我厂生产的S195柴油机飞轮和机体的材质均为HT20—40。在飞轮开箱并清砂后,有时发现在轮缘和轮幅的交界处产生裂纹,如图1所示。裂纹外形曲折,裂口严重,稍呈黑色,为典型的热裂纹。机体上后盖板面在铣削加工后发现裂口较直,没有分叉的冷裂纹。裂纹产生部位见图2。裂纹全部从铸件内侧壁产生,向外扩展,其长度为10～15mm,深5～10mm,有时因冷裂造成的废品高达10～15 I plant the S195 diesel flywheel and body material are HT20-40. After the flywheel is unpacked and cleared of sand, cracks are sometimes found at the juncture of the rim and the spokes, as shown in Figure 1. Crack shape twists and turns, a serious gap, a little black, as a typical hot crack. After the body surface of the back cover in the milling process found that cracks more straight, no bifurcation of cold cracks. Crack generation site shown in Figure 2. The cracks are all generated from the inner side wall of the casting and expand outwardly. The length of the crack is 10-15mm and the depth is 5-10mm. The scrap caused by cold cracking sometimes reaches 10-15