How to choose wear-resisting lining board, screen board material and heat treatment technology?
(1) heat treatment process of sieve plate of high chromium cast iron sinter?
Sinter sieve plate is working under severe conditions of abrasive wear, consumption, import the service life of the sieve plate, about 60 days, homemade sieve plate, about 40 days, mainly due to the low domestic sieve plate hardness, eutectic carbide quantity is less, particle rough, uneven distribution, in a large number of sinter under the constant collision and friction of sieve plate tissue deformation, furrow pit, crack and hemp. Chemical composition (mass fraction) : C: 2.84%, Cr: 20.44%, Mn: 1.37%, Cu: 0.92%, Si: 0.67%,? Mn: 0.8%, S: 0.024%, P: 0.03%. The as-cast microstructure is gray-white residual austenite + martensite + white eutectic carbide distributed in large blocks or dendrites. The heat treatment can obviously refine the as-cast microstructure, improve the surface hardness, wear resistance and toughness of the casting. Heat treatment at 1000 ℃ x2h quenching + 250 ℃ x2h tempering, 60 ~ 63 HRC hardness, impact toughness of 13.14 ~ 17.30 J/c ㎡. After wear test comparison, the average import sieve plate of 4.66 mg, the original domestic sieve plate weightlessness on average 5.55 mg, 4.59 mg. The new material sieve plate weightlessness on average 4.59 mg. The service life of the new material sieve plate is more than 60 days.
(2) medium manganese white cast iron lining heat treatment
Typical alloy composition (mass fraction) of medium manganese white cast iron: Mn: 4.0%~5.0%, Cr: 1.5%~2.0%, Mo: 0.5%~1.0%, Cu: 1.0%~1.5%. This is because the columnar crystal size of cast iron alloy increases with the increase of manganese content. The high manganese content alloy must be tempered at high temperature after quenching, so that the precipitated secondary carbide particles have obvious focusing and coarsening during the tempering process. After the increase of manganese content, because a large amount of residual austenite after quenching occurs martensite transformation in the process of high temperature tempering, the alloy with high manganese content has greater phase change stress after high temperature tempering than low temperature tempering. Therefore, the content of manganese in white manganese cast iron should be controlled at about 0.3%. Type M23Cr2Mo low alloy white cast iron made of 950 ~ 960 ℃ x2h air cooling quenching, martensite structure. By 250 ℃ x2h to stress in low temperature tempering, 56 ~ 57 HRC hardness can be obtained, ak = 6.0 J/c ㎡. Used in a power plant ball mill lining board, surface smooth, uniform wear, no broken, wear resistance of high manganese steel lining plate of 2.32 times.
(3) ZG85Cr2MnMoRE ball mill lining heat treatment
Chemical composition of ZG85Cr2MnMoRE wear-resistant steel (mass fraction) : C: 0.8% ~ 0.9%, SI: 0.2% ~ 0.45%, Mn: 0.6% ~ 1.0% and Cr: 2.0% ~ 2.5%, Mo: 0.3% ~ 0.5%, RE: 0.5%, P, S acuities were 0.045% and 0.04% or less. The heat treatment process: 850 ~ 860 ℃ heating oil quenching, 500 ~ 550 ℃ tempering, quenching heat insulation coefficient calculated by 1.2 ~ 1.5 mm/min, tempering heat coefficient calculated by 2 min/mm). Liner steel has the best overall performance. 48 ~ 52 HRC 550 ℃ tempering, the hardness, impact toughness of 34.5 J/c ㎡. Organization of sorbite and austenite.
(4) ZG42Cr2MnSi2MoCe ball mill lining heat treatment
The liner plate of large ball mill is made of ZG42Cr2MnSi2MoCe steel. In pit type furnace is 840 ~ 860 ℃ heating, quenching oil, 280 ~ 300 ℃ tempering. C: 0.47%, Cr: 1.80%, Mn: 1.40%, Si: 1.60%, Mo: 0.3%, P 0.025%, S 0.022%, Ce proper amount.
The steel after heat treatment, sigma b = 1746 mpa, ak = 22 j/c ㎡. 55.5 HRC hardness, microstructure for M + AR4.9, sulfate particles fine garden, uniform distribution.
ZG42CrMnSiMoCe steel wear-resistant steel than without Ce, sigma b increased from 1648 mpa to 1746 mpa, ak value from j/c ㎡. 17 to 22 j/c ㎡., hardness increased from 53 HRC to 55 HRC. Its service life than ZGMn13 steel.
(5) ZGMn13 high manganese steel liner heat treatment improvement process
Lining board of large ball mill, wall thickness ranging from 22 mm to 170mm, weight around 300~600kg, severe oxidation and decarbonization of casting, long heating time, waste of energy. The improved process, shorten the heating time in half, and mechanical performance is improved, sigma b increased from 689.25 MPa to 788.9 MPa, sigma b increased from 18.0% to 29.6%, ak by 62.23 J/c ㎡. Increase to 136.71 J/c ㎡.
(6) 42CrMnSiMoVB under the bainitic - martensite wear steel
42 crmnsimovb steel after 875 ℃ is fire, 450 ℃ tempering hardness can be obtained 50.6 HRC, A = 17.0 J impact work, sigma b = 1725 MPa, the delta 5 = 9%, ￠= 25.2% bedplate of hydraulic press and skateboard original using 5 crmnmo steel, wear resistance is poor, only use 3 weeks; The service life of 42CrMnSiMoVB steel is increased more than 3 times.