TPT May 2014

Article

Shandong Province SiFang Technical Development Co, Ltd

The roll materials are mainly America’s D2, H13; Germany’s X155CrVMo121, X40CrMoV5-1; and Japan’s SKD11 and SKD61. But the technical difficulty to produce high quality and large- medium size roll was not always solved at home. If adopting a method imported fromabroad, the price cost is high and delivery cycle is long; if adopting a method of using Cr12Mo1V1 forging steel roll, possessed of the same chemical composition as foreign roll, the questions included less production plant, low product quality and inability produce large size roll at home; if adopting low grade forging steel roll, the questions included reducing service life of roll and influencing product quality. In this case at the end of the 20 th century and early 21 st century the status of imported roll replaced by high chromium alloy casting roll was appeared at home and the high chromium alloy casting roll was up to high grade imported roll level compared with American, German and Japanese rolls. Such, the high chromium alloy casting roll manufactured and developed by Shandong Province Sifang Technical Development Co. Ltd (SDSF), in which forging steel roll was replaced by casting roll, achieved success. 3. Different material analysis for roll of welding steel pipe and cold roll formed steel 3.1. GCr15 forging roll In history most welding steel pipe plants in our country selected GCr15 material to make forming and sizing rolls. Because of having low price and easy production so that it can make some small size roll and because of having poor hot crack resistance and spall resistance, specially small forging ratio, unsuitable heating treatment condition and high inclusion content in steel the crack and pointed corrosion are apparent in the surface of rolls.

In the standard of “the technical specification of welding steel pipe roll YB/T128-1997” formulated by China, the roll material is selected GCr15, Cr12, Cr12MoV, 35CrMoV, 40Cr, 4Cr5MoSiV1, 3Cr2W8V and 65Mn, and although Cr12MoV and 4Cr5MoSiV1 are also listed in the standard they are actually rarely used due to various reasons. Roll materials such as GCr15, 40Cr, 3Cr2W8V, 42CrMo are still used a lot [1] . The chemical composition of roll listed in this standard is shown in table 1. In the standard of “general technical specification of cold rolling working forged steel roll, GB/T 13314-2008” formulated by China, the selected roll material is 9Cr2, 8Cr2Mo, 9Cr2Mo, 9Cr2MoV 9Cr3Mo, 8Cr2MoV and 8Cr5MoV. The roll material mentioned above is mainly suitable for cold rolling working roll and intermediate roll forged by whole alloy steel for cold rolling plate and strip mills. The roll material is also used in welding steel pipe and cold roll formed steel roll. The chemical composition of roll listed in this standard is shown in table 2. 2. Bringing about roll innovation by new development of welding steel pipe and cold roll formed steel industry Entering after 21 st century the natural gas pipeline construction which “west gas transporting toward east pipeline engineering” is as a symbol and the refined oil pipeline construction which “south-west refined oil engineering” is as a symbol promoted a new development of steel pipe industry at home. A lot of ERW welding pipe mills with large-medium sizes were introduced from abroad, such as Tianjin Steel Pipe Company, Shanghai Baoshan Iron and Steel Company, Shandong Shengli Oil Field, Panyu Zhujiang Steel Pipe Company and so on. These introduced production lines bring about a lot of high alloy forging steel roll made from new material.

GmbH & Co KG

Table 2: The steel and its chemical composition of cold rolling working forged steel roll

Chemical Composition (Mass fraction%)

Steel

C

Si

Mn

Cr

Mo

V

Ni

Cu

S

P

0.80~ 0.95 0.80~ 0.90

1.30~ 1.70 1.80~ 2.40

9Cr2

≤0.40

≤0.40

–

–

–

–

≤0.030

0.15~ 0.40

0.30~ 0.50

0.20~ 0.40 0.20~ 0.40 0.20~ 0.30 0.20~ 0.40 0.20~ 0.60 0.20~ 0.60

0.05~ 0.15

8Cr2MoV

9Cr2Mo

–

1.70~ 2.10

≤0.25

≤0.025

0.85~ 0.95

0.25~ 0.45

0.20~ 0.35

0.10~ 0.20

9Cr2MoV

2.50~ 3.50 2.80~ 3.20 4.80~ 5.50

9Cr3Mo

–

0.78~ 1.10 0.78~ 0.90

0.40~ 1.10 0.40~ 1.10

0.20~ 0.50 0.20~ 0.50

0.05~ 0.15 0.10~ 0.20

8Cr3MoV

≤0.025

≤0.80

≤0.25

8Cr5MoV

≤0.020

92

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May 2014