Material Introduction:
Cast iron rolls can be classified into two types based on their matrix structure. One type is pearlite cast iron with graphite and carbides distributed on the pearlite matrix. The other type is bainite cast iron rolls, where graphite and carbides are distributed on the bainite matrix.
The outer material structure of pearlite cast iron rolls consists of a pearlite matrix with spherical graphite and carbides distributed on it. By appropriately controlling the chromium content, chromium alloyed pearlite cast iron rolls can be obtained. These rolls belong to a type of pearlite cast iron and the chromium alloying can increase the penetration depth of carbides. Compared to ordinary cast iron rolls, this type of rolls have a much lower hardness variation and are particularly superior in wear resistance on rolls with deep grooves.
The outer material structure of bainite cast iron rolls consists of a bainite matrix with spherical graphite and carbides distributed on it. The bainite material has a higher alloying degree than the pearlite material. At the same hardness, bainite cast iron rolls are more wear-resistant than pearlite cast iron rolls. However, pearlite cast iron rolls have better resistance to thermal cracking than bainite cast iron rolls.
Chemical Composition:
|
Classification |
Material code |
C |
Si |
Mn |
P |
S |
Ni |
Cr |
Mo |
Mg |
|
Pearlitic spheroidal graphite cast iron roller (I) |
SGPI |
2.9 / 3.6 |
1.4 / 2.2 |
0.4 / 1.0 |
≤0.15 |
≤0.03 |
1.5 / 2.0 |
0.1 / 0.6 |
0.2 / 0.8 |
＞ 0.04 |
|
Pearlitic spheroidal graphite cast iron rolls (II) |
SGPII |
2.9 / 3.6 |
1.2 / 2.0 |
0.4 / 1.0 |
≤0.15 |
≤0.03 |
2.0 / 2.5 |
0.2 / 1.0 |
0.2 / 0.8 |
＞ 0.04 |
|
Pearlitic spheroidal graphite cast iron rolls (III) |
SGPIII |
2.9 / 3.6 |
1.0 / 2.0 |
0.4 / 1.0 |
≤0.15 |
≤0.03 |
2.5 / 3.0 |
0.2 / 1.2 |
0.2 / 0.8 |
＞ 0.04 |
|
Pearlitic ductile cast iron roller (I) |
SGAI |
2.9 / 3.6 |
1.2 / 2.2 |
0.2 / 0.8 |
≤0.10 |
≤0.03 |
3.0 / 3.5 |
0.2 / 1.0 |
0.5 / 1.0 |
＞ 0.04 |
|
Pearlitic ductile cast iron rolls (II) |
SGAII |
2.9 / 3.6 |
1.2 / 2.0 |
0.2 / 0.8 |
≤0.10 |
≤0.03 |
3.5 / 4.5 |
0.3 / 1.5 |
0.5 / 1.0 |
＞ 0.04 |
Mechanical properties:
|
Classification |
Roll body hardness (HSD) |
Roll neck hardness (HSD) |
Tensile strength (MPa) |
|
Pearlitic malleable cast iron rolls (I) |
45〜55 |
35〜55 |
＞ 450 |
|
Pearlitic malleable cast iron rolls (II) |
55〜65 |
35〜55 |
＞ 450 |
|
Pearlitic spheroidal graphite cast iron rolls (III) |
62〜72 |
35〜55 |
＞ 450 |
|
Bainitic ductile cast iron rolls (I) |
55〜78 |
32〜45 |
＞ 350 |
|
Pearlitic ductile cast iron rolls (II) |
60〜80 |
32〜45 |
＞ 350 |
Metallic structure:
|
Classification |
Organization |
|
Pearlitic spheroidal graphite cast iron roller (I) |
Pearlite + Carbide + A small amount of Ferrite |
|
Pearlitic spheroidal graphite cast iron rolls (II) |
Pearlite + Carbide + A small amount of Ferrite |
|
Pearlitic spheroidal graphite cast iron rolls (III) |
Pearlite + Carbide + A small amount of Ferrite |
|
Pearlitic ductile cast iron roller (I) |
Bainite + Carbide + SG |
|
Pearlitic ductile cast iron rolls (II) |
Bainite + Carbide + SG |
Application
|
Designation of rolls |
Application |
|
Pearlitic nodular cast iron rolls（I） |
The roughing machine stands of the bar rolling machine and the wire rod rolling machine |
|
Pearlitic nodular cast iron rolls （II） |
The roughing machine stands of the bar rolling machine and the wire rod rolling machine |
|
Pearlitic nodular cast iron rolls（III） |
The roughing machine stands of the bar rolling machine and the wire rod rolling machine |
|
Bainitic nodular cast iron rolls （I） |
The roughing machine stands of the bar rolling machine and the wire rod rolling machine |
|
bainitic nodular cast iron rolls （II） |
The roughing machine stands of the bar rolling machine and the wire rod rolling machine |