TPT March 2018

AR T I C L E

Shandong Province SiFang Technical Development Co, Ltd

Hardness HRC

Impact toughness kJ/m 2

Grade

Condition

Sampling direction Tensile strength MPa

D2

Quenching and tempering Quenching and tempering Quenching and tempering Stress release and tempering Quenching and tempering

Radial Radial Radial Radial Radial

733 751 750 548 705

31 30 35 40 32

59.5 58.2 57.7 57.3 60.1

X155CrVMo12-1

SKD11 ZCr20 ZCr15

Table 6: D2, X155CrVMo12-1,SKD11 and ZCr15, ZCr20 roll Tensile strength and impact toughness test result after dissecting the finished rolls

Abrasion loss (mg)

Sample number

X165CrMoV12

Cr12MoV

9Cr2Mo

GCr15 241.2 260.4 248.6 250.1

1 2 3

51.2 48.1 46.2 48.1

60.2 59.8 59.6 59.9

152.2 142.4 141.6 145.4

Average value

Table 7: Abrasion loss of several welded pipe roll samples

The test result of impact toughness of several kinds of welded pipe rolls made by Henan Science and Technology University and Xinxiang Kaidi Roll LLC. See Table 5. Test result of impact toughness after dissecting D2, X155CrVMo12-1, SKD11 and ZCr15. ZCr20 finished rolls made by Shandong Province Sifang Technical Development. See Table 6. Note: Because of the big difference of anisotropy for casting rolls, a radial sample is taken. 4.3 Comparison of wear resistance Test of wear resistance of several welded pipe rolls around the world made by Henan Science and Technology University and Xinxiang Kaidi Roll LLC. See Table 7. Shandong University and SDSF conducted wear resistance experiments for several domestic and imported welded pipe rolls. Result is as below.

The forged shaped roll – due to its special-shaped roll characteristics – is difficult to form and is generally forged using cylindrical roll blanks. A lot of energy is used in the process and a large amount of material, so savings are generally at around 40 per cent as the process has higher material and energy consumption. The casting of high-chromium roll manufacturing process, when compared with the same forging roll manufacturing process, has an excellent energy saving effect – saving 70 per cent of energy and 40 per cent of materials. The production of one ton can save 15.11 tons of standard coal during manufacture. The ZCr15, ZCr20, ZCr25 series forges high-chromium welded pipe roll using different heat treatments. The matrix is austenite or martensite, carbide is mainly M 7 C 3 ; the micro hardness can be up to 1,800Hv and is discontinuous, granular and chrysanthemum-like. Carbide content is about 20 per cent. GCr15, 9Cr2Mo and other matrixes are martensite, carbide is mainly M 3 C type and low content. Micro hardness is about 800Hv. D2, X155CrVMo121, SKD11 matrix is martensite. M 7 C 3 carbide content is about 15 per cent. So ZCr15, ZCr20, ZCr25 series cast high chromium rolls show higher wear resistance than the others during tests.

Note: all samples are from the finished rolls.

The results of experiments show that the wear resistance of casting high chromium alloy roll reached the level of rolls made from the materials of D2, X155CrVMo12-1 and SKD11.

4. Comparison of performance for several kinds of rolls 4.1 Comparison of hardness and hardenability

Dissection of D2, X155CrVMo12-1, SKD11 forging roll and ZCr15, ZCr20 casting roll hardness drop and depth test result of working layer. See Table 4. 4.2 Comparison of mechanical properties Comparison of the mechanical properties of several different rolls.

188

www.read-tpt.com

MARCH 2018