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Fastener Toughness And Plasticity
Nov 03, 2017

Self-tapping screws in threaded fasteners, self-tapping locking screws not only require high strength, wear resistance, but also requires the Ministry of the heart has sufficient toughness and plasticity,Fastener whether low carbon steel or carbon, carbon steel Manufacturing, are required by carburizing or carbonitriding quenching, in order to achieve the design and use needs.

Carburizing refers to the process of infiltrating carbon atoms into the surface layer of steel so that the chemical composition of the surface of the steel is close to that of high-carbon steel, so that the low-carbon steel has the hardness, abrasion resistance and fatigue strength of the high-carbon steel. Fastener The carburizing material is generally carbon Steel or low carbon low alloy steel.

The traditional gas carburizing technology, the carburizing process is generally divided into decomposition, adsorption and diffusion of three stages. The current use of fasteners is more with the furnace with furnace carburizing, the carbon potential of the device is mainly through the rear of the furnace body oxygen probe to measure and control the entire furnace carbon potential distribution, the technical shortcomings are In the carburizing process, the workpiece is always in a high-carbon potential state and it is difficult to obtain a good graded distribution of carbon concentration in the layer.

The test non-muffle SY-805-6 three permanent nets with furnace, the furnace, heating elements, thermocouple, oxygen probe, mixing fan and conveyor belt, Fastener the furnace by the impermeable layer, insulation layer and furnace shell composition, Furnace through structure, using the exhaust before the way. Parameters such as time, carbon potential and temperature can be set and executed in the PLC system program. Process programs can be displayed on the computer screen, and has fault self-diagnostic function. The time is controlled by the frequency converter, the carbon potential is controlled by a carbon controller, the signal is measured by a responsive oxygen probe, Fastener the power is controlled by a three-phase SCR power regulator, and the temperature signal is measured by a thermocouple; the carburizing agent is propane and methanol, For the diluent, the flow rate is 1800 ~ 2400CC / h, propane is rich gas, the flow rate is controlled by the solenoid valve according to carbon potential.

Furnace temperature stabilized at 880 ℃, setting carbon potential of 1.2%. The Sanyong SY-805-6 Belt Furnace is divided into 6 zones. The oxygen probes are installed in zones 4 and 5. The carbon potential of zones 4, 5 and 6 is measured with a three-gas analyzer, with 1.18% in zone 4 and 5 Zone 1.21%, Zone 6 1.24%. Fastener The uniformity of the atmosphere in the belt furnace is controlled by the stirring fan. The products are still in the heating stage in the front of zone 3. The temperature is low and the carburizing effect is poor. The oxygen probe is not installed. The carbon potential in the front of the furnace mouth is low. Fastener The decomposition of carbon potential increased slightly.

No matter what kind of carburizing method is adopted, the carburizing agent used after carburizing agent cracking by high temperature should be CO, CO2, CH4 and H2, Fastener and produce active carbon atoms to adsorb and diffuse on the surface of the workpiece to form carburized layer with certain carbon concentration .

Carburizing screws are shallow carburizing, Fastener the use of mesh belt carburizing furnace is very favorable, the workpiece is processed in accordance with pre-set conditions, the workpiece in a continuous loading furnace mouth, after treatment in the continuous discharge of the discharge port. As the carburization time increases, the factors influencing the carburization rate also change. That is, Fastener the increase of the depth of the carburizing layer is mainly controlled by the diffusion speed of carbon in the steel.

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