The Non-Destructive Method of Elasticity Modulus Measurement of Valve Seats from STELLITE with Various Cryogenic Stavs

Function and straining of piston combustion engine valve seats. Utrasound diagnostics of composite valve seats (steel-graphite) durability. Pilot experiment in region of cryogennic temperature influence on mechanical properties of cobalt hot wear resistant alloys of STELLITE group determination. Cobalt alloys are exploited due their excellent mechanical properties at high temperatures as a matter for valve seats of gas combustion engines. From the technological view the valve seats are frozen in liquid nitrogen before assembling because of big assembling overlaps which should assure reliable anchoring of valve seats in heads of cylinders. The anchoring force depends on elasticity modulus of valve seat and head of cylinders. The non-destructive method of elasticity modulus measurement in the region of bore for valve seats placing of composite cylinder heads. In the case of undercritical value there is a danger of falling out of seat from cylinders head under influence of thermal expansivity of head alone. The measurement of sound speed and magnetic properties of valve seats from STELLITE 6 and STELLITE 12 with various cryogennic stays. The expressive minimum of sound speed at critical cryogennic stay. The link proof of sound speed minimum and elasticity modulus by non-destructive measurement of valve seat ring bent at hardnessmeter loading. The mathematical pattern of calculation. This contribution serves to finding if this manufacturing technology of valve heads has an effect on useful properties of valve seats – direction of next research.