CN-121976127-A - Microalloyed high-toughness martensitic stainless steel cutter disc, preparation method thereof and preparation mold

CN121976127ACN 121976127 ACN121976127 ACN 121976127ACN-121976127-A

Abstract

The invention discloses a microalloyed high-toughness martensitic stainless steel knife disc, a preparation method and a preparation mould thereof, wherein the stainless steel comprises the following components in percentage by weight, and the balance of Fe is ：C：0.3%~0.7%,Si：0.3%~1.0%,Mn：0.5%~1.5%,Cr：16%~18.5%,Ni：1%~2%,Mo：0.3%~0.8%,V：0.1%~0.35%,Nb：0.1%~0.25%,S：≤0.02%,P：≤0.02%,. Firstly smelting raw materials into molten iron, adding deoxidizing agent into the molten iron, casting coated sand, casting by adopting a sand mold to obtain a cutterhead blank, performing heat treatment on the cutterhead blank, and finally performing shot blasting and polishing on the cutterhead after heat treatment. The martensitic stainless steel cutter disc is provided with a metallographic structure with a martensitic structure as a main material and austenite as an auxiliary material, wherein CrC, VC and NbC particles are dispersed and distributed, the hardness of the metallographic structure is 40-45HRC, the impact toughness reaches 92-95J/cm 2 , the wear resistance and the service life of the cutter disc are longer, and compared with the cutter disc without alloy elements, the wear amount of the cutter disc is reduced by 70%.

Inventors

Niu Jiangting
Hou Liyue
ZHAO PING
Tian Yingpan
LI XIAOHAN
YANG CHANGLEI
GONG ZELONG
WANG RUI

Assignees

山东晨钟机械股份有限公司

Dates

Publication Date: 20260505
Application Date: 20260408

Claims (9)

1. A microalloyed high-toughness martensitic stainless steel cutterhead is characterized in that the stainless steel comprises ：C：0.3%~0.7%,Si：0.3%~1.0%,Mn：0.5%~1.5%,Cr：16%~18.5%,Ni：1%~2%,Mo：0.3%~0.8%,V：0.1%~0.35%,Nb：0.1%~0.25%,S：≤0.02%,P：≤0.02%, percent of Fe as the rest element according to weight percentage.
2. The microalloyed high toughness martensitic stainless steel cutterhead of claim 1, wherein the stainless steel comprises the balance of ：C：0.58%~0.7%,Si：0.5%~0.6%,Mn：0.8%~1.1%,Cr：17%~18.5%,Ni：1%~1.8%,Mo：0.5%~0.7%,V：0.1%~0.35%,Nb：0.1%~0.25%,S：≤0.02%,P：≤0.02%, by weight of Fe.
3. The microalloyed high toughness martensitic stainless steel cutterhead of claim 1, wherein the martensitic stainless steel cutterhead has a metallographic structure with mainly martensitic structure and secondarily austenite, and dispersed CrC, VC and NbC particles, the hardness of which is 37-45HRC, and the impact toughness of which is 92-95J/cm 2 .
4. A method of making a microalloyed high toughness martensitic stainless steel cutterhead in accordance with any one of claims 1-3, characterized by the steps of: (1) Smelting raw materials into molten iron, wherein the smelting temperature is 1620-1680 ℃, and the raw materials comprise ferrochrome, pig iron, ferromolybdenum, ferrovanadium, ferroniobium, ferromanganese and nickel plates; (2) Adding deoxidizing agent into molten iron, molding precoated sand, casting by adopting a sand mold, and pouring to obtain a cutterhead blank; (3) Carrying out heat treatment on the cutterhead blank prepared in the step (2), wherein the heat treatment process adopts an annealing, quenching and tempering three-section heat treatment process, wherein the annealing temperature is 620-750 ℃, the heat preservation is carried out for 2.5-4 hours, the quenching is carried out after the cutterhead blank is cooled to room temperature along with a furnace, the temperature is firstly increased to 620-750 ℃ and then is kept for 1.5-3 hours, the temperature is firstly increased to 820-880 ℃ and then is kept for 1-2 hours, the temperature is finally increased to 1020-1080 ℃ and is kept for 1.5-3 hours, the tempering treatment is carried out after the oil quenching is cooled to room temperature, the temperature is kept for 8-12 hours at 550-680 ℃, and the oil cooling is carried out to room temperature; (4) And (5) performing shot blasting and polishing on the cutterhead after the heat treatment.
5. A die for preparing a microalloyed high toughness martensitic stainless steel cutterhead according to any one of claims 1-3, and comprising a stack casting die and a vertical pouring gate, wherein the stack casting die comprises an upper sand mold, a middle sand mold and a lower sand mold, the upper sand mold, the middle sand mold and the lower sand mold are all in a fan-shaped structure, N middle sand molds are sequentially stacked between the upper sand mold and the lower sand mold, n+1 casting cavities are formed between the upper sand mold and the middle sand mold, between two adjacent middle sand molds and between the middle sand mold and the lower sand mold, the n+1 casting cavities are respectively communicated with the vertical pouring gate through inlets of the n+1 casting cavities, tooth surface structures are arranged on the lower surface of the upper sand mold, tooth back structures are arranged on the upper surface of the middle sand mold, tooth surface structures are arranged on the lower surface of the lower sand mold, any two tooth back structures are the same or different, and any two tooth surface structures are the same or different.
6. The mold for preparing the microalloyed high toughness martensitic stainless steel cutterhead in accordance with claim 5, wherein the vertical gates comprise an upper conical mouth and a lower cylindrical pouring channel, the bottom of the conical mouth is communicated with the top of the cylindrical pouring channel, a plurality of gates are arranged on the side surface of the cylindrical pouring channel, and the gates are respectively communicated with the inlets of the pouring cavities in an aligned manner.
7. The die for preparing the microalloyed high-toughness martensitic stainless steel cutter head as recited in claim 6, wherein the stacked casting dies are multiple groups, and the multiple groups of stacked casting dies are annularly arranged at the periphery of the vertical pouring gate.
8. The mold for preparing a microalloyed martensitic stainless steel cutterhead in accordance with claim 7, wherein the outer side of the tooth surface structure of the upper sand mold and the outer side of the tooth surface structure of the middle sand mold are provided with protrusions except for the inlet, and the outer side of the tooth back structure of the middle sand mold and the outer side of the tooth back structure of the lower sand mold are provided with grooves except for the inlet, and the protrusions are aligned with the corresponding grooves to form pouring cavities.
9. The die for preparing the microalloyed high-toughness martensitic stainless steel cutter head according to claim 8, wherein hemispherical positioning holes are arranged at the corresponding positions of the bulges and the bulges, and the hemispherical positioning holes are aligned to form positioning holes for accommodating positioning balls.

Description

Microalloyed high-toughness martensitic stainless steel cutter disc, preparation method thereof and preparation mold Technical Field The invention relates to the technical field of pulping machine cutterheads, in particular to a microalloyed high-toughness martensitic stainless steel cutterhead, a preparation method and a preparation mould thereof. Background The cutter disc is used as a key consumable part in the papermaking pulping industry, is widely applied to pulping process equipment such as a conical pulping machine, a double-disc pulping machine, a high-concentration pulping machine, a large-taper refining machine, a fluffer and the like, and is responsible for dissociating, thread rolling, thread separation and fine grinding of recycled paper products, wood chips, bamboo chips and non-wood plant fiber raw materials, and the quality of paper pulp, comprehensive energy consumption and continuity and stability of equipment operation are directly determined by the performance of the cutter disc. At present, the metal materials used for the papermaking cutterhead mainly comprise high-chromium cast iron, high-carbon high-chromium martensitic stainless steel and the like. High-chromium cast iron has high hardness and good wear resistance, but has extremely poor toughness, is extremely easy to generate brittle fracture under complex impact load, and leads to scrapping of the whole millstone and insufficient reliability. Therefore, the martensitic stainless steel with better comprehensive performance becomes a preferred matrix material of the high-end papermaking cutterhead. To ensure adequate hardness, strength and corrosion resistance, conventional martensitic stainless steels typically employ relatively high carbon and chromium contents. However, the high-carbon martensitic structure itself is inherently brittle, and there are a large number of twins and high dislocation density inside, resulting in a low impact toughness value. In order to improve toughness, the prior art generally employs methods of reducing the carbon content or increasing the tempering temperature. Both of these methods inevitably sacrifice the strength and toughness of the material. The microalloying technology provides possibility for further improving toughness on the premise of ensuring the strength of the material. These elements are capable of forming fine carbonitrides, optimizing performance by refining grains and precipitation strengthening. Therefore, development of a microalloyed high toughness martensitic stainless steel knife disc optimized for the papermaking pulping field is particularly urgent. Aiming at the existing modeling technology, such as integral die or integral numerical control machining, the method has obvious disadvantages. The molding process adopted by the integral die method is sand casting, and a metal die is manufactured first. The mould has no parting surface, the sand mould can be made into an upper box and a lower box, but the mould modules for forming the tooth shapes of the cutterheads are integrated. The integral die method is to manufacture blades with different tooth shapes, a complete die is required to be designed and manufactured for each tooth shape, and only 1-2 blades with the same tooth shape can be produced in the casting process, so that the cost is high and the period is long. And the integral die method has high die stripping difficulty, and if the cutter head has deeper and more complex tooth forms or larger demoulding inclination, the sand mould is easy to damage during the die stripping of the integral die. The integral numerical control machining method is to directly cut a blade meeting the requirement of tooth form through numerical control machining, and the method avoids the limitation of a die, but has the advantages of large material removal amount and long machining time. Therefore, the development of the die system for the cutterhead with different tooth shapes comprises a general lower die for supporting the central part of the cutterhead base body and a plurality of special tooth surface dies, wherein each tooth surface die has different tooth surface modeling contours, so that the production cost can be remarkably reduced, and the production efficiency can be improved. Disclosure of Invention The invention aims to provide a microalloyed high-toughness martensitic stainless steel cutter disc, a preparation method and a preparation mould thereof. The problems of the prior art that the cutter head has high brittleness, low impact toughness and poor tough fit in the background art are solved. In order to achieve the above purpose, the present invention provides the following technical solutions: A microalloyed high toughness martensitic stainless steel knife disc, wherein the stainless steel comprises ：C：0.3%~0.7%,Si：0.3%~1.0%,Mn：0.5%~1.5%,Cr：16%~18.5%,Ni：1%~2%,Mo：0.3%~0.8%,V：0.1%~0.35%,Nb：0.1%~0.25%,S：≤0.02%,P：≤0.02%, percent by weight of Fe as the rest element. Preferab