Softening and Flow Stress Behaviour of Nb Microalloyed Steels during Hot Rolling Simulation

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概要

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• The roles of softening and precipitation were investigated by means of hot torsion experiments under conditions simulating either plate or sheet rolling. Six microalloyed steels containing Nb were studied. During the first few finishing passes in the sheet rolling simulations, the mean flow stress (MFS) increased as the interpass time was decreased. Due to strain accumulation, the rate of static recrystallization (SRX) increased significantly after each pass. By taking both strain accumulation and grain refinement into account, it is shown that SRX plays a marked role under sheet rolling conditions, even at temperatures below the no-recrystallization temperature for plate rolling conditions. The accumulated or retained strain reaches the critical value required to initiate dynamic recrystallization only at the lowest entry and rolling temperatures and shortest interpass times. The kinetics of the strain-induced precipitation of NbCN under continuous cooling conditions, taking partial SRX into account, indicate that precipitation begins after 2 to 5 passes when 3 s interpass times are employed, thus reducing further softening. But when 1 s interpass times are used, most of the passes take place before copious precipitation, so that static and post-dynamic (<I>i.e</I>. metadynamic) softening may continue to take place. As a result, the MFS level decreases as the interpass time is shortened during the final passes. The extent of grain refinement was similar in both the sheet rolling and plate rolling simulations. The ferrite grain size is shown to depend on MFS of the final pass, and is independent of the chemical composition of the microalloyed steel.

• 社団法人 日本鉄鋼協会の論文
• 1995-12-15

著者

• Jonas John

  Department of Metals and Materials Engineering, McGill University

• Karjalainen L.

  Department Of Mechanical Engineering University Of Oulu

• Maccagno Terrence

  Department Of Metallurgical Engineering Mcgill University

• Jonas John

  Department Of Materials Engineering Mcgill University

関連論文

• The Ferrite Transformation in Hot Deformed 0.036% Nb Austenite at Temperatures Above the Ae3
• The Dynamic, Static and Metadynamic Recrystallization of a Nb-microalloyed Steel
• Effect of Chromium, Boron and Manganese Additions on the Deformation and Recrystallization Textures of Warm Rolled Low Carbon Steels
• The Deformation Microstructure and Recrystallization Behavior of Warm Rolled Steels
• Effect of alloying elements on the microstructure and texture of warm rolled steels
• Correlation between the Deformation and Post-deformation Softening Behaviours in Hot Worked Austenite
• Effect of Processing Schedule on the Microstructure and Texture of 0.78wt% Cr Extra-low-carbon Steel
• The Formation of Deformatio Induced Ferrite during Mechanical Testing
• Predicting the Critical Stress for Initiation of Dynamic Recrystallization
• Softening and Flow Stress Behaviour of Nb Microalloyed Steels during Hot Rolling Simulation
• Effect of Microstructure on the Cold Headability of a Medium Carbon Steel
• The Ferrite Transformation in Hot Deformed 0.036% Nb Austenite at Temperatures Above the Ae_3
• AIN Precipitation in Dual-phase 3% Si Electrical Steels
• The Hot Strip Mill as an Experimental Tool
• Effect of Finishing Temperature on Hot Band Textures in an IF Steel
• Effect of Silicon on the Kinetics of Nb(C, N)Precipitation during the Hot Working of Nb-bearing Steels
• Characteristics of Static and Metadynamic Recrystallization and Strain Accumulation in Hot-deformed Austenite as Revealed by the Stress Relaxation Method
• Dynamic Transformation of a Low Carbon Steel at Temperatures above the Ae_3
• The Critical Strain for Dynamic Transformation in Hot Deformed Austenite
• Dynamic Transformation Behavior of a Deformed High Carbon Steel at Temperatures Above the Ae3
• The Critical Strain for Dynamic Transformation in Hot Deformed Austenite

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