42results about How to "Shorten carburizing time" patented technology

The invention relates to Nb and Ti composite micro-alloyed high-temperature carburized gear steel, and belongs to the technical field of alloy steel. The gear steel comprises the chemical components of, by mass: 0.17-0.22% of C, 0.20-0.35% of Si, 0.9-1.10% of Mn, 1.05-1.30% of Cr, 0.02-0.06% of Ti, 0.02-0.06% of Nb, 0.015-0.035% of Al, no more than 0.025% of P, 0.020-0.035% of S, and balance of Fe and inevitable impurities. The steel has the advantages that: through controlling the contents of Nb and Ti alloy elements, the carburization temperature of a current gear can be improved, gear carburization time can be reduced, and gear production cost can be reduced.

The invention discloses high-temperature vacuum carburized gear steel. The high-temperature vacuum carburized gear steel comprises: by weight, 0.10 to 0.30% of C, 0.15 to 0.25% of Si, 0.60 to 0.90% of Mn, less than or equal to 0.025% of P, 0.010 to 0.020% of S, 0.85 to 1.25% of Cr, 0.033 to 0.055% of Al, 0.0160 to 0.0300% of N, 0.001 to 0.009% of Ti, less than or equal to 0.0020% of O and the balance Fe and unavoidable impurities. Through a micro-alloying method, abnormal growth of austenite grains of gear steel in high-temperature vacuum carburizing is controlled and thus steel grain granularity is strictly controlled in a range of 7.0 to 8.0 grade and hardenability (J5mm) is stably controlled in a range of 32 to 42 HRC so that various performance requirements of common gear steel are satisfied. The high-temperature vacuum carburized gear steel contains simple alloy elements, has a low cost, allows stable and reliable process control, can be utilized for high-temperature vacuum carburizing, greatly reduces carburizing time, is environmentally friendly and saves energy.

The hard alloy carburizing process resulting in gradient distributioin of mechanical performance includes the steps of preparing carburizing agent, loading into boat and carburizing treatment. The carburizing agent consists of Al2O3, graphite grain, and carbonate and / or bicarbonate in certain proportion and mixed together. During the carburizing treatment, carbonate and / or bicarbonate are decomposed into CO2, CO2 is then reacted with graphite to produce relatively active CO, and CO enters to liquid phase and reacts with eta phase to produce WC while immigrating inwards and to speed the formation of gradient structure inside the alloy. The present invention has the features of relatively low carburizing temperature, high comprehensive mechanical strength formed, short carburizing time, etc.

The invention discloses a heavy-duty gear carburizing and quenching method, and relates to the technical field of special steel making. The method comprises the following steps that a gear workpiece is subjected to carburizing treatment in a gas carburizing furnace, and then is subjected to austenitizing heating thermal insulation after getting out of furnace; then the gear workpiece is subjectedto precooling quenching; the gear workpiece is subjected to water-base medium quenching, salt bath quenching and fog cooling in sequence; and the gear workpiece is washed after fog cooling is finished, and then is subjected to tempering treatment. With the heavy-duty gear carburizing and quenching method, the problem that for a large-control-section gear made of a low-hardenability material, a quenching method in the prior art cannot achieve the purposes of making the performance of a center part and a gear root excellent and having effectively control over stress type cracking at the same time is solved, it is achieved that a heavy-duty gear is controllable in carburizing and quenching deformation without cracks, and the hardness, the texture, a hardened layer and the dynamic performanceof the heavy-duty gear all meet the technological design requirements.

In a first process of a method of gas carburizing, a steel treatment object in a carburizing atmosphere containing carburizing gas is heated to an initial set temperature which is not higher than a peritectic point at which δ iron and a liquid phase transform into γ iron and not less than a eutectic point at which the liquid phase transforms into γ iron and cementite, such that the surface carbon concentration thereof does not exceed a solid solubility limit. In a second process following the first process, the carburizing temperature is gradually decreased from the initial set temperature such that the surface carbon concentration of the treatment object increases without exceeding the solid solubility limit, and such that the carburized depth of the treatment object increases.

The invention discloses a method for realizing nitriding or carburizing by thermal airflow jetting heating and shot blasting. Crystal defects on the surface of manufactured metal can be controlled, and surfaces of components are precisely heated at high speed. The method comprises the following steps of: (1) installing the cleaned components in a chemical thermal treatment furnace, keeping the spacing distance of 15-100mm between the surfaces of the components needing nitriding or carburizing, and abutting the surfaces not needing nitriding or carburizing so as to save the space; (2) nitriding or carburizing: heating a nitriding agent to 300-500 DEG C or a carburizing agent to 650-800 DEG C by using a thermal airflow generator, jetting to the surfaces of the components through a thermal airflow nozzle so as to heat surface layers of the components at high speed; at the same time, jetting balls to the surfaces of the components by using a shot blasting machine so as to manufacture the crystal defects on the surface layers of the manufactured metal simultaneously with increasing the surface temperature of the components, wherein the nitriding time is 0.5-6 hours, and the carburizing time is 0.5-4 hours; and (3) cooling after nitriding or carburizing.

The invention discloses a method for quickly preparing gradient cemented carbide by adding rare-earth elements, and belongs to the field of manufacturing cemented carbide materials. The method disclosed by the invention comprises the following steps: pressing and forming carbon-poor cemented carbide powder containing rare earth, and performing vacuum sintering to obtain a carbon-poor presintering base body; performing carburizing treatment for 40-120 minutes at the temperature of 1,400-1,460 DEG C under the hydrogen atmosphere to obtain the gradient cemented carbide, wherein the thickness of a gradient layer of the gradient cemented carbide is 200-3000 [mu]m. The rare-earth elements are added in the process of preparing the gradient cemented carbide, so that alloying components are solidified and dissolved in a Co phase in the presintering process, and the effect of inhibiting crystal grains from growing can be achieved. But in the carburizing process, the influence of adding the rare earth on the dissolution and the separation of WC (wolfram carbide) in the Co phase is weakened, and more passages are provided for the diffusion of activated carbon, so that the thickness of the gradient layer of the alloy can be quickly increased.

The invention discloses a graphite source electrode for glow carburizing without hydrogen. The graphite source electrode comprises an external graphite cover body and an internal graphite cover body which are arranged in parallel, the internal and external graphite cover bodies are cube-shaped generally, the same sides of the external graphite cover body and the internal graphite cover body are provided with a temperature-measuring ventilation hole respectively; needle-like graphite source electrodes are uniformly distributed at the upper and lower parts of the internal graphite cover body, and a graphite clamp for clamping a workpiece is provided in the internal graphite cover body and suspends the workpiece horizontally between needle-like graphite source electrodes which are evenly distributed at the upper and lower parts; metallic cover body is arranged outside the external graphite cover body and one side of the metallic cover body is provided with a temperature-measuring ventilation hole. When a pure-titanium workpiece is subjected to glow carburizing without hydrogen by means of the graphite source electrode disclosed by the invention, the sputtering rate of carbon can be increased by more than 26 times, and the carburizing layer is uniform and dense, the carburizing time is effectively shortened, the carburizing temperature is reduced and the carburizing efficiency is increased.