Research Of Corrosion-abrasion Resistant Alloy Steels For Semi-autogenous Mill Liner Plates

Liner plates of semi-autogenous mill grinding machine are under impact abrasive and serious corrosive wear condition.Nowadays high-manganese steel has been widely used as the SAG mill liner plates domestic and abroad,but the short life of high-manganese steel liner plates under abrasion made the production cost increase and this material must be displaced.In order to improve the service life and reduce production cost of SAG mill liner plates,the development of new wear resistant alloy steels has academic significance and economic value.In this context,a new type of high carbon low alloy steel has been developed and researched,at the same time a new bainite steel liner plates,a new high manganese steel composite liner plates,and a pearlite steel liner plates have been developed in cooperation with the factory.The effect of the heat treatment process on the chemical composition,microstructure,hardness,impact toughness,tensile test,corrosion resistance and impact corrosion abrasive wear resistance of the high carbon low alloy steel was researched with Leica metallographic microscope,muffle furnace,hardness tester,instrumented impact tester,tensile test machine,impact corrosion、abrasion testing machine,X-ray diffusion,scanning electron microscopy and other research instruments and means.At the same time,the microstructure and comprehensive properties of three new abrasion resistant liner plates were explored.Firstly,four different heat treatments were made for high carbon low alloy wear resistant steel with the composition of C0.65%,Si0.54%,Mn0.97%,Cr2.89%,Mo0.35%,Ni0.75%,N0.10%.The effect of heat treatment processes on high carbon low alloy’s microstructure and properties was discussed.The results show that the microstructure of high carbon low alloy steel annealed with being 1000℃ annealed,950℃ normalized and 250℃ tempered is pearlite,and its charpy V-notch impact absorption energy is highest(8.37 J).The elongation with the same heat treatment processes is maximum(14.31%),while the tensile strength,yield strength and hardness are 1005 MPa,850 MPa and 43.8 HRC.High carbon low alloy steel with being 1000℃ annealed,950℃ normalized and 250℃ tempered has the best comprehensive properties.The results of the study of the three new types of liner plates developed are as follows.The hardness of the bainite steel liner plates is 51.7 HRC.After working hardening,the liner plates’ hardness increases by 50 HV,and its charpy V-notch impact absorption energy is 7.50 J,whose hardness and toughness match well.High manganese steel matrix composite liner plates is a composite material with austenite as matrix and carbide as the second phase.The hardness of high manganese steel matrix composite liner plates is 26.5 HRC.After working hardening,the liner plates’ hardness increases to 667 HV(58.7 HRC),and its charpy U-notch impact absorption energy is 87.70 J.Elongation of the liner plates with good toughness is 9.20%,while the tensile strength and yield strength are 743 MPa and 547 MPa.The hardness of pearlitic liner plates is 31.3 HRC.After working hardening,the liner plates’ hardness is almost unchanged,and its charpy V-notch impact absorption energy is 6.00 J.Elongation of the pearlitic liner plates is low(6.64%),while the tensile strength and yield strength are 766 MPa and 420 MPa.In 4.5 J impact energy conditions: the worn loss weight of bainite steel liner plates is least,and this material have the best performance of impact corrosion abrasive wear resistance in this condition.In 9J impact energy conditions: the worn loss weight of high carbon low alloy steel annealed with being 1000℃ annealed,950℃ normalized and 250℃ tempered is least,and this material have the best performance of impact corrosion abrasive wear resistance in this condition.Analyses of the demand for apply conditions,when the impact load is very small,the SAG liner plates should made by the bainite steel.when the impact load is large,the SAG liner plates should made by the high carbon low alloy steel annealed with being 1000℃ annealed,950℃ normalized and 250℃ tempered.