汽车后桥齿用22CrMoH热轧圆钢带状组织控制

Strip structure control of 22CrMoH hot rolled round steel for automobile rear axle teeth

围绕汽车后桥齿用22CrMoH钢,通过开展连铸正交试验,优化连铸过程电磁搅拌工艺,改善连铸坯横截面成分偏析,在轧制过程中采用大压下量的开坯轧制工艺,在奥氏体未再结晶区进行多道次大压下量变形轧制,促进圆钢心部组织动态再结晶,从而改善齿轮钢热轧圆钢一次带状组织,改善汽车后桥齿轮热处理变形。采用上述工艺技术制备的重载汽车后桥齿用22CrMoH热轧圆钢,平衡组织状态下的带状组织由原来2.5~3.0级降低至1.5~2.0级,齿轮热处理变形合格率由原来的73%提高到94%,满足了客户技术要求。

Orthogonal experiments of continuous casting were conducted using 22CrMoH steel for rear axle teeth of automo⁃biles to optimize the electromagnetic stirring process in continuous casting and to improve the composition segregation in cross section of casting bloom.The large reduction rolling in uncrystallized region of austenite was adopted in cogging roll⁃ing process to promote the dynamic recrystallization of the center structure of the round steel,thus improving the primary banded structure of the hot⁃rolled round steel as well as the heat treatment deformation of rear axle gear.After using these measures,the banded structure of 22CrMoH hot rolled round steel for automobile rear axle teeth had reduced from Grade 2.5-3.0 to Grade 1.5-2.0 under equilibrium structure conditions,and the qualified rate of heat treatment deformation increased from 73%to 94%,which could meet the technical requirements of customers.