Analysis of the Causes of Steel Rod Fracture in a Rod Mill?

Steel grinding rods for rod mills—wear-resistant steel rods used in a wide range of rod mills in mining, chemical processing, cement plants, power plants, and for processing quartz sand and silica sand.

1. Analysis of the stick-breaking phenomenon:

(1) Cause:

A. Material: Internal porosity. This is a problem with steel billets produced by steel mills; only very large-scale mills can meet the technical requirements for a dense internal structure, particularly for billets with diameters of 70 mm or more. Although most mills can successfully produce these billets, their compression ratio and hardenability are low, resulting in a non-compact microstructure.

B. Manufacturing Process: Internal residual stresses have not been relieved. Bar breakage is akin to an explosion—it originates from within. The steelmaking process for producing steel bars is similar to blowing up a balloon: the internal residual stresses must be eliminated to prevent bar breakage.

(2) Solution:

A. Focus on material quality. a. Use materials from China’s largest steel mills whenever possible; b. Employ well-established heat-treatment processes.

B. Processing Technology: Our company’s products can significantly enhance the wear resistance of steel bars and prevent bar breakage.

C. Dimensions and specifications can be flexibly customized; steel bars typically sourced from mills are 6 meters long, so if you require 4-meter lengths, the remaining 2 meters after cutting will be wasted. Our company offers custom-length fabrication to meet your exact requirements.

D. Our company’s newly developed, wear-resistant steel rods—produced using innovative materials and processes—extend service life, reduce costs, and alleviate workers’ physical labor. No more worrying about daily downtime to reload the mill with steel rods, while significantly boosting production output.

2. Regarding the hardness of steel rods

The optimal hardness for a steel rod is 45–50 HRC; below this range it is too soft and wear-resistant, while above it becomes excessively hard, brittle, and prone to breakage. Furthermore, in terms of manufacturing processes, domestic producers can only achieve a surface hardness of HRC 45 or higher over a maximum depth of 1 centimeter, and once that 1-centimeter layer is ground away, the rod’s properties revert to those of plain round steel.

Our company manufactures wear-resistant steel rods in accordance with international standards, which significantly enhances their overall performance. For example, while typical steel rods have a surface hardness of HRC 45 and a core hardness of HRC 10, our rods can achieve a surface hardness of HRC 50 and a core hardness of HRC 25.

3. Differences among wear-resistant steel bars, steel bars, and round bars

Round steel is a raw material produced by steel mills, not a finished product. Using it to manufacture grinding rods for rod mills leads to numerous problems, such as rod breakage and failure (with both ends becoming excessively tapered), and its hardness is only 20, making it utterly non-wear-resistant!

Steel rods are manufactured by further processing round steel bars; their surface hardness is 45–50, making the surface highly wear-resistant while the core remains relatively soft and less wear-resistant.