Influence of Environment, Temperature and Chemical Composition on the Microstructural Deterioration of CrNi Steels during Friction

✍ Scribed by H. Pinto; A. R. Pyzalla; W. Hübner; K. Aßmus

• Publisher: John Wiley and Sons
• Year: 2004
• Tongue: English
• Weight: 334 KB
• Volume: 35
• Category: Article
• ISSN: 0933-5137
• DOI: 10.1002/mawe.200400821

✦ Synopsis

Abstract

Austenitic stainless steels are materials commonly used in cryotechnology. At extremely low temperatures these steels still exhibit good mechanical properties along with sufficient ductility. However high mechanical loads combined with low temperatures may induce martensitic transfomation. Martensite leads to brittle failure of machine components, which operate at cryogenic temperatures, and disturbs the superconductive effect due to its ferromagnetism.

The aim of the present work was the investigation of the influence of temperature, environment and loading parameters on the martensitic transformation and the microstructural deterioration of three austenitic CrNi steels. X‐ray diffraction and microscopy studies were carried out on samples worn at room temperature in air with different humidities, at 77 K in LN~2~, at 20 K in LH~2~ and at 4.2 K in LHe. Results show that martensitic transformation in FeCrNi alloys during friction can be supressed by a slightly increased Ni‐content. A decrease of temperature causes changes in the deformation mechanisms and results in embrittlement. In liquid hydrogen a marked deterioration of the microstructure was observed.