Nippon Steel Sumitomo Metal Corporation

Toho Titanium Co., Ltd.

Yoshimasa Miyazaki

Kazuhiro Takahashi

Hisamune Tanaka

Takashi Oda

Kenichi Mori

Hideki Fujii

Yoshihiro Fujii

Tomonori Kunieda

Hiroaki Otsuka

Norio Yamamoto

Osamu Tada

Takeshi Shiraki

A titanium slab is appropriate for hot rolling, is produced by electron beam melting furnace, has superior linearity so that it can be fed into a hot rolling machine without performing breaking down process or other subsequent correcting process after production, and has good structure having no cracks at the corner parts. A process for production thereof is also provided. The titanium slab is directly produced by a mold of an electron beam melting furnace, and has the deformation of not more than 5 mm for the thickness direction versus the longitudinal direction and deformation of not more than 2.5 mm for the width direction versus the longitudinal direction, both per a length of 1000 mm of the slab. The process for production of this titanium slab for hot rolling has a step of using an electron beam melting furnace in which its rectangular mold has mold walls of a long side and mold walls of a short side, and a step of pouring molten metal from one of the mold walls of a short side. Furthermore, a mold having chamfered parts at the corner parts can be used in the process.

Titanium slab for hot rolling produced by electron-beam melting furnace, process for production thereof, and process for rolling titanium slab for hot rolling

The present invention provides a titanium slab for hot rolling which can be fed into a general purpose hot-rolling mill for producing strip coil, without passage through a breakdown process such as blooming or a straightening process, and can further suppress surface defect occurrence of the hot-rolled strip coil, and a method of producing and a method of rolling the same, characterized in that in the cast titanium slab an angle &#x3b8; formed by the crystal growth direction (solidification direction) from the surface layer toward the interior and a direction parallel to the slab casting direction (longitudinal direction) is 45 to 90&#xb0;, and moreover, there is a surface layer structure of 10 mm or greater whose &#x3b8; is 70 to 90&#xb0;, and further characterized in that a crystal grain layer of 10 mm or greater is formed whose C-axis direction inclination of a titanium &#x3b1; phase is, as viewed from the side of the slab to be hot rolled, in the range of 35 to 90&#xb0; from the normal direction of the surface to be hot rolled. The titanium slab concerned is produced using an electron beam melting furnace by casting at an extraction rate of 1.0 cm/min or greater.

Titanium slab for hot rolling, and method of producing and method of rolling the same

The present invention provides a titanium material for hot rolling which enables reduction of defects on the surface (in the case of a flat material or strip coil, including not only the flat surfaces but also the side surfaces and edges) due to hot rolling. The titanium material for hot rolling has dimples imparted by cold plastic deformation whose mean value of the heights (Wc) of the undulation profile elements is 0.2 to 1.5 mm and mean value of the lengths (WSm) thereof is 3 to 15 mm. The invention also provides a method of producing the titanium material and a method of hot rolling the titanium material.

Titanium material for hot rolling and method of producing the same

Growing community of inventors

Tokyo, Japan

Yoshimasa Miyazaki