Development of a new multi-component white cast iron for cold work roll

Research Project

Project/Area Number	14550730
Research Category	Grant-in-Aid for Scientific Research (C)
Allocation Type	Single-year Grants
Section	一般
Research Field	Metal making engineering
Research Institution	Kurume National College of Technology
Principal Investigator	SASAGURI Nobuya Kurume National College of Technology, Materials Science and Metallurgical Engineering, Professor, 材料工学科, 教授 (50215737)
Co-Investigator(Kenkyū-buntansha)	MATSUBARA Yasuhiro Kurume National College of Technology, Materials Science and Metallurgical Engineering, Professor, 材料工学科, 教授 (20044258)
Project Period (FY)	2002 – 2003
Project Status	Completed (Fiscal Year 2003)
Budget Amount *help	¥3,000,000 (Direct Cost: ¥3,000,000) Fiscal Year 2003: ¥1,600,000 (Direct Cost: ¥1,600,000) Fiscal Year 2002: ¥1,400,000 (Direct Cost: ¥1,400,000)
Keywords	Multi-component white cast iron / MC carbide / M2C carbide / Solidification structure / continuous cooling transformation / heat treatment / abrasive wear / Roll material / 焼戻し / 連続冷却変形 / マルテンサイト / ベイナイト / パーライト / 二次硬化 / M7C3炭化物 / デンドライト間隔
Research Abstract	In order to develop a new multi-component white cast iron for cold work roll, the optimum chemical compositions were investigated, and the relationship between the solidification structure and the solidification conditions, and the characteristics of transformation and heat treatment, and abrasion wear characteristics were examined about the cast iron with the optimum chemical compositions. Following chemical composition is recommended as the optimum chemical composition. Carbon content is 1-1.5%. Chromium content is 5%. Molybdenum content is 5% or more. Vanadium content is 1% or more. The cast irons with optimum chemical compositions contain MC and M_2C eutectic carbides of 9% to 12%. Solidification structure of the cast irons depends on the cooling rate, and the secondary dendrite arm spacing and sizes of MC and M_2C carbides, which are shown as a function of the cooling rate, become smaller with an increase in cooling rate. Martensite and retained austenite coexist in the cast irons in hardened state because Mf was not observed in the cast irons. The hardnabihty of the cast irons is good because the noses of pearlite and bainite transformation are on a long time side. The curves of temper hardness of the cast irons show the secondary hardening which is usually seen in highly alloyed tool steels and multi-component white cast irons with high carbon, and the tempered hardness of the cast irons reached the maximum value(about 850HV) at around 800K. It's hardness is higher than the necessary hardness (800HV) for cold work roll. It is thought from the results of suga abrasion wear tests that abrasion wear resistance of the cast irons is somewhat lower than that of the multi-component white irons with high carbon.