CN100420765C - steel for mining round link chain - Google Patents

Abstract

The steel for mining round link chains of the present invention relates to a manganese-containing alloy steel, which includes the following chemical components in mass percentages: C 0.17-0.30%, Mn 1.2-2.0%, Si 0.1-0.8%, Mo 0.1- 0.5%, Cr 0.1～0.8%, V and/or Nb 0.03～0.15%, Al 0.02～0.05%, S≤0.03%, P≤0.03%, Cu≤0.2%, and the rest is Fe. The steel for mine circular link chain of the present invention is produced by adopting the electric furnace steelmaking or converter steelmaking+LF refining+billet continuous casting+hot rolling process route that has been generally constructed by my country's steelmaking enterprises, and it is not necessary to use post-rolling annealing. The organization and quality are under stable control, the production process is simplified, and the cost of steel production is significantly reduced. The steel of the invention has good production process performance of the circular link chain and high hardenability, so it can be used to manufacture the circular link chain with a diameter of more than 18 mm, and has outstanding technical and economical rationality.

Description

steel for mining round link chain

technical field

The technical solution of the invention relates to a manganese-containing alloy steel.

technical background

Mining high-strength round link chain is an important part of coal mining machinery and transportation machinery. It is a vulnerable part and consumes a lot. According to national standards, circular link chains are divided into three grades: B, C and D according to mechanical performance requirements. At present, C-grade circular link chains are widely used, and 25MnV and 23MnCrNiMo54 alloy steels are widely used for manufacturing. However, 25MnV is only suitable for the manufacture of small-sized (≤φ18mm) C-grade circular link chains (medium-frequency induction heating and quenching of high-strength circular link chains for 25MnV steel mines, metal heat treatment, 11, 2004; talk about high-strength C-grade circular link chains for mining Experience of manufacturing steel, Zhongzhou Coal, 5, 1997). Adopt 23SiMnV to carry out the manufacture of C grade round link chain, although there are reports (Si influences the toughness of 20SiMnV steel used in mining round link chain, mechanical engineering materials, 4, 1986; 23SiMnV steel for mine high strength round link chain , Mechanical Engineering Materials, 3, 1985), but it is rarely used in actual production, and its specifications are limited below φ18mm. It is reported in the literature that the steel 25SiMnMoV recommended in the national standard for circular link chains for mines is used in the manufacture of grade D circular link chains (Research on the performance of high-strength circular link chains for mines with 25SiMnMoV steel, Metal Heat Treatment, 10, 1988) , but the specifications are also limited to φ18mm, and in actual production because of its Si content as high as 0.8% to 1.1%, which affects the flash butt welding performance of steel, it has not been applied. "Special Steel" No. 5 in 1986 reported a new steel type for 24SiMnNiMo circular link chains, but it was used for the production of D-grade circular link chains, and the specifications were limited to less than 18mm in diameter, and annealing treatment was required after rolling. In actual production, 23MnCrNiMo54 steel is widely used in large-size C-level circular link chains with a diameter ≥ φ22mm. This steel type is a foreign brand with high alloy costs and complicated production processes. It relies on foreign imports. Although the quality is high, the price is extremely expensive. In recent years, it has been reported in the literature that this brand of steel has been produced in China (Medium temperature tempering transformation of coal machine chain steel, metal heat treatment, 10, 2001). Due to its complex production process and other reasons, the domestic 23MnCrNiMo54 steel often has internal quality problems such as microstructure inhomogeneity and inconsistency, and its quality cannot reach the foreign level, which reduces the production efficiency of the round link chain, and the price of the steel is relatively high. Therefore, there is currently no suitable steel type in China to produce large-scale C-class round link chains. CN 85103476 discloses steel for grade D round link chains, the invention is characterized in that it consists of: weight percentage (%) C, Si, Mn, NiO.21～0.27, 0.65～0.95, 1.10～1.40, 0.80～1.10 Mo , Al, S P, Cr, Cu 0.10～0.20, 0.02～0.05, ≤0.035≤0.35≤0.25, which contains more precious elements Ni, which must be annealed after rolling to meet the requirements of shearing and blanking, so steel production The cost is high, and it is only used in the manufacture of D-level round link chains. The composition of the alloy steel reported by SU1404549 is C 0.05-0.14, Mn2.0-2.5, Cr 2.0-2.6, Si 0.15-0.4, Ni 0.2-0.4, Mo 0.20-0.30, and Al and N are added for microalloying. The content of alloying elements is high, the production cost is high, and the carbon content is low, so the wear resistance is not good. CN 00109053.4 discloses high-strength, high-toughness, corrosion-resistant steel for mooring chains and its production process. The steel contains (weight%) C: 0.25%-0.33%, Si: 0.15%-0.30%, Mn: 1.45 %-1.75%, Cr: 0.90%-1.40%, Ni: 1.00%-1.20%, Mo: 0.45%-0.65%, Nb: 0.02%-0.06%, Al: 0.020%-0.05%, residual and harmful elements P : ≤0.020%, S: ≤0.015%, Cu: ≤0.20%, Sn: ≤0,03%, Sb: ≤0.01%, As: ≤0.04%, B: ≤0.005%, [N]: ≤0.009% , [0]: ≤0.0020%, [H]: ≤0.0002%, the rest is Fe; CN 98110160.7 discloses the production method of high-strength and high-toughness mooring chain steel and mooring chain, the steel grade is 25CrMn2Mo, used for manufacturing R Grade 4 marine mooring chain; CN 99116494.6 discloses a steel for grade 4 mooring chain, the chemical composition weight percentage of the steel is carbon 0.25-0.30, silicon 0.15-0.37, manganese 0.90-1.70, chromium 0.90-1.70, Molybdenum 0.40-0.60, aluminum 0.01-0.06, nickel 0.00-0.20, copper 0.00-0.25, phosphorus 0.000-0.025, sulfur 0.000-0.025, niobium 0.02-0.04, the balance is iron; RU 2101381 and the alloy steel disclosed in EP20040002612 Contains Mn, Cr, Ni, Mo main elements. In the alloy steel disclosed in the above-mentioned patent documents, Ni and Mo contents are relatively high, which are equivalent to 23MncrNiMo54 steel, and the production cost is relatively high. The above-mentioned CN 00109053.4 CN98110160.7, CN 98110160.7 and CN 99116494.6 are all steels for high-strength mooring chains. If they are used to produce circular link chains for mines, they also have high content of alloying elements Mn, Cr, Ni and Mo, which can lead to hardening. High hardness, high hardness of steel after rolling, can not meet the requirements of circular chain shear cutting, need to be annealed, high alloy cost and the increase of annealing process lead to the shortcomings of steel production cost significantly increased. At the same time, there is no continuous annealing process after rolling in many iron and steel enterprises in my country, the cost of off-line annealing is higher, and the quality is not easy to guarantee.

Contents of the invention

The technical problem to be solved by the present invention is to provide a kind of steel for mining circular link chain, which has high hardenability and good flash butt welding performance, and the production process is simplified, so that the production cost is significantly reduced, and it overcomes the The existing steels 25MnV and 23SiMnV for C-level round link chains have insufficient hardenability in the production process of large-scale C-level round-link chains, and it is difficult to meet the mechanical properties specified in the standard. The high Si content of 25SiMnMoV steel affects the flash butt welding of steel Performance, 23MnNiCrMo54 steel Due to the high content of expensive alloy elements and complex production process, the production cost of the steel is very high, and the quality of the steel in production is difficult to be stably controlled, so that the quality cannot reach the foreign level, which reduces the production efficiency of the round link chain. shortcoming.

The technical scheme adopted by the present invention to solve the technical problem is: the mass percentages of the chemical composition of the present invention's steel for mining round link chains are: C 0.17～0.30%, Mn 1.2～2.0%, Si 0.1～0.8%, Mo 0.1-0.5%, Cr 0.1-0.8%, V and/or Nb 0.03-0.15%, Al 0.02-0.05%, S≤0.03%, P≤0.03%, Cu≤0.2%, and the rest is Fe.

The effect of the present invention's various chemical constituents of steel for mining round link chain and the reason of limiting consumption are as follows:

Carbon is an important element in the manufacture of steel for large-scale C-grade round link chains. It plays an important role in the plasticity and toughness of the steel matrix and the welding strength and toughness of the butt weld. Studies have shown that in the case of high manganese content, when the matrix structure is bainite or martensite, the carbon content exceeds 0.3%, which will greatly reduce the plasticity of the steel, especially the reduction of area and impact value; The wear resistance requirements of mining circular link chain products, the carbon content is 0.17% as the lower limit.

Manganese is the main alloying element added in the steel for mining round link chains of the present invention. It is added in conjunction with a small amount of molybdenum, which can significantly affect the microstructure transformation kinetics of the steel, play a role in inhibiting the diffusion-type phase transition, and significantly improve the strength of the steel. Hardenability. At the same time, it dissolves in ferrite and plays a role of solid solution strengthening. Considering the mechanical properties of the circular link chain, the requirements of the process properties and the process route of steel production, the manganese content is determined to be 1.2% to 2.0%.

The long-term production practice of circular link chains shows that the addition of alloying element molybdenum can improve the flash butt welding performance of steel, especially the ability to resist overheating during butt welding. At the same time, the combined effect of molybdenum and manganese can significantly improve the stability of austenite and the hardenability of steel, so as to ensure that the mechanical properties of large-scale circular link chains meet the standard requirements. The addition of too much molybdenum will significantly increase the cost of steel, and the effect will no longer be significantly improved, so the content of molybdenum is determined to be 0.1% to 0.5%.

The addition of elemental silicon is mainly to improve the tempering resistance of the steel and the yield strength of the steel so that the test elongation of the finished circular link chain meets the requirements of the national standard. Considering that the increase of silicon content will increase the resistance of the material, the arc current of the material will increase during flash butt welding, resulting in high temperature and overheating of the material. Serious damage to welds. Therefore, in the steel for mining round link chains of the present invention, unlike the steel types developed in the past, the content of silicon is limited, and it is only added as an additional element, and the amount of silicon added is less than 0.8%.

The addition of chromium is mainly to be suitable for the production of large-scale round link chains, to ensure its hardenability, and thus to have good mechanical properties. Considering the interaction of added elements, the maximum amount of chromium added is not more than 0.8%.

In order to make the steel raw material for the round link chain have a uniform and fine structure, the steel for the mine round link chain of the present invention adopts vanadium and/or niobium microalloying, and simultaneously improves the structure of the flash butt welding seam and the heat-affected zone, and also has It helps to inhibit the grain growth during quenching and heating, so that the steel has good plasticity and toughness.

Aluminum is only an element remaining after deoxidation during the smelting of steel.

Sulfur, phosphorus and copper are all impurity elements, the less the content, the better.

The preparation method of the steel for mining circular chain of the present invention is: according to the chemical composition composition batching of the steel for mining circular link chain of the present invention, through converter steelmaking or electric furnace steelmaking, LF refining, that is, ladle refining, billet continuous Casting and hot-rolling process routes are produced, and these process steps are all known in the field of metallurgical technology.

The steel used for mining circular link chains of the present invention is used for the production process route of circular link chains: shearing blanking, hot knitting, sandblasting, flash butt welding, pre-stretching, quenching and tempering heat treatment and secondary pre-stretching, these The process steps are also well known in the art of circular link chain manufacture.

The steel for mining circular link chains of the invention is used to prepare high-strength circular link chains for coal mining machinery and transportation machinery.

The beneficial effects of the present invention are: the steel for mining circular link chains of the present invention is a low-cost new circular link developed based on the theory of diffusion phase transformation and martensitic phase transformation, utilizing the interaction of alloying elements in steel Low-carbon multi-element low-alloy steel for chains is used to replace the expensive 23MnNiCrMo54 steel to manufacture large-scale C-grade high-strength mining circular link chains with a diameter ≥ φ22mm, thereby achieving significant economic benefits. Compared with the existing steel for C-grade round link chains, the invention has higher cost performance through optimal alloying composition design.

1. Compared with 25MnV and 23MnSiV steels, the steel for mining circular link chains of the present invention has higher hardenability, so it can be used to manufacture circular link chains with a diameter of more than 18mm, which overcomes the existing production of large-scale C-level circular rings Chain steels 25MnV and 23MnSiV have insufficient hardenability in the production process of round link chains, which makes it difficult to meet the mechanical properties stipulated in the standard.

2. According to the service performance requirements and production process requirements of high-strength C-level circular link chains, and in combination with the existing production process routes and equipment levels of converter or electric furnace steelmaking + LF refining + continuous casting + hot rolling, the mining chain of the present invention The design of the steel for the round link chain is based on the use of low carbon martensite as the structure of the round link chain product, using the best multi-alloying effect of Mn, Mo, Cr, Si, after quenching and tempering, to meet the circular At the same time, under hot rolling conditions, non-martensitic structure can be obtained, eliminating the post-rolling annealing process of 23MnCrNiMo54 steel, with uniform structure and low hardness, which is conducive to the development of ring chain Shear blanking, in the case of large-scale thermal knitting, can achieve uniform weld seam gap, and has good flash butt welding performance.

3. Under the premise of ensuring the mechanical properties and process performance of the deep-processed product circular link chain, the steel for the mine circular link chain of the present invention saves the precious alloying element Ni and reduces the content of the alloying element Mo, compared with the 23MnNiCrMo54 steel. The electric furnace steelmaking or converter steelmaking + LF refining + billet continuous casting + hot rolling process route that has been generally established by my country's steelmaking enterprises is used for production, without post-rolling annealing, the steel production process is simplified, and the production cost is significantly reduced. At the same time, it also avoids the problem of uneven structure and hardness caused by the annealing of 23MnNiCrMo54 steel after rolling, which affects welding. The organization and quality of the steel are under stable control, and have good production process performance of the circular link chain. The mechanical properties of the circular link chain manufactured by the steel for mining circular link chain of the present invention are better than the requirements of GB/T12718-2001, which will greatly improve the economic benefits of my country's iron and steel production enterprises and coal mining machinery factories.

Detailed ways

Example 1

The mass percentages of the chemical composition of steel ingredients for mine round link chains are: C 0.17%, Mn 2.0%, Si 0.1%, Mo 0.5%, Cr 0.1%, V 0.11%, Nb 0.03%, Al 0.02%, S 0.03%, Cu 0.08%, and the rest is Fe; the ingredients are smelted in electric furnace, LF refining, 150 billet continuous casting, and hot rolling into φ22mm high-strength mining circular chain steel for coal mining machinery and transportation machinery ; and then through shearing, hot knitting, sandblasting, flash butt welding, pre-stretching, tempering heat treatment, and secondary pre-stretching to obtain a finished 22×86 round link chain.

The bending performance of the circular link chain: under the conditions of quenching at 880°C and tempering at 420°C/1.5 hours, the bending is qualified according to GB/T12718-91; tensile mechanical properties: breaking load 750KN, elongation at break 15%, test Elongation 1.4%; Fatigue performance: more than 30,000 times.

Example 2

The mass percentages of the chemical composition of steel ingredients for mining round link chains are: C 0.17%, Mn 2.0%, Si 0.1%, Mo 0.5%, Cr 0.1%, V 0.15%, Al 0.02%, P 0.01%, S 0.03%, Cu 0.08%, all the other are Fe; Others are with embodiment 1.

Example 3

The mass percentages of the chemical composition of steel ingredients for mining round link chains are: C 0.17%, Mn 2.0%, Si 0.1%, Mo 0.5%, Cr 0.1%, Nb 0.15%, Al 0.02%, P 0.01%, S 0.03%, Cu 0.08%, all the other are Fe; Others are with embodiment 1.

Example 4

The mass percentages of the chemical composition of steel ingredients for mine round link chains are: C 0.23%, Mn 1.5%, Si 0.4%, Mo 0.3%, Cr 0.4%, V 0.09%, Nb 0.03%, Al 0.03%, S 0.01%, P 0.02%, Cu 0.13%, and the rest is Fe; the ingredients are smelted by converter, LF refining, 150 billet continuous casting, and hot rolled into high-strength mining rounds of φ26mm for coal mining machinery and transportation machinery. Steel for link chains; 26×92 round link chain finished products are made by shearing, hot knitting, sandblasting, flash butt welding, pre-stretching, quenching and tempering heat treatment, and secondary pre-stretching.

The bending performance of the circular link chain: under the conditions of quenching at 880°C and tempering at 420°C/1.5 hours, the bending is qualified according to GB/T12718-91; tensile mechanical properties: breaking load 930KN, elongation at break 14%; test Elongation 1.4%; Fatigue performance: more than 30,000 times.

Example 5

The mass percentages of the chemical composition of steel ingredients for mine round link chains are: C 0.23%, Mn 1.5%, Si 0.4%, Mo 0.3%, Cr 0.4%, Nb 0.09%, Al 0.03%, S 0.02%, P 0.01%, Cu 0.13%, all the other are Fe; Others are with embodiment 4.

Example 6

The mass percentages of the chemical composition of steel ingredients for mine round link chains are: C 0.23%, Mn 1.5%, Si 0.4%, Mo 0.3%, Cr 0.4%, V 0.09%, Al 0.03%, S 0.01%, P 0.01%, Cu 0.13%, all the other are Fe; Others are with embodiment 4.

Example 7

The mass percentages of the chemical composition of steel ingredients for mining round link chains are: C 0.30%, Mn 1.2%, Si 0.8%, Mo 0.1%, Cr 0.8%, V 0.03%, Nb 0.08%, Al 0.05%, P 0.03%, Cu 0.2%, and the rest is Fe; the ingredients are smelted by converter, LF refining, 150 billet continuous casting, and hot rolled into φ30mm high-strength mining circular chain steel for coal mining machinery and transportation machinery; After shearing and blanking, hot knitting, sandblasting, flash butt welding, pre-stretching, quenching and tempering heat treatment, and secondary pre-stretching, the finished product of 30×126 round link chains is obtained.

The bending performance of the circular link chain: under the conditions of quenching at 880°C and tempering at 420°C/1.5 hours, the bending is qualified according to GB/T12718-91; tensile mechanical properties: breaking load 1220KN, elongation at break 14.5%; test Elongation 1.1%; Fatigue performance: more than 30,000 times.

Example 8

The mass percentages of the chemical composition of steel ingredients for mining round link chains are: C 0.30%, Mn 1.2%, Si 0.8%, Mo 0.1%, Cr 0.8%, V 0.03%, Al 0.05%, S 0.01%, P 0.03%, Cu 0.2%, all the other are Fe; Others are with embodiment 7.

Example 9

The mass percentages of the chemical composition of steel ingredients for mine round link chains are: C 0.30%, Mn 1.2%, Si 0.8%, Mo 0.1%, Cr 0.8%, Nb 0.03%, Al 0.05%, S 0.03%, P 0.01%, Cu 0.2%, all the other are Fe; Others are with embodiment 7.

Examples 10-17

According to the mass percentage of the chemical composition of steel for mining round link chains listed in Table 1, use Nb and V composite microalloying, V or/and Nb 0.03 ~ 0.15%, the rest is Fe ingredients, and the ingredients are passed through the electric furnace Smelting, LF refining, continuous casting of 150 billet, hot rolling to diameters listed in Table 1 for high strength mining circular link chain steel for coal mining machinery and transportation machinery.

Table 2 lists the mechanical properties of the steel for mining circular link chains of the present invention with different specifications in Table 1.

Table 3 lists different specifications in table 1. Steel for mining circular chains of the present invention is cut and blanked, hot-knitting, sandblasting, flash butt welding, pre-stretching, intermediate frequency induction quenching and tempering heat treatment, and secondary pre-stretching The mechanical properties of the finished round link chain produced by the process route trial production. The determination of mechanical properties is carried out according to GB/T12718-2001, and the results fully meet the requirements of GB/T12718-2001.

Table 1 The chemical composition of steel for mining round link chains (mass%)

chain number Specification C Si Mn Cr Mo Al P S Cu 10 L201 Φ22 0.22 0.56 1.55 0.20 0.30 0.025 0.02 0.015 0.08 11 L202 Φ22 0.23 0.66 1.35 0.20 0.40 0.03 0.008 0.025 0.10 12 L203 Φ22 0.18 0.25 1.67 0.25 0.35 0.027 0.015 0.020 0.11 13 L204 Φ26 0.24 0.72 1.20 0.55 0.32 0.025 0.02 0.025 0.08 14 L205 Φ26 0.24 0.63 1.25 0.62 0.35 0.022 0.018 0.020 0.09 15 L206 Φ26 0.25 0.58 1.30 0.58 0.33 0.023 0.009 0.025 0.10 16 L207 Φ30 0.24 0.42 1.35 0.66 0.43 0.025 0.013 0.026 0.08 17 L208 Φ30 0.26 0.38 1.66 0.45 0.28 0.028 0.016 0.022 0.13

Table 2 Mechanical properties of steel for mine circular link chains

Table 3 Mechanical properties of mining circular link chains

chain number Specification  Test elongation, % Breaking load, KN Elongation at break, % Weld impact toughness, J Fatigue performance Bending properties L201 Φ22 1.40 750 15 88 55000 qualified L202 Φ22 1.22 755 18 92 42000 qualified L203 Φ22 1.44 740 16 86 41000 qualified L204 Φ26 1.16 950 14 82 38000 qualified L205 Φ26 1.36 960 15 88 48000 qualified L206 Φ26 1.26 930 16 82 38000 qualified L207 Φ30 1.40 1260 16 88 37000 qualified L208 Φ30 1.42 1240 15 84 40000 qualified

Claims (1)

1. ring chain steel for mine is characterized in that: the mass percent that the chemical ingredients that this ring chain steel for mine comprises is formed is: C 0.18～0.25%, Mn 1.2～1.67%, Si 0.25～0.72%, Mo 0.3～0.43%, Cr 0.2～0.66%, V and/or Nb 0.03～0.15%, Al 0.022～0.03%, S≤0.03%, P≤0.03%, Cu≤0.2%, all the other are Fe.