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A study for improving the resistance to fretting corrosion of SCr 420 pinion gear was conducted. Fretting is the damage to contacting surfaces experiencing slight relative reciprocating sliding motion of low amplitude. Fretting corrosion is the fretting damage to unlubricated contacting surfaces accompanied by corrosion, mostly oxidation that occurs if the fretting occurs in air. Two kinds of conventional heat treatment and a newly designed one suggested for improving the resistance to the fretting corrosion of pinion gear were compared each other to find out what is the main factor for generating fretting corrosion phenomenon. Increased carbon potential at both the heating and diffusing zone and reduced time of tempering was found out to be a solution for improving the resistance to fretting corrosion of forged and heat treated gear steel. On the contrary, modified carbo-nitriding using ammonia gas has been getting worse the fretting corrosion problem.

Hood opening systems are usually composed of several parts, such as a release handle, a release cable, and a latch. In this paper, the main cause of ‘fail-to-open’ or ‘hard-to-open’ problem in hood opening system is presented. The test mode was also developed to reproduce these problems. The reproduced failure mode was the same as that of field problems. Moreover, the design guides for preventing these problems are also described.