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The influence of tempering on cleavage fracture stress and transition behaviour of bainitic 2.25Cr1Mo steel
Author(s) -
Holzmann Miloslav,
Vlach Bohumil,
Man Jiří,
Krejčí Jan
Publication year - 1995
Publication title -
steel research
Language(s) - English
Resource type - Journals
eISSN - 1869-344X
pISSN - 0177-4832
DOI - 10.1002/srin.199501123
Subject(s) - tempering , charpy impact test , materials science , cleavage (geology) , brittle fracture , metallurgy , brittleness , microstructure , carbide , composite material , fracture (geology) , dislocation
The effect of tempering on the mechanical properties and on the cleavage fracture stress of bainitic 2.25Cr1Mo steel was studied in a variety of structures with the Hollomon‐Jaffe parameter M ranging between 18.23 × 10 3 and 21.70 × 10 3 . The rapid decrease in yield stress and UTS was observed up to value M = 20 × 10 3 . For values M > 20 × 10 3 the reduction of yield stress and UTS slows down. The cleavage fracture stress continuously decreases with increasing value of M . Concurrently, the changes in dislocation density and in carbide size, morphology and distribution were observed. Various theories of cleavage origin of tempered bainitic microstructures are discussed. The transition temperatures, determined from impact Charpy test, reach minimum at M = 20 × 10 3 . Using Orowan's theory of initiation of the brittle fracture in steels, the minimum of transition temperatures may be explained by the different reduction rates of cleavage fracture stress and yield stress with value of M .