Fracture analysis

Background introduction

Fracture analysis includes two methods: macroscopic analysis and microscopic analysis. Macroscopic analysis only requires the use of magnifying glasses and low-power microscopes, which can observe and analyze the fracture surface at low magnifications, obtain the overall characteristics of the fracture surface, and to some extent understand the cause of damage; Microscopic analysis is based on macroscopic analysis, using instruments such as electron microscopes to further identify the pathways, properties, environmental media, and temperature that affect fracture, and to further determine the causes and mechanisms of fracture in detail.

Testing items and equipment

Macroscopic fracture analysis

Through macroscopic fracture analysis, the nature of the fracture and the entire process of the fracture accident can be determined, providing goals and tasks for further microscopic fracture analysis. Macroscopic fracture analysis is the premise and foundation of microscopic fracture analysis.

Testing equipment: reading microscope, stereomicroscope

Microscopic fracture analysis

The microscopic analysis of the fracture surface is achieved through optical microscopy and scanning electron microscopy. Due to the limitation of depth of field, optical microscopes can only roughly observe relatively flat fractures such as cleavage fractures and fatigue fractures, and cannot observe transgranular and transgranular fractures with obvious plastic deformation. Even for flat fractures, it is difficult to conduct large-scale continuous observation and the resolution is low. However, optical microscopes can perform polarized light analysis on certain tissue structures on the fracture surface, and can also observe color changes in different areas of the fracture surface, which plays an important role in the diagnosis of fracture properties. Scanning electron microscopy has a large depth of field, which can study rough fracture surfaces and obtain clear images. The magnification can vary continuously between 10 times and 100000 times, making it easier to observe the details of the fracture surface.

Testing equipment: metallographic microscope, scanning electron microscope