Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Daido Steel Co Ltd
Original Assignee
Daido Steel Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Daido Steel Co LtdfiledCriticalDaido Steel Co Ltd
Priority to JP13576480ApriorityCriticalpatent/JPS5762806A/en
Publication of JPS5762806ApublicationCriticalpatent/JPS5762806A/en
PURPOSE: To improve the heat-check resistance and the fire-crack resistance of a tool, and to extend the service life of the tool, by forming a chilled layer of a prescribed hardness into a prescribed depth in the surface layer of the tool, and by applying a temperaing process to this tool.
CONSTITUTION: A chilled layer in ≥3mm thicness is formed in the surface layer of a pipe forming tool; the hardness of this chilled layer is prescribed in 60W75 HS, or the said tool is subjected to a tempering process. Hereby, the heat-check resistance and the fire-crack resistance are improved, the amount of the rolled product is increased, the productivity is improved, and the working cost is reduced.