Failure Research Of The Inputting Shaft For The High Speed Wire-rod Finishing Mill In Chang Gang

Production is seriously affected by the frequently invalidation of the inputting shaft on the high speed wire-rod finishing mill. stylebooks needed were collected by carefully observation, samples collection and data statistic.Microstructure observation of the inputting shaft found that the low temper temperature in heat treatment (slack quench) of the shaft led to the formation of troostite with the morphology of martansite and the falling of the toughness was the reason why the lives of the slack quenched product were shorter than the hot rolled ones. Scaning electron telescope showed, source of crack existed both in slack quenched and untreated shaft, these kinds of crack source made up of impurity, notch and the root of notch. Large quantity of miro-holes and micro cracks existed around the crack source expand quick under stress, which led to the destroy of the equipment. Destroy of the shaft was caused by the character of fatigue and cleavage frature Microstructure analysis and combination property research show, mechanical behaviour is determined by microstructure, which is in accord with the practical situation. Strength and reliability study show they can meet the requirement. Effective method is suggested to enhance the strength and reliability.By microstructure observation, crack initiation and expanding reach and mechanics analysis, Conclusion of the study is achieved as follow: microstructure and heat treatment is the main reason of the fracture of the shaft, and the mechanics approach and calculation here can help to improve the property of inputting shaft.This work set an important reference for the analysis of the invalid part.So the process of the heat treatment should be mended to ensure the better general properties, high grade steel materials should be chosen to prevent cracks, the size of the inputting shaft should be optimized to improve the anti-deformation ability and reliability. By taking the above measures, the problems were resolved, 500,000 yuan` income was added annually, and favorable economy and society benefit were achieved.