Dissertation
Dissertation > Industrial Technology > Metallurgy and Metal Craft > Metal pressure processing > Rolling > Rolling mill machinery equipment > Bodies and equipment of the mill primary columns > Roller and roller bearings

Reseach on Wear Resistance and Contact Fatigue Performance of Alloy Cast Steel for Roller

Author ZhaoShuFeng
Tutor LiGuoLu
School Hebei University of Technology
Course Materials Processing Engineering
Keywords alloy cast steel roller microstructure heat treatment process wear-resisting property contact fatigue property thermal fatigue property
CLC TG333.17
Type Master's thesis
Year 2011
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Roller of modern production is prone to occurring failure form of fatigue wear (mainly peeling off and roll breakage).Therefore, this paper designs two types of materials for alloy cast steel roller, including Cr alloy cast steel roller and bainite-based alloy cast steel roller. Based on the improving and optimizing of the roller material, research on wear resistance,contact fatigue performance and thermal fatigue properties of two types of materials for alloy cast steel roller were carried out to determine the best sample composition and heat treatment process while roller performance was improved at the same time. Meanwhile, the cast steel roller material resources were enriched to provide technical reserve for meeting different customer and rolling condition and give direction for the development of new roller materials.Results of this study showed that:(1) By studying on wear and contact fatigue performance of No.2 and No.4 specimens Cr alloy cast steel roller, it can be concluded that the wear performance is best when heat treatment of No.4 specimens is austenitizing temperature 1100℃for holding time 50 minutes and oil quenching, tempering temperature 520℃for holding time 75 minutes and air cooling, while the contact fatigue performance is best when heat treatment of No.2 specimen is austenitizing temperature 960℃for holding time 50 minutes and oil quenching, tempering temperature 520℃for holding time 75 minutes and air cooling, the eigen life is 1.8370×106 cycles. (2) By studying on wear and contact fatigue performance of No.6 and No.8 specimens, it can be concluded that weight loss of grinding is minimum and wear performance is the best when heat treatment of No.6 specimen is austenitizing temperature at 900℃for 1.0 hour, and then austempering temperature at 320℃for 1.0 hour, thirdly tempering temperature at 250℃for 2.5 hours and air cooling while contact fatigue performance is the best when heat treatment of No.8 specimen is firstly austenitizing temperature at 900℃for 75 minutes, secondly austempering temperature at 320℃for 1.0 hour, thirdly tempering temperature at 250℃for 2.5 hours and air cooling, the eigen life is 1.3075×106 cycles. (3) Through these two types of materials for alloy cast steel roller of thermal fatigue properties obtained:Cr Series roll material has better thermal fatigue properties. No.2 specimen which Cr content of 5% and heat treatment process is austenitizing temperature 960℃for holding time 50 minutes and oil quenching, tempering temperature 520℃for holding time 75 minutes and air cooling has the best thermal fatigue properties. The thermal fatigue properties declined when Cr increased to 8%. In bainite-based alloy cast steel roll,when heat treatment process of No.8 specimen is firstly austenitizing temperature at 900℃for 75 minutes, secondly austempering temperature at 320℃for 1.0 hour, thirdly tempering temperature at 250℃for 2.5 hours and air cooling, thermal fatigue properties is the best.The best chemical composition and heat treatment of the performance through the experimental research and theoretical analysis were: (1) The proper chemical composition and heat treatment process of the wear performance were: carbon 1.118%, silicon 0.686%, manganese 0.661%, chromium 7.981%, molybdenum 0.529%, nickel 0.415%, vanadium 0.150%. The best heat treatment processes were: austenitizing temperature 1100℃for holding time 50 minutes and oil quenching, tempering temperature 520℃for holding time 75 minutes and air cooling. (2) The proper chemical composition and heat treatment process of the contact fatigue and thermal fatigue properties were:carbon:0.537%,silicon:0.662%,manganese:0.671%, chromium:4.74%,molybdenum:0.458%,nickel:0.338%,vanadium:0.129%. The best heat treatment processes were: austenitizing temperature 960℃for holding time 50 minutes and oil quenching, tempering temperature 520℃for holding time 75 minutes and air cooling.

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