Method for preparing medium and low carbon manganese iron nitride by microwave sintering

Abstract

The invention discloses a method for preparing medium and low carbon manganese iron nitride by microwave sintering. The method comprises the steps of weighing medium and low carbon manganese iron powder with granularity of 40-60 meshes per inch and accounting for 25% and medium and low carbon manganese iron powder with granularity of 60-80 meshes per inch and accounting for 75%, adding an adhesive which accounts for 8-10% of the mass of the medium and low carbon manganese iron powder, mixing uniformly, under the pressure of 50-60 kilograms, pressing the mixture to a material blank, drying until that the water content is no more than 3% by weight, then placing the mixture to a microwave oven, heating until the temperature is in a range of 350 DEG C to 400 DEG C, feeding nitrogen into the microwave oven, raising the temperature continuously to the range between 880 DEG C and 1000 DEG C at a temperature rising speed of 5-10 DEG C / minute, performing heat preservation, cooling the mixture along with the furnace to the range between 400 DEG C and 500 DEG C, discharging the mixture, and performing air cooling to obtain the medium and low carbon manganese iron nitride. The method is reasonable in process, convenient to operate, short in production period and low in energy consumption. The prepared medium and low carbon manganese iron nitride is high in nitrogen content, the nitrogen is distributed uniformly in the base metal, and the method is suitable for industrial application.

Description

technical field [0001] The invention discloses a method for preparing medium and low carbon ferromanganese nitride by microwave sintering, which belongs to the technical field of ferroalloy preparation. Background technique [0002] Ferromanganese nitride is an essential alloying agent for the production of special alloy steel, stainless steel, and automotive, shipbuilding, and aviation industry materials. It can improve the strength and plasticity of steel. Nitrogen is an element that expands the austenite zone. Therefore, manganese and nitrogen can replace nickel in many steel grades in stainless steel, and nickel is a rare and precious metal, such as CrMnN stainless steel containing N0 .5%-0.6%, oil and gas pipeline steel contains N0.05%-0.1%. [0003] The traditional production method of ferromanganese nitride is: use solid powdery medium-low carbon ferromanganese to heat in a closed vacuum resistance furnace and then fill it with nitrogen gas, so that the powdery mediu...

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Problems solved by technology

[0008] 1. The power consumption is high, and the power consumption per ton of products is above 2300KW. In addition, due to the rapid rise of electricity prices in my country, the proportion of the production cost of the products is getting higher and higher, and the products have no production profits;

[0009] 2. Since the particle size of the raw material is controlled below 80 mesh, the porosity of the raw material after pelletizing is low (less than 20%), and the infiltration rate and amount of nitrogen gas are restricted;

[0010] 3. Nitrogen products have low nitrogen content and large composition segregation: Due to the defects of the heating method of traditional equipment, there is a large temperature gradient from the surface to the center of the medium and low carbon ferromanganese briquettes in the furnace. When the temperature in the furnace is 1000- At 1100°C, the surface of the medium and low carbon ferromanganese briquette begins to appear in a partial melting state, but the temperature of the core is lower than the optimum nitriding temperature. On the one hand, the surface nitrogen content of the product is higher; on the other hand, the medium and low carbon The partial molten state on the surface of the ferromanganese briquette prevents nitrogen from fully penetrating into the briquette, resulting in low nitrogen content inside the product; The nitriding speed of Nitrogen has decreased significantly, and the output is very low. It is produced by traditional methods. The nitrogen content of the product is: 3-5%, and the composition segregation is large.

[0011] 4. Low output: Due to the process and equipment, the traditional production method takes a long time for nitriding during production. An electric furnace with a power of 1500KW has a daily output of 800Kg. The output is low, the production efficiency cannot be effectively utilized, and the product is difficult to meet market demand.