ISSN:
1013-9826
Source:
Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
The influence of surface treatment such as nitriding, TNHT(Ti Nano Heat-treatment,PHILOS TECHNOLOGIES, INC.) and PVD coating on the thermal crack propagation behavior ofhot work die steel was investigated. To examine the thermal fatigue resistance, the cyclic thermalshock system consisted of induction heating and water spray quenching unit was constructed andLm is proposed as the index representing the susceptibility to crack initiation and propagation.Thermal stress depending on test temperature was also simulated by FEM. The TNHT specimenshowed lower Lm value than as-heat treated specimen but, in the case of maximum and averagecrack length, the TNHT specimen exhibited higher value than those of as-heat treated specimen.This means that the small number of large cracks were initiated and propagated selectively in theTNHT specimen. This result can be caused by two contrary effects of diffusion layer, those areintroduction of the residual compressive stress good for mitigation of thermal tensile stress and veryhigh surface hardness harmful for crack initiation. However, Lm value of salt-bath nitridingspecimen was very high due to the white layer in spite of the existence of diffusion layer
Type of Medium:
Electronic Resource
URL:
http://www.tib-hannover.de/fulltexts/2011/0528/01/52/transtech_doi~10.4028%252Fwww.scientific.net%252FKEM.326-328.1173.pdf
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