- #1. A forged roll for rolling comprising a high
carbon alloy cast steel metallurgical structure comprising about
1.10-1.85 wt % carbon, about 0.3-1.2 wt % silicon, about 0.4-1.5 wt %
manganese, about 0.5-2.0 wt % nickel, about 0.5-2.0 wt %
chromium and the remaining portion substantially iron, forged roll
for rolling mill comprising a multiplicity of particles of a spheroidal carbide
dispersed in the matrix of fotged roll, said particles having an average
diameter of about 1 to 2 μm, forged roll having a surface wherein said spheroidal carbide particles cover about 35-55% of the area of said
roll metallurgical structure.
#2. The forged roll as per #1, wherein at least one of about
0.1-1.0 wt % molybdenum, about 0.1-1.0 wt % vanadium and about 0.1-1.0
wt% tungsten is present in said high carbon alloy cast steel.
#3. Forged roll as per #1, containing
detrimental-to-forging elements, selected from the group consisting of
phosphorus, sulfur, copper, arsenic, tin, lead, zinc, antimony and
bismuth, and wherein the total content of said elements is 0.2 wt % or
less.
#4. Forged roll as per #2, containing
detrimental-to-forging elements, selected from the group consisting of
phosphorus, sulfur, copper, arsenic, tin, lead, zinc, antimony and
bismuth, and wherein the total content of said elements is 0.2 wt % or
less.
#5. Forged roll as per #1, wherein forged roll has a
matrix of a metallurgical structure which is 90 % area or more
occupied with a ferrite structure, and wherein said carbide whose
diameter ranges from about 1 to 2 μmφ is dispersed in said matrix of
said ferrite structure.
#6. Forged roll as per #2, wherein said roll has a
matrix of a metallurgical structure which is 90% area or more occupied
with a ferrite structure, and wherein said carbide whose diameter
ranges from about 1 to 2 μmφ is dispersed in said matrix of said
ferrite structure.
#7. Forged roll as per #1, said roll comprising an
amount of coarse bar or bulk carbide distributed over at most about 3
% by area of the metallurgical structure.
#8. Forged roll as per #2, said roll comprising an
amount of coarse bar or bulk carbide distributed over at most about 3%
by area of the metallurgical structure.
#9. Forged roll as per #1, having a surface hardness
which ranges from about 29 to 34 Hs.
#10. Forged roll as per #2, having a surface hardness
which ranges from about 29 to 34 Hs.
#11. A forged roll or rolling a seamless steel pipe, comprising a high
carbon alloy cast steel which comprises about 1.10-1.85 wt % carbon,
about 0.3-1.2 wt % silicon, about 0.4-1.5 wt % manganese, about
0.5-2.0 wt % nickel and about 0.5-2.0 wt % chromium and a remaining
portion substantially consisting of iron, made by a method wherein
said roll is hot-forged so as to be roll-shaped, said roll is cooled
down to about 600° C. or less at a cooling rate of about 2.5° C./min
or more, a first stage heat treatment for spheroidal carbide formation
is performed wherein said roll is maintained for about five hours or
more at
a temperature from about (Acm minus 10° C.) to (Acm minus 100° C.),
and a second stage heat treatment is performed for
spheroidal carbide formation to create a spheroidal carbide in said
roll, the roll metallurgical structure being about 35 to 55% area
occupied with said spheroidal carbide.
#12. A forged roll according to #11, wherein at least one of about
0.1-1.0 wt % molybdenum, about 0.1-1.0 wt % vanadium and about 0.1-1.0
wt % tungsten is present in said high carbon alloy cast steel.
#13. A forged roll according to #11, wherein the total content of
detrimental-to-forging elements of said high carbon alloy cast steel,
selected from the group consisting of phosphorus, sulfur, copper,
arsenic, tin, lead, zinc, antimony and bismuth, is 0.2 wt % or less.
#14. A forged roll according to #12, wherein the total content of
detrimental-to-forging elements of said high carbon alloy cast steel,selected from the group consisting of phosphorus, sulfur,
copper, arsenic, tin, lead, zinc, antimony and bismuth, is 0.2 wt % or
less.
#15. A forged roll according to #11, wherein said second stage
heat treatment for spheroidal carbide formation is performed at a
temperature range from about 700° to 840° C.
#16. A forged roll according to #12, wherein said second stage
heat treatment for spheroidal carbide formation is performed at a
temperature range from about 700° to 840° C.
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