Development of Hot Rolled Coil of 540 MPA Class High Strength Low Alloy Steel for Rock Bolt Applications

by Agung Baskoro, Sumadi, Ahmad Desrianto

Publisher - PT Krakatau Steel, Indonesia

Category - General Novel

Steels are widely used as raw material in many applications, which one of them is as a raw material for rock bolt in mining application. In Indonesia, the steel for this application is also commonly used since several years ago. Rock bolt is a long anchor bolt, for stabilizing rock excavations, which may be tunnels or rock cuts. Steel for rock bolt application requires not only high strength but also good stiffness and small deflection to ensure the rock bolt did not pulled up after being pre loaded. The requirement of mechanical properties of the steel can be fulfilled by chemical composition adjustment and appropriate controlled rolling. This work is concerned with the development of 540 MPa Class High Strength Low Alloy (HSLA) steel strips for mining rock bolt applications. The addition of small amount of grain refinements strengthening elements up to 0.03% Nb and 0.02% Ti into steel containing 0.17% C and 1.5% Mn, combined with controlled rolling process resulted in high yield strength of 420 ~ 500 MPa, tensile strength of 560 ~ 600 MPa, fine ferrite grain size of 3.5 – 4.0 µm and the most importantly high stiffness properties has been developed.

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