Abrasion-Resistant White Cast Iron 23
- 5.3 Rational selection of matrix structure of high chromium white cast iron
First of all many manufacturers prefer to choose the tempered martensite when choosing the matrix structure of high chromium white cast iron. No matter the working condition and the stress state of the castings. Even the less the retained austenite in the matrix is better. The retained austenite can be regarding as the defect of the structure. And even as the standard of the product’s disqualification.
Due to the research results show that the wear behavior of the matrix is different in different wear systems. As a result we can select the matrix according to the wear characteristics and the stress state of the parts. That so as to maximize the potential of the material.
The test results show that the martensitic matrix displays the best abrasion resistance under low stress abrasive wear condition. No matter it is high chromium white cast iron or medium chromium white cast iron. Followed by martensite + bainite + austenite complex matrix. Then it is bainite + austenite. And probably the worst is austenite.
The results of the field assessment confirmed this conclusion. Martensite + bainite + austenite complex matrix of medium chromium white cast iron grinding ball shows the best wear resistance on the gold ball mill. And also shows the minimum crushing rate. Analysis of wear morphology shows that grinding ball wear belongs to abrasive wear which is mainly fatigue peeling mechanism. In conclusion improving the anti fatigue ability of grinding balls is the best way to improve wear resistance and reduce crushing rate of grinding balls.
The results of the wear surface analysis show that in martensite + bainite + austenite matrix. Maybe the impact fatigue exfoliation is obviously smaller than martensite matrix. Furthermore the microcrack is smaller than martensite. Which is related to the distribution of martensite + bainite + austenite basic tissue. It seems like it is easy to produce the crack initiation of carbide.