Fracture Analysis of High Chromium Cast Iron Roll on CSP Mill

A roll barrel breakdown accident took place on CSP mill. After investigating of the accident scene and the roll service condition, analysing the barrel fracture and sampling tests, proved that main cause for the roll breakdown was unusual and there appeared a strip-like crack on the boundary layer resulting from the initial flaws extending along the roll circle direction; furthermore, the flaws caused fatigue breakage along the roll inner cross section, which resulted in the barrel breakdown.

Study on Wear-Resistance of Laser Surface Remelted-Strengthening High NiCr Indefinite Chilled Iron Roll Material

Rolling friction and abrasion test of high NiCr indefinite chilled iron roll material was developed on Arms Abrasion Tester made in Japan. The results showed that among two groups of samples with laser surface remelted-strengthening, C2 group samples of higher laser power and quicker linear speed had higher wear-resistance, and №6 sample of C2 group has the best with 1.5 mm beam diameter, 240-250W power and 30 mm/s linear speed, its total wear extent of three work conditions was only 16.3mg, and its wear-resistance increased 34.8% compared with №3 sample which had the best wear-resistance in C1 group without laser surface remelted-strengthening,; and for contrast of average wear-resistance of three work conditions, C2 group increased 49.3% compared with C1 group, it was showed that the effect of laser surface remelted-strengthening on high NiCr indefinite chilled iron roll material were very evident.

Study on Structure and Properties of Alloy Nodular Cast Iron Roller with Laser Heat Treatment

The microstructure analysis and hardness test were carried out on the surface of alloy nodular cast iron roll treated with CO2 laser of power 5 KW by optical microscopy, Rockwell hardometer and micro-hardometer. The results indicate the cladded layers with laser heat treatment are divided into melt region, phase change region and substrate region. The dimension and microhardness for every region are related to laser power, scanning speed and process parameters. The fatigue life of alloy nodular cast iron roll treated with laser increased remarkably.