轮毂车轮高强度螺栓选材

Material selection of high strength bolt for hub wheel

轮毂车轮螺栓在服役过程中要求具有载荷承受较大,尺寸精度较高,外观质量较好等特点。轮毂车轮螺栓用钢必须有足够高的抗拉强度以及较高的疲劳抗力和冲击韧度,足够的塑性、韧性。介绍常用的ML15MnVB、ML20MnTiB,10B28钢的化学成分和轮毂车轮螺栓生产工艺。10B28钢热轧态组织为铁素体+珠光体,表面硬度为78～95 HRB,塑性较好,经740～760℃球化退火后,塑性进一步提高,变形率达80%～85%。ML15MnVB,ML20MnTiB,10B28钢冶炼过程中增加了铁水预处理,控制S,P质量分数小于0.020%,降低夹杂物含量;连铸时采用全程保护浇注、电磁搅拌;安装在线红外线动态外径检测仪和电磁涡流测量装置,有效保证冷镦钢的质量。对轮毂车轮螺栓用钢热处理工艺进行了优化。

Hub wheel bolts in service should have the following characteristic such as load standing heavy, high dimension- al accuracy, appearance quality high. Steel for huh wheel bolts must have enough high tensile strength, higher fatigue re- sistance and impact toughness, enough plasticity and ductility. The chemical composition of common ML15MnVB, ML20MnTiB, 10B28 steel and hub wheal bolt production process are introduced. 10B28 steel hot rolling microstructure is ferrite and pearlite, surface hardness is 78 - 95 HRB, plasticity is good. After 740 - 760 ℃ spheroidizing annealing, the plasticity is further improved, deformation rate reaches 80% - 85%. To add hot metal pretreatment when ML15MnVB, ML20MnTiB, 10B28 steel is in smelting process, which control mass fraction of sulphur and phosphorus less than 0. 020%, decrease inclusion content. Full protection pouring and electromagnetic stirring are adopted in continuous cast- ing. Online infrared detector dynamic outer diameter and eddy current measurement device are installed to guarantee quality of cold heading steel effectively. The heat treatment process of steel for hub wheel bolt is optimized.