ABSTRACT

The phase of steel changes from austenite to martensite, bainite, ferrite, and pearlite whether it is a rapid cooling or a slow cooling in the actual cooling process after line heating in shipyards. In order to simulate the cooling process, heat transfer analysis was performed considering the effects of impinging water jet, film boiling, and radiation. From above simulation it is possible to find the cooling speed at the inherent strain region and volume percentage of all phases in that region. By the suggested method based on the precise material properties calculated from volume percentage of all phases, it will be possible to predict the plate deformations by line heating more precisely. It is verified by comparing with some experimental results that the present method is very effective and efficient.

INTRODUCTION

Hull forming has been done by experts through repeating process in trial and error. So automatic hull forming process is needs to improve ship productivity and it is necessary to predict deformation of hot working precisely. It is possible to predict deformation of hot working precisely when property of hot working part induced precisely. For this, it is required to examine phase transformation in heating line closely. The phase in heating line is transformed in cooling process. Therefore it is required to stimulate heat transfer in cooling process.

Until now, it is just focused on study of heating process in heating line, so it is proved to deformation mechanism in thermal elasto-plastic analysis. But, to predict deformation precisely, it is necessary to consider deformation by phase transformation.

HEAT TRANSFER ANALYSIS IN COOLING PROCESS OF LINE HEATING

Heat transfer is performed by conduction, convection, and radiation. But heat transfer in cooling process of plate surface is usually achieved by convection and radiation.

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