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Title:

Effects of Heat Straightening on the Microstructure and Structural Properties of Bridge Steels

Accession Number:

01045901

Record Type:

Component

Availability:

Transportation Research Board Business Office

500 Fifth Street, NW
Washington, DC 20001 United States

Abstract:

This paper presents an experimental and theoretical investigation of the effects of damage followed by heat straightening repair on the structural properties, fracture toughness, and microstructure of A36, A588, and A7 bridge steels. The damage and repair parameters considered are the damage strain, the restraining stress, and the maximum heating temperature (Tmax). The experimental results and microstructure studies indicate that the heat straightening process repairs not only the inelastic deformations, but also the damage to the steel microstructure. Heat straightening is similar to the heat treatments known as process annealing or normalizing annealing. It induces recovery, recrystallization, and grain growth of the damaged steel microstructure. The extent of recrystallization and grain growth depends on the damage and repair parameters (damage strain, restraining stress, and Tmax). Heat straightening of A36 and A7 steel with Tmax equal to 650 degrees causes partial recovery and recrystallization of the damaged microstructure. Hence, the fracture toughness values are typically lower than the undamaged values. Heat straightening of A588 steel with Tmax equal to 650 degrees causes significant recrystallization, and grain growth of the damaged microstructure. Hence, the grain sizes are larger and the fracture toughness values are comparable or greater than the undamaged values. Heat straightening of A36 steel with Tmax equal to 760 or 870 degrees leads to complete recrystallization of the damaged microstructure. The resulting steel has a finer and more uniform grain structure with higher yield stress and fracture toughness values than the undamaged steel.

Monograph Accession #:

01042056

Report/Paper Numbers:

07-3455

Language:

English

Corporate Authors:

Transportation Research Board

500 Fifth Street, NW
Washington, DC 20001 United States

Authors:

Kowalkowski, Keith Joseph
Varma, Amit Hariom

Pagination:

27p

Publication Date:

2007

Conference:

Transportation Research Board 86th Annual Meeting

Location: Washington DC, United States
Date: 2007-1-21 to 2007-1-25
Sponsors: Transportation Research Board

Media Type:

CD-ROM

Features:

Figures; Photos; References (24) ; Tables (5)

Uncontrolled Terms:

Bridge structures; Heating (Bridge)

Subject Areas:

Bridges and other structures; Design; Highways; I24: Design of Bridges and Retaining Walls

Source Data:

Transportation Research Board Annual Meeting 2007 Paper #07-3455

Files:

TRIS, TRB

Created Date:

Feb 8 2007 8:08PM