scholarly journals Enhancement of the Quality of the Shell-Core Bond Interface in Duplex Work Rolls Manufactured by Centrifugal Casting Used in Hot Strip Mills

Materials ◽  
2019 ◽  
Vol 12 (8) ◽  
pp. 1304 ◽  
Author(s):  
Alberto Cofiño-Villar ◽  
Florentino Alvarez-Antolin ◽  
Juan Asensio-Lozano
Keyword(s):  
Cast Iron ◽  
Impact Toughness ◽  
Centrifugal Casting ◽  
Complete Fusion ◽  
The Core ◽  
Hot Strip ◽  
Bond Interface ◽  
Hot Strip Mills ◽  
The Impact ◽  
Work Rolls

To ensure the formation of a sound shell-core bond interface free of defects between the shell and the core in work rolls used in the finishing stands of hot strip mills, a complete fusion of this interface must be achieved, avoiding excessive mixing of the two components and the formation of hard, fragile microstructures. The shell is made of white cast iron, alloyed with Ni and Cr, and the core is manufactured of grey cast iron spheroidal graphite in a pearlitic matrix. It is thus advisable to inoculate the shell with 0.6 kg/T SiCaMn, as this promotes discontinuity in the carbide network and leads to an increase in the impact toughness of the bond interface. Furthermore, inoculation of the shell with FeSi-La should be avoided, as this inoculant leads to an increase in graphite counts, promoting it with a lamellar morphology at the edge of the bond and hence reducing the impact toughness in this interface. Addition of Mg to the shell has been found to produce an increase in hardness in the regions adjacent to the bond interface.

scholarly journals Improvement in the Resistance to Wear of Work-Rolls Used in Finishing Stands of the Hot Strip Mills

Metals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1873
Author(s):  
Alberto Cofiño-Villar ◽  
Florentino Alvarez-Antolin ◽  
Carlos Hugo Alvarez-Perez
Keyword(s):  
Cast Iron ◽  
White Cast Iron ◽  
Outer Zone ◽  
Spheroidal Graphite ◽  
Hot Strip ◽  
Eutectic Constituent ◽  
Grey Cast ◽  
Resistance To Wear ◽  
Hot Strip Mills ◽  
Work Rolls

Work-rolls manufactured through the Indefinite Chill Double Poured (ICDP) method present an exterior work layer manufactured in a martensitic white cast iron alloyed with 4.5 %Ni, 1.7 %Cr, and 0.7 %Nb (wt.%). In its microstructure, there are abundant carbides of the type M3C and MC, which give high resistance to wear, and graphite particles which improve the service behaviour of the rolls against thermal cycling. The core of the rolls is manufactured in grey cast iron of pearlitic matrix and spheroidal graphite. These work-rolls are used in the finishing stands in Hot Strip Mills for rolling slabs proceeding from continuous casting at 1200 °C. Through the application of a Design of Experiments (DoE), an attempt has been made to identify those manufacturing factors which have a significant effect on resistance to wear of these rolls and to find an optimal combination of levels of these factors which allow for improvement in resistance to wear. To increase resistance to wear, it is recommended to situate, simultaneously, the liquidus temperature and the percentage of Si in the respective ranges of 1250–1255 °C and 1.1–1.15 (wt.%). Higher liquidus temperatures favour the presence of the pro-eutectic constituent rather than the eutectic constituent. The outer zone of the work layer, in contact with the metal sheet, which is being rolled, does not show the graphitising effect of Si (0.8–1.15 wt.%). On the contrary, it confirms the hardening effect of the Si in solid solution of the ferrite. The addition of 0.02% of Mg (wt.%) and the inoculation of 6 kg/T of FeB tend to eliminate the graphitising effect of the Si, thus favouring that the undissolved carbon in the austenite is found to form carbides in contrast to the majority formation of graphite.

scholarly journals Laser Surface Hardening of Ni-hard White Cast Iron

Metals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 795
Author(s):  
Samar Reda Al-Sayed ◽  
Ahmed Magdi Elshazli ◽  
Abdel Hamid Ahmed Hussein
Keyword(s):  
Wear Resistance ◽  
Cast Iron ◽  
Impact Toughness ◽  
Surface Hardening ◽  
White Cast Iron ◽  
Laser Surface ◽  
Hard Alloys ◽  
The Core ◽  
Laser Surface Hardening ◽  
The Impact

Laser surface treatment on two different types of nickel–chromium white cast iron (Ni-hard) alloys (Ni-hard 1 and Ni-hard 4) was investigated. Nd:YAG laser of 2.2-kw with continuous wave was used. Ni-hard alloys are promising engineering materials, which are extensively used in applications where good resistance to abrasion wear is essential. The conventional hardening of such alloys leads to high wear resistance nevertheless, the core of the alloy suffers from low toughness. Therefore, it would be beneficial to harden the surface via laser surface technology which keeps the core tough enough to resist high impact shocks. A laser power of different levels (600, 800 and 1000 Watts) corresponding to three different laser scanning speeds (3, 4 and 5 m·min−1) was adopted hoping to reach optimum conditions for wear resistance and impact toughness. The optimum condition for both properties was recorded at heat input of 16.78 J·mm−2. The present findings reflect that the microhardness values and wear resistance clearly increased after laser hardening by almost three times due to laser surface hardening, whereas, the impact toughness was increased from five joules obtained from conventionally heat-treated samples to 6.4 J as gained from laser-treated samples.

scholarly journals Effect of MC Type Carbides on Wear Resistance of High Wear Resistant Cast Iron Rolls Developed for Work Rolls of Hot Strip Mills

2020 ◽  
Vol 106 (12) ◽  
pp. 883-891
Author(s):  
Kazunori Kamimiyada ◽  
Shinya Ishikawa ◽  
Hirofumi Miyahara ◽  
Yuji Konno
Keyword(s):  
Wear Resistance ◽  
Cast Iron ◽  
Wear Resistant ◽  
Hot Strip ◽  
Hot Strip Mills ◽  
Work Rolls

Thermal stresses in the work rolls of hot-strip mills

Metallurgist ◽  
2009 ◽  
Vol 53 (9-10) ◽  
pp. 560-564
Author(s):  
L. S. Kokhan ◽  
A. V. Aldunin ◽  
N. A. Farunda ◽  
L. M. Semenova
Keyword(s):  
Thermal Stresses ◽  
Hot Strip ◽  
Hot Strip Mills ◽  
Work Rolls

Study on the Influence of High Temperature Homogenizing and Solution on the Microstructure and Property of 4Cr5MoSiV1 Steel

2012 ◽  
Vol 549 ◽  
pp. 567-571
Author(s):  
Luo Yi
Keyword(s):  
High Temperature ◽  
Chemical Composition ◽  
Impact Toughness ◽  
Thermal Fatigue ◽  
Fatigue Behavior ◽  
Fatigue Property ◽  
Eutectic Carbides ◽  
The Core ◽  
Thermal Fatigue Behavior ◽  
The Impact

4Cr5MoSiV1 steel, a widely used for hot work mould, contains Cr, Mo, V alloying elements that easily form carbides. The Micro-area chemical composition, microstructure, impact toughness and thermal fatigue behavior of 4Cr5MoSiV1 and 4Cr5MoSiV1H steels were investigated, the latter was carried on high temperature homogenizing and solution based on the former. The results showed that bulk eutectic carbides and elements segregation contained in the 4Cr5MoSiV1 steel reduced the impact toughness. But the impact toughness of the core of the mould steel block and thermal fatigue property of 4Cr5MoSiV1H steel were improved because the elements segregation and eutectic carbides was eliminated through the high temperature homogenizing and solution.

scholarly journals MICROSTRUCTURE AND PROPERTIES OF HIGH CHROMIUM WHITE CAST IRONS ALLOYED WITH BORON

2021 ◽  
Vol 3 ◽  
pp. 137-141
Author(s):  
Julieta Kaleicheva ◽  
Krasimir Kirov ◽  
Valentin Plamenov Mishev ◽  
Zdravka Karaguiozova
Keyword(s):  
Mechanical Properties ◽  
Cast Iron ◽  
Impact Toughness ◽  
Boron Content ◽  
Bending Strength ◽  
White Cast Iron ◽  
Metallographic Analysis ◽  
Cast Irons ◽  
High Chromium ◽  
The Impact

The microstructure and mechanical properties of high chromium white cast iron with composition: 2,6÷3,4% C; 0,9÷1,1% Si; 0,8÷1,1% Mn; 1,0÷1,3% Mo; 12,3÷13,4% Cr, additionally doped with boron in an amount of 0,18% to 1,25% is investigated. The microstructure of six compositions of white cast irons is studied by means of an optical metallographic analysis - one without boron, and the others contain 0,18%; 0,23%; 0,59%; 0,96% and 1,25% boron. A test is performed to determine: hardness by the Rockwell method; microhardness; bending strength and impact toughness. It was found that at a boron content of 0,18%; 0,23% and 0,59%, the structure of white cast irons is subeutectic, with impact toughness in the range of 1,80÷1,52 J/cm2; with a boron content of 0,96%, the structure of white cast iron is close to the eutectic, with impact toughness 0,98 J/cm2 ; at a boron content of 1,25% the structure of white cast iron is supereutectic and the impact toughness decreases to 0,68 J/cm2. With a change in the boron content from 0,8% to 1,25%, the amount of carbide phase in the structure of white cast iron increases, which leads to an increase in hardness from 53 to 59 HRC. The highest bending strength (Rmi=660,85 MPa) was obtained in white cast irons with a boron content of 0,23%. 

Sign in / Sign up

Export Citation Format

Share Document