The Effect of Vanadium and Niobium on the Properties and Microstructure of the Intercritically Reheated Coarse Grained Heat Affected Zone in Low Carbon Microalloyed Steels

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概要

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• Four steels, C–Mn–0.05V, C–Mn–0.11V, C–Mn and C–Mn–0.03Nb, all essentially boron-free were subjected to processing to simulate the microstructure of a coarse grained heat affected zone (GC HAZ) and an intercritically reheated coarse grained HAZ (IC GC HAZ). This involved reheating to 1 350°C, rapid cooling (Δt8/5=24s) to room temperature and then reheating to either 750°C or 800°C. The toughness of the simulated GC HAZ and IC GC HAZ was assessed using both Charpy and CTOD tests and the hardness of both zones was also measured. A detailed assessment of the size and area fraction of martensite–austenite (M-A) phase in the IC GC HAZ in the steels was obtained from a combination of Scanning Electron Microscopy (SEM) and Image Analysis of the resultant SEM micrographs. In addition, the distribution of the M-A phase was examined by observing 250 fields at a magnification of 2 500 times in the SEM for each of the steels.It is clear that the alloying addition has a significant effect on the amount and size of the M-A phase. The addition of 0.05% V to the C-Mn steel resulted in the lowest IC GC HAZ Charpy 50J impact transition temperature and the 0.1 mm CTOD transition temperature. The corresponding size and area fraction of the M-A phase were the smallest of the four steels. Raising the level of vanadium to 0.11% caused a deterioration in IC GC HAZ toughness, which was reflected in a greater area fraction of M-A phase, larger mean and maximum sizes of M-A particles and significantly more fields containing M-A phase. The addition of 0.03%Nb produced poorer IC GC HAZ toughness data than C–Mn–V and C–Mn steels and this was related to the large size and area fraction of M-A phase quantified in the Nb steel. The presence of M-A phase is considered to be the dominant factor in determining the toughness of IC GC HAZ.

• 社団法人 日本鉄鋼協会の論文
• 2001-01-15

著者

• Baker T.

  Metallurgy And Engineering Materials Group Department Of Mechanical Engineering University Of Strath

• Mitchell P

  Vanitec Kent Gbr

• Mitchell P.

  Vanitec

• CROWTHER Y.

  Corus Group, Swinden Technology Center

• GREEN M.

  Corus Group, Swinden Technology Center

• Crowther Y.

  Corus Group Swinden Technology Center

• Green M.

  Corus Group Swinden Technology Center

• Baker T.

  Metallurgy & Engineering Materials Group Department Of Mechanical Engineering Strathclyde Univer

関連論文

• Influence of AIN Precipitation on Thermodynamic Parameters in C-Al-V-N Microalloyed Steels
• The Effects of Vanadium, Niobium, Titanium and Zirconium on the Microstructure and Mechanical Properties of Thin Slab Cast Steels
• The Evolution of Microstructure during Thin Slab Direct Rolling Processing in Vanadium Microalloyed Steels
• The Evolution of Microstructure in Vanadium Microalloyed Steels
• The Effect of Vanadium and Niobium on the Properties and Microstructure of the Intercritically Reheated Coarse Grained Heat Affected Zone in Low Carbon Microalloyed Steels
• The Effect of Welding Process on the Chi Phase Precipitation in As-welded 317L Weld Metals
• Effect of Equalisation Time on the Austenite Grain Size of Simulated Thin Slab Direct Charged (TSDC) Vanadium Microalloyed Steels
• Austenite Grain Growth Behaviour of Microalloyed Al-V-N and Al-V-Ti-N Steels

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