Experimental quantification of the wear performance of rolls used in industrial rotary straightening of seamless steel tubes

Abstract

Gaining detailed information about the wear performance of work rolls used for rotary straightening of seamless steel tubes is of utmost importance for extending the service life and, thus, for reducing costs and maintenance efforts. However, comparing the wear performance of different work rolls after their use in industrial straightening machines is almost impossible, as roll materials, service conditions and production portfolios are usually quite different. Therefore, this experimental study investigates the wear of two roll materials (high-chromium cast iron, HCCI, and modified cast high-speed steel, HSS) under rolling/sliding contact with selected tube steels (grades L80 and Q125) by using a two-roll test rig. The materials were tested at specified constant contact force, temperature and roll slip to simulate the complex conditions of an industrial straightening process. After each of the test runs the weight loss of the test roll was measured using a precision scale, and the volume loss was captured using an optical 3D geometry scanner. Over the rolling distance or rolling time, respectively, a virtually linear weight/volume loss was observed for steady-state wear beyond the initial run-in phase, which enabled calculating the material-specific wear coefficients of HCCI and HSS for the particular testing conditions. Very similar wear coefficients were determined for both materials, as the microstructure (carbides) and thus the bulk hardness of HCCI and of modified HSS were similar. The specific wear coefficients enabled estimating the service life of industrial work rolls as function of the grade and of the dimension of the straightened steel tubes.