Thermal Fatigue Behaviors Of Biomimetic Units On Compacted Graphite Cast Iron Processed By Laser In Water

As we all known, the wearing resistance and the thermal fatigue resistance are two key factors which had effect on the compacted graphite cast iron2 (CGI) train brake disc life. So while the wearing resistance of CGI was improved, its thermal fatigue resistance should be study. The bionic coupling units on the CGI surface which were processed by laser in water medium and the basal corpuscle formed a surface which was similar to the organism body surface. The units had finer microscopic constitution. The test results showed that the units could improve the wearing resistance of the CGI. But there were cracks on the units'surface and the cracks would proliferate after the lower thermal fatigue test cycles. It would affect the thermal fatigue resistance of the bionic coupling samples. For reducing the impact, the way how to reduce the cracks on the surface of units was researched. This work is applied and laid the foundation for the research on the thermal fatigue resistance of the bionic coupling samples. This text mainly researched how to improve the thermal fatigue resistance of bionic coupling units on the CGI surface, in order to improve the resistance of resistance of bionic coupling units processed by laser in water. in water medium and the researches have laid the foundation for improving the resistance of compacted graphite cast iron bionic coupling materials.This text had researched the thermal fatigue resistance of units processed in air and in water medium respectively. The result showed that the thermal fatigue resistance of units processed in water medium is worse. The different treatments were used to improve the units thermal fatigue resistance. The best way was found.There is one observation after 100 times thermal fatigue resistance in the tests.Through to measure and statistics the length and angle of cracks by 50 times optical microscope have concluded the following results:1. The amount of cracks on units processed in water is more 2.19 times than in air. The amount of traverse cracks mainly affecting the capability of units is more 1.76 times than in air. Because of this ,the result is that: the thermal fatigue resistance of processing units in water medium is worse than in air medium,2. The process of stress relieving ,namely preheat, preheat and post heat, post heat, the second fusion and electrical impulse dos not change the tissue of the units at fusion areas The tissue mainly is the Metamorphosis ledeburite( martensite and carbide), its rest is ferrite and retained austenite.3. The process of stress relieving, post heat, the second fusion and electrical impulse can improve the thermal fatigue resistance of units processed in water. The following result is that:1) The rise of cracks and the traverse cracks on units with stress relieving is lower than with water. The rise is 69 percent,83.6 percent and 57.9 percent lower than that of rise on the units processed with water medium. Similarly, the amount of traverse cracks is 88.9 percent,87.5 percent,88.9 percent lower.2) The rise of cracks on units with the second fusion is 75.4 percent lower than that that of rise on the units processed with water medium; The amount of traverse cracks is 59.7 percent lower.3) The rise of cracks on units with electrical impulse is 80.7 percent lower than that that of rise on the units processed with water medium. The amount of traverse cracks is 31.9 percent lower.