Wang Yipan, Wang Fazhan, Yu Wenbo, Wang Yuanjun, Qi Zhanyu
School of Mechanical and Electrical Engineering, Xi'an University of Architecture & Technology, Xi'an, 710055, China.
School of Mechanical and Electrical Engineering, Xi'an University of Architecture & Technology, Xi'an, 710055, China.
J Mol Graph Model. 2023 Jan;118:108354. doi: 10.1016/j.jmgm.2022.108354. Epub 2022 Oct 5.
In order to research the effect pattern of MnS inclusions on free-cutting steel, we study the microstructure evolution, the damage mechanism and the mechanical properties in free-cutting steel in the presence of MnS inclusions. Spindle shaped MnS is added as inclusions within the free-cutting steel. The mechanical properties were found to change when inclusions were present. The gained results show that the formation of voids causing fracture starts from the interface inside the matrix close to the MnS. From the point of view of nanocomposite strength, the main effect of MnS inclusions is related to stress concentration, leading to the effect of increased stresses near the interface between the interior of the matrix and the inclusions. The inclusions have lower Young's modulus and lower dislocation activity, resulting in smaller deformation of the alloy system, larger interfacial stress concentrations and earlier hole formation. The maximum strain and stress regions of the alloy also appear near the MnS inclusions, which leads to the formation of defects near the MnS inclusions and then fracture of the alloy. MnS inclusions adversely affect the tensile properties of the alloy, such as Young's modulus, yield stress and yield strain. By comparing the stress-strain curves of single crystal iron and alloy containing MnS inclusions, it is indicated that the yield strength of the latter decreases. Slip bands and dislocation lines are first generated around the MnS inclusion, and the phase transition is induced from the original single BCC structure to FCC, HCP and amorphous structures, and the atoms of FCC, HCP and amorphous structures increase with increasing strain, while those of BCC structure decrease, especially after yield strain. This study is significant for understanding the effect of inclusions on the mechanical laws and fracture mechanisms of the alloy.
为了研究MnS夹杂物对易切削钢的影响规律，我们研究了存在MnS夹杂物时易切削钢的微观结构演变、损伤机制和力学性能。在易切削钢中添加纺锤形MnS作为夹杂物。发现存在夹杂物时力学性能会发生变化。所得结果表明，导致断裂的孔洞形成始于基体内部靠近MnS的界面处。从纳米复合材料强度的角度来看，MnS夹杂物的主要作用与应力集中有关，导致基体内部与夹杂物之间界面附近的应力增加。夹杂物具有较低的杨氏模量和较低的位错活性，导致合金系统变形较小、界面应力集中较大且孔洞形成较早。合金的最大应变和应力区域也出现在MnS夹杂物附近，这导致MnS夹杂物附近形成缺陷，进而导致合金断裂。MnS夹杂物对合金的拉伸性能，如杨氏模量、屈服应力和屈服应变有不利影响。通过比较单晶铁和含有MnS夹杂物的合金的应力-应变曲线，表明后者的屈服强度降低。滑移带和位错线首先在MnS夹杂物周围产生，并诱导从原始的单一体心立方结构转变为面心立方、密排六方和非晶结构，随着应变增加，面心立方、密排六方和非晶结构的原子增加，而体心立方结构的原子减少，尤其是在屈服应变之后。该研究对于理解夹杂物对合金力学规律和断裂机制的影响具有重要意义。
