Experimental Investigations on the relation of the lubricant's flash point and quality of the piston made from aluminium alloy for its application in internal combustion engines

摘要

In the current paper there was made an attempt to develop an experimental method of physical (lubricant's flash point T_(fp)) and subjective (forgings' quality) parameters coupling for hot isothermal-like forging operation. The quality forgings could be manufactured both by high and low lubricant's flash point. The increase of T_(fp) value in exothermal reaction follows to the increase of the released heat amount by the lubricant, because it needs more initial activation energy transmitted from the external source to initialize transformation of the material from one aggregate state into another (from liquid or solid into gaseous or sol-like). This can prevent the temperature decrease on the punch due to strong convective heat transfer with the environment through the building of the isolation temperature shield on the punch contact surface at the beginning of the punch stroke. On the other hand it can cause the defect building on the forgings like penetrations, which could not be eliminated during cleaning operation before mechanical treatment due to chemical interactions of the dissolved active agents, or unfilled sections.