Development of modified high manganese steel plate hammer and hammer head

Test bird research on the development of modified high manganese steel plate hammer and hammer head Zhai Kezhanfu Gaojie Wang Guoxuehe 1 * Bamboo UHW Cement Plant (452370) F. Suhong Pan Yi-Huanluo mil 丨 Zhi Gong According to the requirements of limestone input particle size, physical properties and product fineness, the first-level crushing of limestone in the enterprise is generally the impact type and hammer crusher. Plate hammer and hammer head are one of the key components of these crushers. The quality of the crusher has always been a concern of cement manufacturers. Its safety, reliability, wear resistance and service life directly affect the safe production cycle and production cost of the cement plant, as well as the labor intensity of the workers. Therefore, the cement plant attaches great importance to the safety of the crusher hammer and hammer head Running quality.

Similarly, our factory has always attached great importance to the quality of the hammer and hammer head of the crusher. For the * 1250x1250 double rotor impact crusher hammer and PC16x16 hammer crusher hammer head required by our factory, we have tried and studied The high manganese steel products of different manufacturers are not very satisfactory, and some of them have broken blocks; some of the work surfaces have serious furrows and rheology, are not wear-resistant, and have a short service life, and most are used for three months. The use of one month at least brings a lot of difficulties to the normal production of our factory, and even damages the equipment and causes significant economic losses. Therefore, the hammers and hammer heads of the crusher have attracted our great attention. After in-depth and detailed investigation, research and comprehensive demonstration, we have cooperated with Luoyang Zhili Industrial Co., Ltd. to jointly develop a modified high-manganese steel hammer and hammer head. The head can effectively avoid the above problems, and the service life and wear resistance are more than doubled compared with the ordinary high-strength steel products used in the past.

I High manganese steel hammer and hammer head The cast structure of the high manganese steel hammer and hammer head is austenite and carbide. After water toughening, it is a single austenite structure with high toughness. Under impact conditions, it can produce work hardening ability, which has better wear resistance. However, due to the low hardness of limestone, the hammer and head of the crusher cannot produce sufficient work hardening under low and medium impact stress. So that the working surface hardness of the hammer and the hammer head is not high enough, and the wear is faster; in addition, the high manganese steel hammer and the hammer head are below 3 (rc, and the carbide re-precipitation will occur around the grain boundary of the internal structure. Yes, a relatively complete and dense substrate is cut by carbide. Because the hardness of the substrate is lower than that of the carbide, the substrate wears first, so that the carbide protrudes, and the protruded carbide is scratched, broken, or peeled off, losing the substrate. The protection of the substrate is further abraded, so the cycle is repeated, so that the high manganese steel plate hammer and hammer head are not wear-resistant, and the service life is short.

The chemical composition of the two modified high manganese steel hammers and heads The wear resistance of high manganese steel is mainly due to its work hardening ability. Therefore, when we design the chemical composition of the modified high manganese steel hammer and hammer head, we consciously Adding chromium (Mo), molybdenum (Mo), titanium (T, vanadium (V) and rare earth elements. Reduce the stability of austenite, make a large number of tiny second phase particles on the matrix to prevent dislocation movement, In order to strengthen the matrix, and make it disperse and precipitate spherical carbides on the austenite, purify the grain boundaries, improve the morphology and distribution of inclusions, and achieve comprehensive strengthening, so that it has high button, high strength and good anti-wear performance. The selection of modified high manganese steel plate hammer and hammer head material elements is as follows.

2.1 Carbon (Ci content selection Carbon is the dominant element in steel that affects various properties. Within a certain range, with the increase of carbon content, the hardness, breaking strength, yield strength and wear resistance of steel increase. However, when When the carbon content is greater than 1.4%, the toughness is reduced. There are coarse carbides distributed along the grain boundaries, which makes it difficult to eliminate the solid solution treatment of the carbides. Therefore, the carbon content is selected from 1.1% to 1.2%. 2.2 Manganese (Mn) content selection Manganese is one of the strongest grain boundary carbide forming elements to form stable austenite, or an overheat-sensitive element. When the content is low, it cannot meet the austenite formation conditions. Increase, the strength and wear resistance of steel also increase. However, when the manganese content is greater than 14%, various properties of the steel will no longer improve, and the formation of manganese carbides, easy to produce coarse columnar crystals, which brings heat treatment Difficulties will also increase casting shrinkage, reduce thermal conductivity, and increase the tendency of castings to crack, resulting in various casting defects. Therefore, manganese content Zhai Kezhan, etc .: Development of modified high-strength steel plate hammer head test concrete island kitchen 2.3 Silicon Selection of (Si) content Silicon has a significant solid solution strengthening effect, increasing the compactness of steel and improving wear resistance. When the silicon content is less than 0.3%, the content of manganese oxide (MnO) in steel increases, which promotes hot cracking and cannot ensure deoxidation. When the silicon content is too high, it will also reduce the solubility of carbon in F-Fe, promote the precipitation of carbides along the grain boundaries, and reduce the toughness. The silicon content is usually controlled at 2.4 chromium (Cr). The choice of chromium can significantly increase the steel Hardenability, solid solution strengthening matrix, promote the formation of ferrite, reduce the stability of austenite, improve the work hardening ability. Chromium content is generally controlled at ~ 2.5 Mo Austenite can greatly improve the hardenability, tempering stability, and grain refinement of steel; molybdenum also has the effect of controlling temper brittleness and improving impact toughness. The content of molybdenum is controlled at 0.25% 2.6 titanium (Ti ), The content of vanadium (V) and rare earth. They are mainly used as modifiers to purify grain boundaries, refine grains, and disperse and precipitate spherical carbides on the austenite matrix to achieve comprehensive strengthening. Their content is very small.

2J Selection of Phosphorus (P) Content Phosphorus is the most harmful element in steel. It forms a low-melting phosphate with iron and manganese. When the content is too high, it will form a eutectic, cracking the casting, and impact toughness and wear resistance. Both are unfavorable, and its content should be as low as possible, but considering that ferromanganese contains higher phosphorus, the phosphorus content should be controlled below 0.07%.

3 Melting, casting and heat treatment of modified high-manganese steel plate hammer and hammer head 3.1 Melting We adopt non-oxidation smelting in a 750kg alkaline furnace lining medium frequency induction furnace. The composition of the steel is calculated according to the chemical composition and absorption rate of the charge and ferroalloy. The hot furnace is charged to prevent the introduction of gas. The ferromanganese is added to the material. The maximum power is sent during melting. The steel is measured when the steel is 90% molten. The temperature of the liquid to avoid the temperature of the molten steel being too high. When the temperature of the molten steel reaches 1500 * C, take a sample and do a chemical analysis before the furnace. Then, according to the analysis result, add a ferroalloy to adjust the various metal elements required. When the molten steel temperature reaches 1550X :, tap out. Adopt the insertion method to punch the aluminum in the ladle for final deoxidation. After adding aluminum, add the conditioner to the molten steel quickly by forced placement. When the surface of the molten steel will form a film, 3.2 Casting is an important link that affects the quality of castings. The casting process, pouring process and cleaning process must be strictly implemented. We adopt the fixed 22-way solidification process, and the pouring temperature is controlled at 1. Due to the low pouring temperature, it is necessary to pay attention to the smoothness of the pouring riser system, so that the molten steel can be quickly and smoothly filled and effectively filled, to prevent cold cracks and improve casting. Primary crystalline structure, eliminate columnar crystals, create thermodynamic conditions for the formation of equiaxed crystals, reduce intergranular defects and segregation, increase the density of steel, and ensure that castings have good mechanical properties.

3.3 The heat-treated cast hammer and hammer head are relatively brittle and cannot be used in the cast state, and must undergo solution treatment (water toughening treatment). The furnace temperature of the hammer and hammer head is controlled below 40 (TC, then, as the temperature rises, trapezoidal insulation is carried out in stages. Finally, when the furnace temperature reaches 15 * C, insulation is performed for 20-24h to complete carbonization Decomposition of substances' carbon, manganese and other elements dissolve in austenite and homogenize the austenite. After the furnace temperature reaches 1KXTC, open the furnace door and quickly quench the workpiece with water.

Water quenching uses a large-volume pool, which is treated by flowing water, that is, cold water is sprayed from the bottom up with a high-pressure water system under the pool, and hot water overflows above the pool. The water temperature in the pool is strictly controlled between 20-40r. Finally, take out the workpiece for air cooling.

4. The use effect of modified high-strength steel plate hammer and hammer head The modified high-manganese steel plate hammer and hammer head, after undergoing modification treatment, refine the grains, improve the wear resistance, and at the same time ensure better toughness , Effectively prevent the problem of breaking and falling off under strong impact conditions, and can improve the work hardening ability. Taking * 1250x1250 double rotor impact crusher hammer as an example, after using modified high manganese steel hammer, there is no The problems of breakage and falling blocks reappeared, basically eliminating furrows and rheological phenomena. A pair of hammers crushed 200,000 tons of limestone, with a service life of more than one year. The performance comparison of ordinary high manganese steel hammer and modified high manganese steel hammer is shown in Table 1. From Table 1, it can be seen that Table 1 Ordinary high manganese steel 4 Sakahammer and modified performance items. The continuous service life of limestone (ten thousand tons) (months), relative wear resistance, ordinary local fierce steel modified high manganese steel is more than 500 and more than 2 to clearly see that the working surface hardness of the modified high manganese steel hammer reaches HB500. ±, its work hardening ability is higher than ordinary high manganese steel, and its wear resistance is more than twice that of ordinary high manganese steel. Therefore, the modified high manganese steel plate hammer and hammer head can effectively improve the safe operation cycle of the crusher, reduce the labor intensity of workers, and improve the economic benefits of the cement plant.