The main effect of holding time carburizing layer depth. In the condition of certainmedium capacity carburizing, nitriding depth is a function of temperature and time. At the same temperature of carburizing, carbonitriding layer temperature increased with the holding time is prolonged, the parabola relation in the early,carburizing, penetration speed, increased with time, carburizing speed slow,carbon concentration gradient in the carburized layer gradually decreased. In the actual production, often according to the average rate of carburizing heat preservation time, both to improve productivity, but also get the layer depth,surface carbon content and reasonable carbon concentration gradientpermeability given. The design of the heat preservation time carburizing is set to 8h.
According to the method of control of furnace gas, drip gas carburizing can be pided into fixed carbon potential method and subsection control method two.Considering the design of parts requirements of carburized layer depth in 1.4~1.9mm, select the segment control method. The carburizing process iscarbon, infiltration agent consumption, carbon black, the surface carbon content is appropriate, the carbon content distribution is more uniform.
Subsection control method by exhaust gas carburizing process, strongpermeability, diffusion and four stage cooling.
Exhaust gas phase methanol amount is 13.65mL/min, do not join the kerosene.
In the carburizing carburizing stage, the temperature has risen to 900 ℃, kerosenehas been able to fully decomposed, to increase the amount of kerosene droplets,method of reducing methanol droplet quantity, to rapidly improve the carbon potential of furnace gas, make the surface to absorb carbon, improve the surfacecarbon content, the accelerating as soon as possible, so as to shorten thecarburizing time. Stop adding methanol, kerosene addition is 5.784822mL/min.
In the diffusion and cooling phase, kerosene droplets reduce the amount ofcarbon potential of furnace gas, with the final requirements can be quite. Diffusionphase methanol amount is 4.55mL/min, kerosene dosage was 1.1569144 mL/min.
The cooling stage with the furnace cooling to 770 ℃, holding 15~30min, make the part temperature uniformity, and then baked hardening.
Keywords:    camshaft；20steel；gasification
目 录
1  绪论    1
1.1  凸轮轴零件    1
1.1.1 凸轮轴零件的介绍    1
1.1.2 凸轮轴零件的失效形式及性能要求    2
1.1.3 凸轮轴零件的选材及热处理工艺    3
1.2  20钢的介绍    3
1.2.1  20钢的化学成分    3
1.2.2  20钢的特性及用途    4
1.3 渗碳化学热处理    4
1.3.1 渗碳热处理用钢    4
1.3.2 渗碳热处理方法及其特点    5
1.3.2 渗碳热处理的技术要求    6
1.4  毕业设计的内容及意义    8
2  20钢凸轮轴零件渗碳热处理工艺设计    10
2.1  凸轮轴零件的结构数据及技术要求    10
2.2  凸轮轴零件渗碳方法的确定    10
2.3  凸轮轴零件渗碳设备的确定    11
2.3.1 密封箱式炉    11
2.3.2 井式渗碳炉    13
2.3.3 RQ3系列井式气体渗碳炉    16
2.3.4 凸轮轴零件渗碳炉的确定    17
2.4  凸轮轴零件渗碳介质的确定    17
2.4.1气体渗碳渗剂的性能要求    17
2.4.2 滴注式气体渗碳常用的渗碳介质    18
2.4.3 凸轮轴零件滴注式气体渗碳介质的确定    18
2.5  凸轮轴零件渗碳工艺参数的确定    19 20钢凸轮轴零件渗碳热处理工艺设计(3):http://www.751com.cn/cailiao/lunwen_15354.html