Damping properties of austenitic stainless steels containing strain-induced martensite

Damping properties of two austenitic stainless steel grades, EN 1.4318 and EN 1.4301, were investigated. The test materials were cold rolled to different reductions and damping capacity was measured as a function of temperature with an internal friction method. Microstructures of the test materials were studied by means of X-ray diffraction (XRD) and magnetic measurements. The results showed that damping capacity of the studied materials depended on the amounts of strain-induced epsilon- and alpha'-martensite phases. At temperatures around 0 C, highest damping capacity was achieved with cold rolling reduction of 10 to 15 pct. This behavior is related to the existence of epsilon-martensite and stacking faults. Internal friction peak due to alpha'-martensite phase was present at the temperature of 130 degreesC. Strain aging heat treatment at 200 degreesC for 20 minutes decreased the damping capacity in the entire studied temperature range.