Crack in neck of hollow shaft is a very serious malfunction, main cause of the crack include: foundry defect, centralized stress, quality problems of welding and heattreatment.
By experiment and production practice, it was pointed out that such crack could be prevented by control of pick forming, heattreatment and grinding process.
After the heattreatment process was improved on, factors inducing part to crack were decreased, the quenching of part became easy to operate and the heattreatment quality of part was ensured.