Materials Failure and Performance Analysis for Engine VSI Applications
As for any engineering materials, premature failures can take place in engine a valve seat insert (VSI) during dynamometer test or fielding engine run. If a material failure of engine valvetrain component has never occurred in dynamometer or field engine test then either the component is substantial overdesigned thus uncompetitive or ineffective testing parameters are involved.
Historically, a wide range of commercial high temperature wear resistance alloys have been adopted to make VSI for a variety of engine applications. However, the demand of high-performance wear and corrosion resistance alloys specifically for engine valvetrain application became unequivocally urgent to enable valvetrain components can effectively function with ever stringent emission regulation along with industry fuel efficiency guidelines in last two decades. Some sophisticated VSI alloys have been developed to meet the engineering challenges in recent years. In some cases, new VSIs worked for 1,000,000 miles for a heavy-duty engine in a field run performance without a valve lash adjustment. At the same time, with the new engine combustion behavior and high ratio of power output to fuel consumption, the service condition for valvetrain component is beyond normally defined harsh definition. With high temperature gradient and dry contact between valve and VSIs service conditions, some common VSI materials failure modes/mechanisms for valvetrain component have emerged.
In this presentation, some common VSI materials failure mechanisms such as eccentric wear, hot corrosion, bending rupture, thermal fatigue cracking were discussed and illustrated with actual failure cases.