Alternative phase transformation path in cryogenically treated AISI D2 tool steel

Abstract

This study based on dilatometry test and microstructural observations showed a different phase transformation path during conventional heat treatment of AISI D2 tool steel instead of the traditionally expected fully martensitic transformation. Transformation started with carbide precipitation and continued with allotriomorphic ferrite, Widmanstätten ferrite, acicular ferrite, and finally bainite formation. This microstructure showed microhardness value of 730 HV, which is very high for conventionally cooled samples. They are not expected to have gone under martensitic transformation. The results indicated that bainitic transformation take place even at temperatures near 173 K and to obtain fully martensitic microstructure, cooling rates in the range of 50K.s -1 must be utilized.

In situ TEM observation of the microstructure characteristics of the vacuum sintering, sub-zero and heat treatments of Vanadis 23 high-speed steel by adding Cr3C2–TaC–TiC powders

“…Apparently, the XRD analysis results confirmed that sub-zero treatment can indeed remove retained austenite. In other words, the retained austenite had been almost transformed into martensite after subzero treatment, which also agrees with the above literatures and our previous studies [2,15,16]. 2 T + HT, and 0.2 T + SZ specimens.…”

“…It can be improved the mechanical properties by using a series of heat treatments. Cryogenic treatment (also known as sub-zero), as an effective way to improve the properties of tool steels, since it enhances the transformation of retained austenite to martensite [15][16][17][18]. Therefore, we added Cr 3 C 2 -TaC-TiC carbides to Vanadis 23 powders as an innovative composite material, aimed to explore a series of vacuum sintering processes, sub-zero and heat treatments for Vanadis 23 composites, and further examined the effects on the sintering behaviour, strengthening mechanism, and mechanical properties of Cr 3 C 2 -TaC-TiC strengthened Vanadis 23 composite materials.…”

In Situ Study of Phase Transformations during Non-Isothermal Tempering of Bainitic and Martensitic Microstructures

“…This phase transformation causes a remarkable length decrease and can be clearly detected during the dilatometry test [4,9,12,18].…”

Investigation of the strengthening mechanism and corrosion behaviours of Vanadis 4 extra tool steel adding ZrC−TiC powders through vacuum sintering, and sub-zero and heat treatments

“…Cryogenic treatment (also known as sub-zero) is an effective way to improve the properties of tool steels, since it enhances the transformation of austenite to martensite. In recent years, several papers have been published that sub-zero treatment can improve wear resistance of tool steels [16,17]. Normally, the temperature range of sub-zero normally is from −125 to −196°C .…”