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Study of the Effect of Molybdenum on Wear Properties and Mechanical Properties of Claded Manganese Steel Created with the Cored Wired Filler Metal

Nasajpour Esfahani, Ali | 2014

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 45512 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science & Engineering
  6. Advisor(s): Kokabi, Amir Hossein; Davami, Parviz
  7. Abstract:
  8. Hadfield’s manganese steel, nominally Fe–1.2%C–13%Mn, is an alloy with inherent toughness, work-hardening characteristics and excellent resistance to some types of adhesive and abrasive wear. However, due to its low yield strength, it may be deformed markedly before its work-hardening become effective. There have been many studies on increasing strenght by alloying manganese steel, but the effects some other alloying additions such as 1 to 2 percent Al, Cr, W, V despite increase strenght and wear resistance at the low stress abrasive condition, decrease work-hardening characteristics and wear resistance at the high stress abrasive condition. The aim of present work, is to modify Hadfield’s steel by molybdenum addition to evaluate the increment of the strength, abrasive wear resistance, metal-on-metal wear resistance and change in work-hardening, quantitatively. A cored wired Filler metal with an appropriate combination can be used for cladding a low carbon steel substrate to withstand in hard abrasive wear conditions associated with severe impacts in the mineral processing industry and metal-on-metal friction conditions.
    For this, five types of cored wired filler metal contained 0%Mo, 0.7%Mo, 1.2%Mo, 1.7%Mo, 2.2%Mo and the same percentage of C, Mn, Si were manufactured. They were cladded on the surface of the St40 steel by GTAW welding process. The samples were seprated into two groups. Group one was kept just as-weld but a thermal solutional annealing followed by water quenching was applied to another group (to achieve a non-carbide micro-structure). The hardness, abrasive wear, metal-on-metal wear (Pin on disc), charpy impact strength at ambient temperature and tensile tests were examined for both as-weld and heat-treated samples. The microstructures were studied by optical microscopy and scanning electron microscopy (SEM) for evaluation of carbides volume percentage and type, the fracture surface and the metal-on-metal friction surfaces as well. To determine the phases types formed by welding process, the sample were examined by X-ray spectroscopy. The formation of molybdenum carbide and combined carbide of iron and manganese was carried out. Also, two samples were collected and each one work hardened in a different precedure. One was hammered and the other surface rolled. The effect of Primary work hardening on the increment of the metal on metal wear resistance was investigated.
    The results indicated an increase in the yield strength, ultimate tensile strength, ductility, hardness and wear resistance with increasing molybdenum in the claded Hadfield steel with no reduction in work-hardening characteristics in both as-weld and heat treated samples.
  9. Keywords:
  10. Abrasive Wear ; Work Hardening ; Austenitic Manganes Steel ; Cored Wired Filler Metal

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