The 9Ni martensitic steels have a martensitic microstructure which contains retained austenite after solution heat treatment and water quenching. Under low cycle fatigue. extrusions formed at the surface of the material and were very close to martensite lath boundaries. The presence of retained austenite at martensite laths has been highly suspected to impact the cyclic plasticity. https://www.roneverhart.com/Polly-Pocket-Polly-Lila-Tropicool-Pineapple-Wearable-Purse-Compact/