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随着内燃机向高速、增压、高负荷方向发展,进排气门的工况越趋恶劣,因此对材料及显微组织的选择提出了更高的要求。目前国内中小功率内燃机进气门一般都采用40Cr,4 Cr_g Si_2制造、排气门采用4 Cr_9 Si_2,5 Cr_(21)Mn_9NI_4制造。进气门工作温度一般为200—450℃、排气门的工作温度一般为600—850℃。工作过程中除承受机械磨损和冲击之外,还受到交变应力及高温气流的腐蚀和冲刷作用。高温下,排气门本身的变形,以及多种原因引起的气阀座与导管的不同心,都会产生交变弯曲应力(见
With the development of high-speed, supercharged and high-load internal combustion engines, the operating conditions of the intake and exhaust valves are becoming worse and worse. Therefore, higher requirements are placed on the choice of materials and microstructures. At present, the intake valves of small and medium power internal combustion engines are generally made of 40 Cr, 4 Cr_g Si 2, and the exhaust valve is made of 4 Cr_9 Si_2, 5 Cr_ (21) Mn_9NI_4. Intake valve operating temperature is generally 200-450 ℃, exhaust valve operating temperature is generally 600-850 ℃. In addition to bearing the mechanical wear and tear in the work process, but also by alternating stress and high temperature air erosion and erosion. High temperature, the exhaust valve itself deformation, and a variety of reasons caused by different valve seat and catheter heart, will have alternating bending stress (see