Authors: V G Gavriljuk V A Sirosh Yu N Petrov A I Tyshchenko W Theisen A Kortmann
Publish Date: 2014/01/31
Volume: 45, Issue: 5, Pages: 2453-2465
Abstract
Using transmission electron microscopy Mössbauer spectroscopy and measurements of hardness the carbide precipitation during tempering of steel X153CrMoV12 containing mass pct 155C 1190Cr 070V and 086Mo is studied after three treatments quenching at RT and deep cryogenic treatment DCT at 77 K or 123 K −196 °C or −150 °C In contrast to some previous studies no fine carbide precipitation after longtime holding at cryogenic temperatures is detected After quenching at room temperature RT the transient εε′ carbide is precipitated between 373 K and 473 K 100 °C and 200 °C and transformed to cementite starting from 573 K 300 °C In case of DCT at 123 K −150 °C only fine cementite particles are detected after tempering at 373 K 200 °C with their delayed coarsening at higher temperatures Dissolution of cementite and precipitation of alloying element carbides proceed at 773 K 500 °C after quenching at RT although some undissolved cementite plates can also be observed After DCT at 123 K −150 °C the transient εε′ carbide is not precipitated during tempering which is attributed to the intensive isothermal martensitic transformation accompanied by plastic deformation In this case cementite is the only carbide phase precipitated in the temperature range of 573 K to 773 K 300 °C to 500 °C If DCT is carried out at 77 K −196 °C the εε′ carbide is found after tempering at 373 K to 473 K 100 °C to 200 °C Coarse cementite particles and the absence of alloying element carbides constitute a feature of steel subjected to DCT and tempering at 773 K 500 °C As a result a decreased secondary hardness is obtained in comparison with the steel quenched at RT According to Mössbauer studies the structure after DCT and tempering at 773 K 500 °C is characterized by the decreased fraction of the retained austenite and clustering of alloying elements in the α solid solution It is suggested that a competition between the straininduced transformation of the retained austenite and carbide precipitation during the wear can control the life of steel toolsThe authors thank Professor Hans Berns Ruhr University Bochum for a fruitful discussion and valuable remarks concerning the obtained results This study was carried out within the frames of Project STCU 5039 the Science and Technology Centre of Ukraine and the BMWi Project 16 IN 04513
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