Influence of grain size distribution on the Hall–Petch relationship of welded structural steel

Abstract

The strength of polycrystalline metals increases with a decrease in grain size according to the HallPetch relationship. However, heterogeneous microstructures deviate from this relationship depending on the distribution of grain sizes. This paper introduces a rule of mixtures based approach for determining the characteristic length of the microstructure for heterogeneous weld metal. The proposed grain size parameter, the volume-weighted average grain size, is measured experimentally for nine structural steel weld metals and two base materials. The weld metals are found to have a large variety of grain size distributions that are noticeably broader than those of the base material due to differences in phase contents. The results show that the volume-weighted average grain size is able to capture the influence of grain size distribution on the strength of welded structural steel. Based on the experimental results, a modified Hall-Petch relationship is formulated for the strength prediction of heterogeneous microstructures. The modified relationship is also found to be applicable to data from the literature.

Optimal polyhedral description of 3D polycrystals: Method and application to statistical and synchrotron X-ray diffraction data

“…The average grain size, for example, is responsible for the so-called "Hall-Petch strengthening" [1,2] and is important for fatigue resistance [3,4]. The grain size distribution has similar effects, albeit generally less pronounced [5,6]. Of course, these phenomena are directly related to the stress and strain heterogeneities developing at the microstructure scale [7].…”

Characterisation of local grain size variation of welded structural steel

“…1. The grain size characterisation of heterogeneous weld metals was studied by Lehto et al [23]. The grain size measurements revealed that structural steel weld metals exhibit a large variety of grain size distributions that are noticeably broader than those of the base metal.…”

The Influence of Abnormal Segregation Band on Mechanical Properties of Hot Rolled Ferrite/Pearlite Steel Plate

“…measured in this study. Based on the dates in Table 1 and interrelated counting, we figured out that yield strength of different positions is inversely proportional to the average grain size, and they are in keeping with Hall-Petch relation [16].…”

“…According to the strength expression formula raised by Pickering [16], the strength of matrix is express as: propagation [23], the resistance of crack propagation in coarse grain region is smaller. Therefore, it is apt to be the lower energy paths for crack propagation and connectivity, creating conditions for laminated tensile fracture.…”