Hardness-toughness relationship of a boron alloyed quench and tempering steel after different heat treatment cycles

Reinhold Schneider, Katharina Steineder, Yuri Tohima, Masahiro Okumiya

Research output: Chapter in Book/Report/Conference proceedingsConference contribution

Abstract

The hardness-toughness relationship for the steel 42MnNiCrB4-3 was investigated by a dilatometer. This included standard heat treatment (850°C, 30 min), short-cycle heat treatment (950°C, 16 s) and double short-cycle heat treatment (2 x 950°C, 16 s). The tempering process lasted one hour for all samples and temperatures up to 500°C were examined. Furthermore, isothermal transformation treatment (austempering) with 320 / 360 / 400°C were performed. To characterize these heat treatment conditions, three notched impact samples were used. After the dilatometer experiments, impact testing and Vickers micro-hardness testing was performed. Additional investigation on the tested samples comprised XRD, LOM as well as SEM. Regarding the hardness-toughness relationship, there are no significant differences between standard HT and short-cycle HT. The results showed a severe reduction in toughness properties due to the effect of 300°C - brittleness (blue brittleness). Tempering at 200°C provides a good combination of this relationship for each heat treatment condition. The best hardness-toughness relationship was achieved by isothermal treatment at 320°C and 360°C. There is no cleavage fracture at any conditions, but a significant change in fracture surface appearance could be found at the isothermal transformation treatment at 400°C. For all heat treatment conditions tempering at 250°C or higher removes the retained austenite.

Original languageEnglish
Title of host publication23rd International Federation of Heat Treatment and Surface Engineering Congress 2016, IFHTSE 2016
PublisherASM International
Pages418-424
Number of pages7
ISBN (Electronic)9781627081160
Publication statusPublished - 2016
Event23rd International Federation of Heat Treatment and Surface Engineering Congress 2016, IFHTSE 2016 - Savannah, United States
Duration: 18 Apr 201621 Apr 2016

Publication series

Name23rd International Federation of Heat Treatment and Surface Engineering Congress 2016, IFHTSE 2016

Conference

Conference23rd International Federation of Heat Treatment and Surface Engineering Congress 2016, IFHTSE 2016
CountryUnited States
CitySavannah
Period18.04.201621.04.2016

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