The Development of High Strength Steel Plate with Improved Toughness and Weldability for Steel Box Girder of Elevated Highway Application

Transcription

1 The Development of High Strength Steel Plate with Improved Toughness and Weldability for Steel Box Girder of Elevated Highway Application Zaenal A. Muslim, Anang Sya roni, Syahriar Fakhrurrozi 2017

2 Introduction In the recent years, infrastructure development in Indonesia continues to be intensively undertaken by the Government, such as toll roads, bridges, ports, railways, airstrips and others. Infrastructure projects currently being worked is an elevated toll road project using a welded steel box girder.

3 Project Location of Jakarta Cikampek II Elevated Highway JAKARTA CIKAMPEK JAKARTA CIKAMPEK II ELEVATED HIGHWAY Sta s/d ( 36,8 KM ) 3

4 Introduction Steel welded joint structures are selected with some consideration, such as: faster in fabrication and assembling, high quality cost but optimally distributed for the large number of spans, as well as better in term of aesthetic. Steel for this application requires not only high strength and toughness but also good weldability.

5 Product Specification The steel type was in accordance to JIS G 3106 SM520B and several technical document of the projects. To ensure that mass production will not be impaired using this type of steel, special production trials were performed before final selection of the steel type. Tests of steel plates were performed through the girder manufacturer before commencement of production. Chemical Composition. Grade C Mn Si P S Al N Nb Cu+Ni+Cr CE (IIW) CE (PCM) SM520B Typical Spec. max

6 Steel Making Steel making process route. The steel making and casting practices can be summarized as follows: Dephosporization process during primary melting and slag free tapping for maximum achievement of steel cleanliness; Hot metal desulphurization and calcium treatment by injecting CaSi wire; Casting into tundish with weirs, argon gas purging and extended shroud to float up non metallic inclusion and to minimize re-oxidation during casting. Controlling superheat and casting speed

7 Hot Rolling Flow of main process at HSM to produce hot rolled coil and plate is shown in Figure. Brief description of hot rolling process is as follows: The slabs are reheated in the reheating furnace to reach temperature at about C; The slabs are rolled in the roughing mill in producing transfer bars. Final working pass reduction in the roughing stage is about 15-20% at the recrystallization region; The transfer bars are rolled in the finishing mill to become strips. The total aim finishing reduction is approximately 70% below the no-recrystallization temperature, and the exit temperature at the last active stand is C; On the way to down coiler, the strips are cooled in the laminar cooling. The target cooling rate and coiling temperature were ~10 C/s and 650 C. The process of cutting coil into plate is conducted in shearing line #1 equipped with leveler to improve plate flatness.

8 Results The results of tensile test data are presented in table. Data show steel plate meets all requirements according to the standards set forth in the project. Figure shows the Charpy Impact Test results at -40, -20, 0, and 20 C. The result of Charpy test indicates that the material has a very good toughness even at very low temperature. Standard Actual (t = 22.2 mm) YS (MPa) 355, min UTS (MPa) Elongation (%) 19, min Charpy at O C (J) 27, min MECHANICAL PROPERTIES Joule C Charpy Impact Test Results

9 Results The metallographic observation which are undertaken on samples at the surface and quarter thickness of steel, as shown in Figure below, mostly comprises fine ferrite of 5-30 µm grain size and fine lamellar pearlite with its condition tended to become disperse evenly. The steel contains a medium amount of carbon and a heavy strip thickness so that the reduction force in the middle of the strip thickness is not sufficient to disperse the pearlite. However, the pearlite condition is not severe and does not affect the strength and toughness of steel. Microstructure at Surface Microstructure at Quarter Microstructure at Middle

10 THE MANUFACTURING PROCESS OF WELDED JOINT BOX GIRDER Prior to fabrication phase, a series of tests were performed. The test includes welding test, coating test, and mock-up. All of welding processes in this box girder manufacturing will be developing using AWS D Bridge welding code standard, and will be written in welding procedure specification (WPS). The tests described in next slide table are used to determine the mechanical properties and the soundness of material that affected by welding process. The results is that the steel plate fulfills the requirements of high strength welded joint girder for elevated highway project.

11 THE MANUFACTURING PROCESS OF WELDED JOINT BOX GIRDER As the result of mechanical testing of samples for WPS development shows that the material SM520B are met the designation for welding process code AWS D No. Weld Grade Reduce Section Tension Charpy V-Notch Impact Material Test PQR No. Process & Position Base Metal T1 (MPa) T2 (MPa) T avg (MPa) Break Location Type of Fracture Fusion C (Joule) Fusion Line C (Joule) CVN 12 C (Joule) F001 FCAW/3G SM520B Base Metal Ductile F002 FCAW/1G SM520B Base Metal Ductile F003 FCAW/3G SM520B Base Metal Ductile F004 FCAW/1G SM520B Base Metal Ductile F008 FCAW/3G SM520B Base Metal Ductile F008 FCAW/1G SM520B Base Metal Ductile F012 FCAW/3G SM520B Base Metal Ductile F013 FCAW/1G SM520B Base Metal Ductile S001 SAW/1G SM520B Base Metal Ductile S005 SAW/1G SM520B Base Metal Ductile S009 SAW/1G SM520B Base Metal Ductile

12 THE MANUFACTURING PROCESS OF WELDED JOINT BOX GIRDER The main fabrication process of steel box girder consists of cutting, welding and assembling. Fabrication process involves many stages of workmanship from incoming material inspection, the determination of proper welding procedures and perfect welding details, hot dip galvanizing and painting, quality control over the work, and the selection of equipment with the proper technology.

13 THE MANUFACTURING PROCESS OF WELDED JOINT BOX GIRDER

14 Thanks