Influence of Steel Grain Size on Residual Stress in Grinding Processing

Abstract

Abstract. The fine-grained rolling steels NFG600 and the conventional usual rolling steels SM490 were processed by sand paper polishing and mechanical grinding to compare the residual stress generated after processing. The average grain size of NFG600 and SM490 is 3 µm and 15µm respectively. Therefore improvement of mechanical properties for such fine-grained steels is expected, it is important to understand the residual stress state of new fine-grained materials with processing. In this study, multi axial stresses of two kinds of specimens after polishing and grinding were measured by three kinds of analysis methods including cos-ψ method. As a result, as for σ 33 , the stress of NFG was compression, though that of SM490 was tension.

Predicting the Effects of Grain Size on Machining-Induced Residual Stresses in Steels

“…In other words, grain refinement would result in lower tendency for surface tensile RS11 (or higher surface compressive RS11). It is worth mentioning that, the current results are in agreement with the experimental results of Gotoh et al [1], when they grinded two types of steel; a fine-grained rolling steel "NFG600" and a conventional rolling steel "SM490".…”

“…Larger grain size (lower yield strength) resulted in higher surface tensile RS, which was attributed to higher compressive plastic deformation and higher workpiece temperatures. The current results also agree with the experimental findings of Gotoh et al [1].…”

“…Fine-grained steels typically have higher tensile strength according to the well-established Hall-Petch relation, which assumes an inverse square-root dependence of strength upon average grain size [1 -4]. The grain size effect even extends to other mechanical properties, like hardness, wear resistance and fatigue life [1,5]. In addition, grain refinement results in lower ductile-to-brittle transition temperature and increases the penetration depth of X-rays [1], which are used to measure residual stresses (RS).…”

“…The grain size effect even extends to other mechanical properties, like hardness, wear resistance and fatigue life [1,5]. In addition, grain refinement results in lower ductile-to-brittle transition temperature and increases the penetration depth of X-rays [1], which are used to measure residual stresses (RS).…”

“…The study covered grain sizes within the industrial range (45-130 µm). In a study by Gotoh et al [1], the effect of grain size on RS after grinding of steels was examined. Two types of steels, having the same chemical composition, were used; a fine-grained rolling steel "NFG600" (average grain size of 3 µm) and a conventional rolling steel "SM490" (average grain size of 15µm).…”