A Novel Methods for Fracture Toughness Evaluation of Tool Steels with Post-Tempering Cryogenic Treatment

Abstract

Cryogenic treatments are usually carried out immediately after quenching, but their use can be extended to post tempering in order to improve their fracture toughness. This research paper focuses on the influence of post-tempering cryogenic treatment on the microstructure and mechanical properties of tempered AISI M2, AISI D2, and X105CrCoMo18 steels. The aforementioned steels have been analysed after tempering and tempering + cryogenic treatment with scanning electron microscopy, X-ray diffraction for residual stress measurements, and micro-and nano-indentation to determine Young's modulus and plasticity factor measurement. Besides the improvement of toughness, a further aim of the present work is the investigation of the pertinence of a novel technique for characterizing the fracture toughness via scratch experiments on cryogenically-treated steels. Results show that the application of post-tempering cryogenic treatment on AISI M2, AISI D2, and X105CrCoMo18 steels induce precipitation of fine and homogeneously dispersed sub-micrometric carbides which do not alter hardness and Young's modulus values, but reduce residual stresses and increase fracture toughness. Finally, scratch test proved to be an alternative simple technique to determine the fracture toughness of cryogenically treated steels.

Effect of Rolling Temperature on the Microstructure and Mechanical Properties of Mg-2Zn-0.4Y Alloy Subjected to Large Strain Rolling

“…In this paper, all the OM figures were taken at the cross-section of RD and normal direction (ND), and the RD of the samples were placed along the horizontal direction. Grain sizes were measured using the public domain software ImageJ (version 1.52a, Bethesda, MD, USA) with the intercept method based on the ASTM standard E112-13 (Standard Test Methods for Determining Average Grain Size) [22][23][24]. On each sample, five test lines were placed randomly and intercepted with at least 20 grains depending on the grain sizes.…”

Influence of geochemistry on toughening behavior of organic-rich shale

“…Seven years ago, we introduced the method of fracture assessment via scratch testing. The theory and Since then, the method has been widely used to characterize reservoir rocks [75], tribological coatings [58,27], steel tools [70], coal [54], and rocks [32], and other appications. The scratch test consists of drawing a Rockwell C diamond stylus across the flat surface of the specimen under a progressively increasing vertical load and a constant scratch speed of 6 mm/min.…”

Enhancement of the mechanical properties of EN52CrMoV4 spring steel by deep cryogenic treatment

“…It can improve the wear resistance and mechanical properties of steels by inducing compressive residual stress, reducing / eliminating the retained austenite, homogenizing the grain structure and triggering the secondary carbide precipitation [11][12][13][14]. Especially, application of the deep cryo-genic treatment improves the dimensional stability and service life of the tool steels that the tool consumption and production costs are reduced significantly [15][16][17][18]. Moreover, it has no harmful emission or waste by-products.…”