Formation of Tensile Stress Induced Cracks in Flame Hardening Surface Treatment of 12Cr Blade Steel

Abstract:

This paper reports on the formation of tensile stress induced cracks by the application of a flame hardening to 12Cr steels and the monitoring of the flame hardening process at the desirable residual stress state. During the flame hardening of the steels elastic residual tensile stresses were typically generated due to a phase transformation of austenite into martensite and they became greater by increasing both the process temperature and cooling rate. Eventually the cracks were nucleated and propagated across the prior austenite grain boundaries by a generation of large tensile stress, which was accompanied by a drastic decrease in the tensile stress due to a stress relaxation.

• Periodical: Solid State Phenomena (Volume 118)
• Pages: 191-196
• DOI: https://doi.org/10.4028/www.scientific.net/SSP.118.191
• Online since: December 2006
• Authors: Min Ku Lee, G.H. Kim, K.H. Kim, Sung Mo Hong, Wheung Whoe Kim, Soon Jik Hong, Chang Kyu Rhee
• Keywords: 12Cr Steel, Crack Formation, Flame Hardening, Martensitic Transformation (MT), Residual Stress, Steam Turbine Blade

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