDC-LSM/Crofer 22 APU Joints

  • Raju, Kati;Kim, Seyoung;Seong, Young-Hoon;Yoon, Dang-Hyok
    • Journal of the Korean Ceramic Society
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    • v.56 no.4
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    • pp.394-398
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    • 2019
  • In this paper, the joining characteristics of GDC-LSM ceramics with Crofer 22 APU metal alloys was investigated at different brazing temperatures and holding times by reactive air brazing. Brazing was performed using Ag-10 wt% CuO filler, at three different temperatures (1000, 1050, and 1100℃ for 30 minutes) as well as for three different holding times (10, 30, and 60 minutes at 1050℃). The interfacial microstructures were examined by scanning electron microscopy and the joining strengths were assessed by measuring shear strengths at room temperature. The results show that with increasing brazing temperature and holding time, joint microstructure changed obviously and shear strength was decreased. Shear strength varied from a maximum of 100±6 MPa to a minimum of 18±5 MPa, depending on the brazing conditions. These changes were attributed to an increase in the thickness of the oxide layer at the filler/metal alloy interface.

Low Temperature Diffusion Brazing of Commercial Pure(CP)-Ti alloy with Zr-based Filler Metal (Zr기 필러메탈을 이용한 상용 순 티타늄(CP-Ti) 합금의 저온 브레이징 특성)

  • Sun, J.H.;Shin, S.Y.;Hong, J.W.
    • Journal of the Korean Society for Heat Treatment
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    • v.29 no.1
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    • pp.1-7
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    • 2016
  • Titanium and its alloys can be usually joined with brazing method. And the alloys should be brazed at low temperature to keep their original microstructure. In this study, the mechanical strength and microstructure of the CP-Ti joint-brazed with $Zr_{54}Ti_{22}Ni_{16}Cu_8$ filler metal having melting temperature of $774{\sim}783^{\circ}C$ were investigated. The tensile strengths of the joint-brazed at $800^{\circ}C$ with $100^{\circ}C/min$ of cooling rate showed more than 400 MPa which was as high as base metal. The $Widmanst{\ddot{a}}tten$ structure consisting of Ti and $Ti_2Ni$ phase was observed in the joint area. However, the tensile strengths of the joint-brazed at $800^{\circ}C$ with $15^{\circ}C/min$ of cooling rate were decreased and the Ti, $(Ti,Zr)_2Ni$ and $Ti_2Ni$ phases were observed at the joint area. It is believed that the $(Ti,Zr)_2Ni$ laves phases could decrease the mechanical strength of the joint and the cooling rate should be controled to get high strength of the titanium joint.

Effect of Interlayers on the Bending Strength of Silicon Nitride/Staineless Steel Joints (중간재가 질화규소/스테인레스 스틸 접합체의 굽힘강도에 미치는 영향)

  • 박상환;최영화;김태우
    • Journal of the Korean Ceramic Society
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    • v.33 no.3
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    • pp.251-258
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    • 1996
  • The reactions between an active metal brazing alloy and interlayers together with the effects of interlayer type on the interfacial microstructure change were investiaged for silicon nitride/stainless steel joint. The bending strengths were measured for joints with Mo, Cu, Ni interlayer type of different thicknesses. It was found that the interlayer with a low yield strength value is effective to improve the bending strength of the Si3N4/stainless steel joint. The maximum joint strength obtained at room temperature for a laminated Cu/Mo interlayer was about 460 MPa. The combined use of Mo and thin Cu layer was found to be effective in enhancing the bending strength for the Si3N4/S.S.316 joint.

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Optimization of arc brazing process parameters for exhaust system parts using box-behnken design of experiment

  • Kim, Yong;Park, Pyeong-Won;Park, Ki-Young;Ryu, Jin-Chul
    • Journal of Welding and Joining
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    • v.33 no.2
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    • pp.23-31
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    • 2015
  • Stainless steel is used in automobile muffler and exhaust systems. However, in comparison with other steels it has a high thermal expansion rate and low thermal conductivity, and undergoes excessive thermal deformation after welding. To address this problem, we evaluated the use of arc brazing in place of welding for the processing of an exhaust system, and investigated the parameters that affect the joint characteristics. Muffler parts STS439 and hot-dipped Al coated steel were used as test specimens, and CuAl brazing wire was used as the filler metal for the cold metal transfer (CMT) welding machine, which is a low heat input arc welder. In addition, a Box-Behnken design of experiment was used, which is a response surface methodology. The main process parameters (current, speed, and torch angle) were used to determine the appropriate welding quality and the mechanical properties of the brazing part was evaluated at the optimal welding condition. The optimal processing condition for arc brazing was 135A current, 51cm/min speed and $74^{\circ}$ torch angle. The process was applied to an actual exhaust system muffler and the prototype was validated by thermal fatigue, thermal shock, and endurance limit tests.

Preliminary Investigation on Joining Performance of Intermediate Heat Exchanger Candidate Materials of Very High Temperature Reactor(VHTR) by Vacuum Brazing (진공 브레이징을 이용한 고온가스냉각로 중간 열교환기 후보재료의 접합성능에 관한 예비시험)

  • Kim, Gyeong-Ho;Kim, Gwang-Ho;Lee, Min-Gu;Kim, Heung-Hoe;Kim, Seong-Uk;Kim, Suk-Hwan
    • Proceedings of the KWS Conference
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    • 2005.11a
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    • pp.195-197
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    • 2005
  • An intermediate heat exchanger(IHX) is a key component in a next-generation VHTR with process heat applications such as hydrogen production and also for an indirect gas turbine system. Therefore, high temperature brazing with nickel-based filler metal(MBF-15) was carried out to study the joining characteristic(microstucture, joining strength) of nickel-based superalloy(Haynes 230) by vacuum brazing. The experimental brazing was carried out at the brazing process, an applied pressure of about 0.74Mpa and the three kinds of brazing temperatures were 1100, 1150, and $1190^{\circ}C$ with holding time 5 minute. It's joining phenomena were analyzed by optical microscopy and scanning electron microscopy with EPMA. The results of microstructure in the centre-line region of a joint brazed with MBF-15 show a typical ternary eutectic of v-nickel, nickel boride and chromium boride.

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Alloy Design and Powder Manufacturing of Al-Cu-Si alloy for Low-Temperature Aluminum Brazing (저온 알루미늄 브레이징용 Al-Cu-Si-Sn 합금 설계 및 분말 제조)

  • Heeyeon Kim;Chun Woong Park;Won Hee Lee;Young Do Kim
    • Journal of Powder Materials
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    • v.30 no.4
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    • pp.339-345
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    • 2023
  • This study investigates the melting point and brazing properties of the aluminum (Al)-copper (Cu)-silicon (Si)-tin (Sn) alloy fabricated for low-temperature brazing based on the alloy design. Specifically, the Al-20Cu-10Si-Sn alloy is examined and confirmed to possess a melting point of approximately 520℃. Analysis of the melting point of the alloy based on composition reveals that the melting temperature tends to decrease with increasing Cu and Si content, along with a corresponding decrease as the Sn content rises. This study verifies that the Al-20Cu-10Si-5Sn alloy exhibits high liquidity and favorable mechanical properties for brazing through the joint gap filling test and Vickers hardness measurements. Additionally, a powder fabricated using the Al-20Cu-10Si-5Sn alloy demonstrates a melting point of around 515℃ following melting point analysis. Consequently, it is deemed highly suitable for use as a low-temperature Al brazing material.

Type Classification and Shape Display of Brazing Defect in Heat Exchanger (열교환기 브레이징 결함의 유형 분류 및 형상 디스플레이)

  • Kim, Jin-Young
    • Journal of Institute of Control, Robotics and Systems
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    • v.19 no.2
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    • pp.171-176
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    • 2013
  • X-ray cross-sectional image-based inspection technique is one of the most useful methods to inspect the brazing joints of heat exchanger. Through X-ray cross-sectional image acquisition, image processing, and defect inspection, the defects of brazing joints can be detected. This paper presents a method to judge the type of detected defects automatically, and to display them three-dimensionally. The defect type is classified as unconnected defect, void, and so on, based on location, size, and shape information of defect. Three-dimensional display which is realized using OpenGL (Open Graphics Library) will be helpful to understand the overall situation including location, size, shape of the defects in a test object.

Development of Flux for Aluminium Brazing (알루미늄 경납땜용 용제의 개발)

  • 강성개;이봉원;이철구
    • Journal of Welding and Joining
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    • v.11 no.2
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    • pp.13-20
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    • 1993
  • The object of the research is to develop the flux for aluminum brazing. Five kinds of flux were applied to brazing joint with fin and tube structure using same filler metal. To estimate the performance of the developed flux, products analysis, differential thermal test, grain size test, observation of crystalline structure, tensile test, corrosion test were made. From the results of experiment, the following conculsions were obtained. 1. The optimum composition ratio (Wt) of AlF$_3$ and KF was 50-60% : 40-50% 2. The optimum melting point of the flux was 567-578$^{\circ}C$.

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A Study on SiC/SiC and SiC/Mild steel brazing by the Ag-Ti based alloys (Ag-Ti계 합금을 사용한 SiC/SiC 및 SiC/연강 브레이징에 대한 연구)

  • 이형근;이재영
    • Journal of Welding and Joining
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    • v.14 no.4
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    • pp.99-108
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    • 1996
  • The microstructure and bond strength are examined on the SiC/SiC and SiC/mild steel joints brazed by the Ag-Ti based alloys with different Ti contents. In the SiC/SiC brazed joints, the thickness of the reaction layers at the bond interface and the Ti particles in the brazing alloy matrices increase with Ti contents. When Ti is added up to 9 at% in the brazing alloy. $Ti_3SiC_2$ phase in addition to TiC and $Ti_5Si_3$ phase is newly created at the bond interface and TiAg phase is produced from peritectic reaction in the brazing alloy matrix. In the SiC/mild steel joints brazed with different Ti contents, the microstructure at the bond interface and in the brazing alloy matrix near SiC varies similarly to the case of SiC/SiC brazed joints. But, in the brazing alloy matrix near the mild steel, Fe-Ti intermetallic compounds are produced and increased with Ti contents. The bond strengths of the SiC/SiC and SiC/mild steel brazed joints are independent on Ti contents in the brazing alloy. There are no large differences of the bond strength between SiC/SiC and SiC/mild steel brazed joints. In the SiC/mild steel brazed joints, Fe dissolved from the mild steel does not affect on the bond strength of the joints. Thermal contraction of the mild steel has nearly no effects on the bond strength due to the wide brazing gap of specimens used in the four-point bend test. The brazed joints has the average bond strength of about 200 MPa independently on Ti contents, Fe dissolution and joint type. Fracture in four-point bend test initiates at the interface between SiC and TiC reaction layer and propagates through SiC bulk. The adhesive strength between SiC and TiC reaction layer seems to mainly control the bond strength of the brazed joints.

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