Dissertation > Excellent graduate degree dissertation topics show

Research on Technology and Mechanism of Joining Cemented Carbide to Carbon Steel

Author: YueZuo
Tutor: FengJiCai
School: Harbin Institute of Technology
Course: Materials Processing Engineering
Keywords: cemented carbide compound roller Cu intermediate layer microstructure MARC numerical simulation
CLC: TG454
Type: Master's thesis
Year: 2008
Downloads: 136
Quote: 0
Read: Download Dissertation

Abstract


In order to meet the urgent requirement of high-quality compound roller in iron and steel industry, vacuum brazing of cemented carbide to carbon steel was carried out using Ni-based brazing alloy with and without Cu intermediate layer. The influence of brazing temperature over microstructure and mechanical property of the vacuum brazed joints was analyzed, and the mechanism of the formation of interfacial microstructure was investigated. The MARC software was applied to study the postweld residual stress field of the compound rollers, which were brazed with and without Cu intermediate layer.The interfacial reactions of the WC-Co/Steel joints brazed using Ni-based brazing alloy were discussed experimentally and theoretically. The results showed that microstructure of the joint was Steel/Fe-Ni(s.s)/γ-Ni(s.s)/ W-Co-Ni rich /WC-Co when brazing temperature was 1040℃. In addition, the width of the interfacial reaction layers changed obviously with the variation of the brazing temperature, and the reaction layers, especially W-Co-Ni rich, exerted a great influence over the mechanical property of the brazed joints. The maximum shear stress was 340MPa, which was achieved when the brazing temperature was 1040℃, and fractures occurred at WC-Co cemented carbide.In order to reduce the postweld residual stress of the compound roller, a novel technology of brazing using Ni-based brazing alloy with Cu intermediate layer was put forward. The results showed that the shear stress of the brazed joints increased with the increment of the brazing temperature when the thickness of Cu was 250um. When brazing temperature was 1070℃, microstructure of the joint was Steel/Fe-Ni(s.s)/Cu/Ni-Co(s.s)/WC-Co, and the shear stress reached 272MPa. Fractures occurred along the Cu/WC-Co interface. When the thickness of Cu was 100um, the shear stress decreased to 211MPa.The residual stress distribution of compound rollers brazed at the two different conditions was investigated by numerical simulation. The results showed that the cooling speed had a great influence over the postweld residual stress. Taking all the factors into consideration, the optimum value of cooling speed was 30℃/min. Under such cooling speed, the maximum residual stress of roller brazed using Ni-based brazing alloy was 434MPa. However, it decreased dramatically to 69MPa when the optimum Cu intermediate layer of 250um was applied. The results proved that the novel brazing technology with Cu intermediate layer could reduce postweld residual stress successfully.

Related Dissertations

  1. Reactive Hot-Pressing and Mechanical Properties of (ZrB2-ZrO2)/BN Composites,TB332
  2. Microstructure and Mechanical Properties of Mg-Zn-Y-Zr Alloys,TG146.22
  3. Investigation on Microstructure and Properties of Cadmium-Free Silver-Based Intermediate Temperature Filler Metals,TG425.2
  4. The Investigations on the Characteristics and Mechanism of NIR Emission from Bi-doped Silicophosphate Glasses,TQ171.1
  5. Preliminary Study on Salt-Tolerant Mechanism of the New Pennisetum Purpereum Schumach Variety-Sumu No.2,S543.9
  6. Study on the Fine Structure of Intestine and Intestinal Mucosal Barrier in Zebrfish (Brachydanio Rerio),Q95-33
  7. Study on Characteristics of Morphology Anatomy and Physio-Biochemistry of Two Ecotype Varieties Cucumber Leggy Seedilings,S642.2
  8. Study on the Mechanism of Heat-Induced Gelation of Myofibrillar Proteins,TS251.1
  9. Studies on the Aggregation and Microstructure of Imidazolium Ionic Liquids in Solutions,O645.1
  10. Studies of Luminescence Characteristics of Eu3+-doped Rare Earth Borates REBaB9O16 (RE=rare Earth Ions and Y),O627.3
  11. The Research on Extrusion Parameters Through the Plate Billet of Magnesium Alloy,TG379
  12. Study on Stock Price Behavior Around Periodical Reports Based on Asymmetric Information,F832.51
  13. Research on Processings and Microstructure and Properties of HRB400MPa,TG335
  14. Study of Performance of Cordierite Combined Mullite Products,TQ175.71
  15. Effect of Adding ZrO 2 Nanopowder on Microstructure and Mechanical Properties of Carbon Steel,TB383.1
  16. The Broussonetia papyrifera fiber structure and properties of microwave - assisted the degumming process parameters optimization,TS123
  17. Studies on the Influence of Rare Earth Ce on Microstructure and Properties of Huge Heat Input SAW Seam Metal,TG445
  18. Hexagonal boron nitride micro- structure and adsorption properties of,TB383.3
  19. Rolled Mg-Zn-Ce-Zr (Mn) alloy microstructure and mechanical properties of,TG339
  20. Simulated lunar ambient temperature magnesium alloy microstructure and mechanical properties of,TG146.22

CLC: > Industrial Technology > Metallurgy and Metal Craft > Welding, metal cutting and metal bonding > Welding process > Brazing
© 2012 www.DissertationTopic.Net  Mobile