Title

MANDREL BAR'S RECOVERY OF PROPERTIES BY QUENCHING AND TEMPERING PROCESS

MANDREL BAR'S RECOVERY OF PROPERTIES BY QUENCHING AND TEMPERING PROCESS

Authorship

Diniz, Ivan César Lopes; Júnior, César Romero Afonso Goulart

Diniz, Ivan César Lopes

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Júnior, César Romero Afonso Goulart

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DOI

10.5151/2594-5297-32371

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Abstract

mandrel mill is a process used to manufacture seamless tubes. the process consists in 8 stands using 2 rolls in each stand reducing the outside diameter and one mandrel inside of the shell to keep the inside diameter. THE WALL THICKNESS of the tube IS the main result of this process. the pqf (premium quality finishing) has the same objective concerning wall thickness, but with high quality. vallourec has, in partnership with sumitomo, a pqf located at jeceaba. the mandrel from this process has the same material specification. an opportunity was identified to apply an excess of mandrel bars from pqf mill in mandrel mill. however, the hardness specified to Mandrel mill is higher than pqf mill due to surface treatment performed on mandrels surface in jeceaba (chroma). the challenge is to increase the hardness of x35 material homogeneously since the surface down to the core. focusing on increasing hardness in this 12 meters of round bar, a search was carried out to define the cooling process and partner to perform the treatment. oil was the most AGGRESSIVE way found in articles and suppliers datasheet. nevertheless, to treat this length is not usual and no partner was identified to carry out the treatment. so, An idea raised up from the technical team in charge of tooling. The idea was to carry out the heat treatment using the Q&T line for tubes located in the same plant. the vallourec team specified the heat treatment with internal know-how and technical information taken from suppliers datasheet. this work will show details of this heat treatment and comparison of microstructures in each phase of the treatment. penetrating liquid (non destructive test) was also performed once the cracks are critical and undesirable in the application on the mill.

mandrel mill is a process used to manufacture seamless tubes. the process consists in 8 stands using 2 rolls in each stand reducing the outside diameter and one mandrel inside of the shell to keep the inside diameter. THE WALL THICKNESS of the tube IS the main result of this process. the pqf (premium quality finishing) has the same objective concerning wall thickness, but with high quality. vallourec has, in partnership with sumitomo, a pqf located at jeceaba. the mandrel from this process has the same material specification. an opportunity was identified to apply an excess of mandrel bars from pqf mill in mandrel mill. however, the hardness specified to Mandrel mill is higher than pqf mill due to surface treatment performed on mandrels surface in jeceaba (chroma). the challenge is to increase the hardness of x35 material homogeneously since the surface down to the core. focusing on increasing hardness in this 12 meters of round bar, a search was carried out to define the cooling process and partner to perform the treatment. oil was the most AGGRESSIVE way found in articles and suppliers datasheet. nevertheless, to treat this length is not usual and no partner was identified to carry out the treatment. so, An idea raised up from the technical team in charge of tooling. The idea was to carry out the heat treatment using the Q&T line for tubes located in the same plant. the vallourec team specified the heat treatment with internal know-how and technical information taken from suppliers datasheet. this work will show details of this heat treatment and comparison of microstructures in each phase of the treatment. penetrating liquid (non destructive test) was also performed once the cracks are critical and undesirable in the application on the mill.

Keywords

X35crmov5.1.1, Heat treatment, mandrel mill, pqf mill, mandrel bar

X35crmov5.1.1, Heat treatment, mandrel mill, pqf mill, mandrel bar