发动机机体型内退火去应力工艺方案实践

Annealing Process of Eliminating Stress Within Mold for Engine Block

利用树脂砂具有很好的保温性能,可以使得最小吃砂量保持在200 mm左右的特点,同时控制原铁液中的碳（3.6%~3.8%）、锰（≤0.1%）、终硅（2.8%~2.9%）,控制浇注温度在1 355~1 365℃,并采取型内保温措施（250 h）,可以使得某大型船用柴油机体在铸态下得到超过90%的铁素体组织,铸件的抗拉强度≥390 MPa,伸长率≥14%,布氏硬度135~185 HBW,机体缸孔和凸轮轴孔等区域Ⅰ最大残余应力在±50 MPa,内部筋板区域最大残余应力在±50 MPa,可实现正常去应力退火后的效果。

Utilizing the good characteristic of resin sand in thermal insulation performance to make the least sand thickness above 200 mm, at the same time, controlling the original liquid iron composition of 3.6%~3.8%C, ≤0.1%Mn and 2.8% 2.9%Si, the pouting temperature of 1 355 - 1 365 ℃ and keeping for 250 h within the mold, can make a large marine diesel body of ductile iron obtain more than 90% ferrite microstructure in as-cast, the tensile strength of more than 390 MPa, the elongation of more than I4%, and the brindl hardnes of 135 - 185 HBW. The maximum residual stress is 〉50 MPa in cylinder holes and the CAM shatt hole area, and ＋100 MPa in internal ribs.