Large inclusions have a significant impact on the fatigue life of bearing steel.The evaluation methods for inclusions in bearing steel were compared and analyzed.Bearing steel were tested by high frequence ultrasonic C-scan,and using metallographic method to validate the results.The results showed that the testing method of high frequence ultrasonic C-scan was effective for the testing of large inclusions in bearing steel.
通过对21-4N冷拉棒材超声波探伤漏检原因的分析,说明单纯采用超声波探伤方法,很难保证其缺陷的全部检出,应采用多种探伤方法以互补,保证缺陷不漏检。
The differences of the results of the ultrasonic testing in the different time had been analyzed for the steel 5140 which were produced by rolling of continuous casting billet.It was obtained that the effects of the stress cracks expanding in the steel 5140 on results of the ultrasonic testing were obvious.The methods of solving the problem have been provided in the same time.
The construction and the functions of component parts of the intelligent analytical instruments are de- scribed.The causes of common troubles of these instruments are analyzed and troubleshooting methods are proposed.
The structure and properties of steel with three kinds heat treatment processes-quenched at 880 ℃ for 30 min oil cooling + tempered at 600 ℃ for 60 min air cooling,normalized at 860 ℃ for 30 min air cooling and two-phase region subcritical treated at 780 ℃ for 30 min air cooling,in order to get a simplified heat treatment process of 40SiMnCrNiMo for rock drill tools.The results showed that the HV microhardness value at bainite region of subcritical heat treated steel lowed than that of normalized steel and V-notched impact energy was 30 J higher than that of normalized steel(12 J)and approached to that of quenched and tempered steel(40 J).The test for service life of rock drill tools indicated that as compared with average 10.78 m drill pace of advance of normalized steel tool,the average drill pace of advance of subcritical treated steel tools was 108.30 m to meet the requirement of use and to be available to replace quenched and tempered drill tools.
