Dissertation > Excellent graduate degree dissertation topics show

Research on Hot Deformation Behaviors and Phase Transformation Kinetics of Nb-Microalloyed Ship Plate Steels

Author: WeiJiang
Tutor: XiaoFuRen
School: Yanshan University
Course: Materials Science
Keywords: high content Nb ship plate steel austenite grain hot deformation recrystallization activation energy statically soft strain-induced precipitation continuous cooling phase transition
CLC: TG142.15
Type: Master's thesis
Year: 2010
Downloads: 162
Quote: 0
Read: Download Dissertation

Abstract


In this thesis, the hot deformation behaviors and phase transformation kinetics of two ship plate steels with different compositions were studied. The purpose was to explore the feasibility for acceding to high content Nb in ship plate micro-alloying process.Solid solution process and austenite grain growth of high-Nb ship plate steels were discussed by reheat treatment process and chemical analysis technology, confirmed the temperature of anstenization. Dynamic recrystallization, static recrystallization behavior and strain-induced precipitation were studied in Gleeble-3500 thermo mechanical simulator, thus, the influences of acceding to high content Nb on the hot deformation behaviors were analyzed, furthermore, in the processes of continuous cooling transformation of high-Nb ship plate steels, the phase transformation kinetics and the microstructure were researched, the influences of deformation processes and high content Nb on the phase transformation were analyzed.The results showed that the temperature at 1100℃was grain coarsening temperature in the process of austenite grain growth, under this temperature, the growth of austenite grain size was in a low speed, the size of two steels austenite grain had small discrepancy, while austenite grain growth of two steels increased with a high speed over coarsening temperature.In hot deformation processes, it was found that steel B have more higher activation energy than steel A by calculating. It was found that steel B have a more longer gestation period than that in steel A by analyzing statically soft fraction, so the difficulty level of the recrystallization in steel B was greater than that in steel A. Precipitation-start time of steel B was shortened while precipitation temperature was lower than those of steel A by analyzing the stain induced carbide precipitation curves (PTT curves). Under-cooled austenite continuous cooling phase transition kinetics and the microstructure of steels were analyzed, the results showed that grain size reduced and the beginning point of phase transformation for acicular ferrite raised notablely. The influence of high content Nb addition on the phase transformation mainly manifested as, austenite had good thermal stability and the ferrite phase transformation point decreased by the function of the solid solution drag force, while grain size reduced observably because strain-induced precipitation of Nb increased nucleation rate.

Related Dissertations

  1. Research on Effects of Hot Deformation Behaviore of Pipeline Steels for High Pressure Gas Transportaion,TG142.15
  2. Study on Subsequent Processing and Microstructure and Properties of Spray Deposited GCr15 Bearing Steel,TG335
  3. Investigation on Hot Deformation Behavior of Ferritic Stainless Steel,TG142.71
  4. The Hot Deformation Behavior and Hot Processing Map of Cr-Mn-Ni-Cu-N Austenitic Stainless Steel,TG142.71
  5. Numerical Simulation of the DC Flash Butt Welding for Ultra-Fine Grain Size Steel and Prediction of Microstructure and Property,TG407
  6. Study on the Weldability of High Strength Bridge Steel,TG457.11
  7. A Study on Fabrication, Heat-Treatments and Mechanical Properties of V-Nb Microalloyed Gear Steel,TG142.12
  8. The Research of the Model to Predict the Grain Growth in Steel Reheating Process,TG335.11
  9. Study of Grain Refinement of CFB/M Steel,TG142.2
  10. Investigation of Temperature Field Simulation and Transformation Behavior during Continuous Cooling on Hot Rolling Hull Plate,TG335
  11. Austenitic stainless steels and high temperature oxidation behavior of grain growth,TG142.71
  12. Influence of Cleanliness on Mechanical Properties of 38CrMoAlA Nitriding Steel,TG156.82
  13. Study of Grain Refinement, Hot Deformation Behavior and Working Technology of Mg-Al Alloys,TG301
  14. Microstructural Evolution and Process Optimization of Q345E Steel During Heating and Rolling,TG335
  15. A new Al-Mg-Si-Cu alloy hot extrusion deformation behavior and Heat Treatment,TG156
  16. Rare Earth Elements on ZK60 alloy and thermal deformation behavior of,TG113
  17. Mg-Gd-Y-Zr Magnesium Alloys , Performance,TG146.22
  18. Study on the Hot Extrusion and Microtructure Evolution of AZ80 Magnesium Alloy Tubes,TG376
  19. Design and Study of Ic Engine Piston Skirt Profile Based on Fem,TK403
  20. Investigation on Texture and Microstructure Evolution of Ultra-high Purity Al-0.5%Cu Alloy During Rolling and Annealing,TG166.3

CLC: > Industrial Technology > Metallurgy and Metal Craft > Metallurgy and Heat Treatment > Metallic materials > Steel > Microstructure and properties of steel > Analysis of the steel test
© 2012 www.DissertationTopic.Net  Mobile