Metallographic diagram of 25Si2Mn2MoV (1100℃×40min air cooling)

Microstructure Analysis of 25Si2Mn2MoV( 1100℃×40min air cooling) Steel

In this study, the microstructure of 25Si2Mn2MoV(1100℃×40min air cooling) steel was studied. The alloy was heated in a furnace and held at 1100℃ for 40 minutes. After process, it was air cooled to room temperature. The sample was then tested for various properties, such as microstructure. The microstructure of the alloy was observed by optical microscopy and scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDS).

Optical microscopy observations of 25Si2Mn2MoV steel showed a homogeneous microstructure consisting of ferrite and pearlite. The ferrite grains were located in the ferritic regions between pearlite colonies and were of irregular shape and irregularly spaced in the microstructure. The pearlite colonies were of slightly rounded shape, consisting of lamellae of ferrite and cementite. The austenite grain size was small, too small to see with optical microscope.

The SEM images of 25Si2Mn2MoV steel showed an abundance of surface oxide particles. The oxide particles were mainly in the form of iron oxide and/or chromium oxide. Other inclusions such as AlN, Al2O3 and SiO2 were also present. The ferrite grains were of different shapes, sizes, and spacing within the microstructure. The ferrite grains had irregular size and spacing, but they were generally larger and more sparsely spaced than in optical microscope images. The pearlite colonies were also different in size and shape, comprised of alternating lamellae of ferrite and cementite.

The EDS analysis indicated that the grain boundaries of both ferrite and pearlite had a high chromium content and low oxygen content. The ferrite grains had been fully transformed to pearlite, hence the chromium content of the grain boundaries was high. The EDS analysis also revealed that there were small amounts of nitrogen and phosphorus in the microstructure.

In conclusion,25Si2Mn2MoV(1100℃×40min air cooling) steel has a homogeneous microstructure, consisting of ferrite and pearlite. The ferrite is of irregular shape and spaced within the microstructure, while pearlite colonies have alternating lamellae of ferrite and cementite. The grain boundaries of ferrite have a high chromium content and low oxygen content. The microstructure contains small amounts of nitrogen and phosphorus, as well as surface oxide particles, mainly in the form of iron oxide and/or chromium oxide.

介绍

The microstructure of 25Si2Mn2MoV after cooling to room temperature after air quenching at 1100 degrees Celsius for 40 minutes is primarily austenite. Austenite forms two different components: ferrite and pearlite. Ferrite is a low carbon iron, which is formed by cooled austenite, and pearlite is formed by the layering of ferrite and cementite.

The austenitic matrix of 25Si2Mn2MoV is composed of ferrite, pearlite, and intergranular ferrite. The microstructure of ferrite is the most obvious, distributed in the form of strips and blocks with a certain length and thickness. The pearlite of 25Si2Mn2MoV is in the form of a cream-coloured lamellar structure, and the intergranular ferrite is distributed between the ferrite and the pearlite in the form of a narrow region, resembling a thin line.

In addition, 25Si2Mn2MoV has excellent mechanical properties, such as high strength and good toughness, making it ideal for use in large cross-section parts such as construction parts, building materials and machine tools, as well as in high temperature and large parts with fatigue strength requirements that must reach a higher level.

25Si2Mn2MoV空冷1100℃×40min之后冷却至室温下的金相图，主要是奥氏体。奥氏体形成两种不同成分：低碳铁铁素，并且铁素由冷却的奥氏体形成，而珠光体则是由铁素和渗碳体分层而形成。

25Si2Mn2MoV的奥氏体基质由铁素，珠光体和晶间铁素组成。从金相图中可以看到，铁素的微观形貌最为明显的，以一定长度和厚度的线条块分布。25Si2Mn2MoV的珠光体以乳白色的板条状结构存在，而晶间铁素则分布在铁素和珠光体之间，以宛如薄膜的细线的形式分布。

此外，25Si2Mn2MoV有着优良的力学性能，如高强度与良好的韧性，使其成为大断面零件，如建筑零件，建材和机床以及高温和大零件需要达到更高水平疲劳强度要求的理想材料。