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Title

REDUCING THE WARPING EFFECT ON HOT ROLLED STEEL SAE 15B29 FLAT BARS

Authorship

Gazola, Pedro Emílio; Lima, Mariana Macedo de Oliveira; Locatelli, Andrei; Daroit, Mateus

Gazola, Pedro Emílio

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Lima, Mariana Macedo de Oliveira

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Locatelli, Andrei

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Daroit, Mateus

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DOI

10.5151/9785-9785-32240

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Abstract

Boron steel is used in the industry due to its great wear and impact resistance. During the hot rolling production of 15B29 steel flat bars it is a recurrent problem that the bars will present warping while on the cooling bed. Control this phenomenon is an opportunity to have better productivity, preventing metallic losses. Through the observation of the macro and microstructure samples produced with different reheating temperatures and cooling rates, it was found the presence of residual stresses and cracks on warped bars macrostructure. The residual stresses appearance suggest that the material cooling is too fast. Billets temperature on the reheating furnace of 1230°C reduced to 1100°C and the production pace slowed down. Bars temperature when arriving the cooling bed was reduced from higher than 670°C to 625°C. The results obtained made it possible to produce the material with better quality, reducing the warping effect at the cooling bed. The major influence on the materials warping was identified as the cooling rate at the cooling bed and the reheating furnace temperature was adjusted to provide a homogeneous temperature along the bars.

Keywords

SAE 15B29; Warping; Flat bars; Cooling Rate; Residual Stresses; Hot Rolling;boron.