TPT May 2014

Article

Shandong Province SiFang Technical Development Co, Ltd

Chemical composition (mass fraction%)

Remark

Steel

P

S

C

Si

Mn

Cr

Ni

Mo

W V Standard No.

≤

0.95~ 1.05

0.15~ 0.35

0.25~ 0.45 0.025 0.025 1.40~ 1.65

GCr15

≤0.30

GB/T 18254

2.00~ 2.30 ≤0.40 ≤0.40 0.030 0.030 11.50~

Cr12

GB/T1299

13.00 ≤0.25

0.15~ 0.30 0.10~ 0.20

Cr12MoV 1.45~

GB/T1299

1.70 ≤0.40 ≤0.40 0.030 0.030 11.00~

12.50 ≤0.25 0.40~ 0.60

0.17~ 0.37 0.17~ 0.37 0.80~ 1.20

0.40~ 0.70 0.035 0.035 1.00~ 1.30 0.50~ 0.80 0.035 0.035 0.80~ 1.10 0.20~ 0.50 0.030 0.030 4.75~ 5.50

35CrMoV 0.30~ 0.38

≤0.30 0.20~ 0.30

GB/T3077

0.37~ 0.44

40Cr

≤0.30

GB/T3077

0.80~ 1.20 0.20~ 0.50

4Cr5MoSiV1 0.32~ 0.45

≤0.25 1.10~ 1.75

GB/T1299

7.50~ 9.00

3Cr2W8V 0.30~

≤0.25

GB/T1299

0.40 ≤0.40 ≤0.40 0.030 0.030 2.20~ 2.70

0.62~ 0.70

0.17~ 0.37

0.90~ 1.20 0.035 0.035 ≤0.25 ≤0.25

65Mn

GB/T1222

Table 1: Chemical composition of welding steel pipe roll

1.1.2. Possessed of enough strength and toughness If the roll has only high wear resistance and hardness but not excellent strength and toughness, the roll will produce break and crash in used to influence the reliability and safety of roll. 1.1.3. Possessed of certain cold workability and heat workability The cold working includes lathe working, grinder working, miller working, etc. and the heat working includes casting, forging and heat treating process. 1.1.4. Other requirements The working roll located at special condition must be possessed of certain red hardness, heat strength and speedily chilling and heating resistance. 1.2. Present situation on roll material for welding steel pipe and cold roll formed steel The design of the roll is a basic part of the design of welding pipe and cold roll formed steel mills. The design of the roll mainly includes two aspects. First is the design of pass and structure of roll; second is the design of material of roll, and there is not lack of both. If the excellent combination of two parts the service life of roll can be lengthened, the consumption of roll can be reduced, the productivity can be increased and the product quality can be ensured. Because of having the same formed method and production process between welding steel pipe and cold roll formed steel, the selected roll material is basically the same. At present the traditional designed roll material for HFW/FRW welding pipe and cold roll formed steel at home and abroad is alloy forging steel material. In America it is D2, H13; Germany uses X155CrVMo121, X40CrMoV5-1; Japan uses SKD11, SKD61; China uses Cr12MoV, 3Cr2W8V, Cr12, 9Cr2Mo, GCr15, 42CrMo.

said good material should be possessed of specially working environment and process requirement and appropriate working condition. The wear resistance of material is not only depending on the material itself but also has great relationship with wear resistance environment. For the same material, it can produce bigger difference to wear resistance in the different wear resistance system. In differently working environment it is necessary to use different rolls with different material composition. Under the different working condition the material composition of roll should also be different. The different working stands in same mill, such as extruding, sizing, strengthening, etc, have different working conditions, so the material composition of rolls should also be different. When researching and developing a new tool it is necessary to adapt to the working environment and process requirement of the tool and to reach an ideal state. When selecting material composition must be to consider as following: 1.1.1. High wear resistance and suitable hardness The wear resistance of material is not only depending on its macro-hardness but also on its micro-structure including the kinds of hard carbide, number, shape and distribution state, and its matrix strength and toughness. The metal material hardness decides resistance capability of surface deformed. For different materials with same hardness, some easy producing particle spall and some without this case are decided by strength and toughness of material matrix and the kinds of carbide. For possessed of same hardness material, high carbide hardness and excellent matrix strength and toughness possess better wear resistance. The hardness of roll is required to have uniform surface hardness and same hardness between inner and outer working layers. The specific hardness value should be decided by using place of roll. The wear resistance and hardness of roll surface are not only influencing service life of roll but also size, shape and surface quality of rolled steel products.

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May 2014