| At present,most of hammer crushers are used in mines and other industries.Hammer head is one of the important wear parts.With the development of technology and market demand,the types and types of hammer crushers are increasing,and the single material and single-size hammerhead can’t satisfy the requirements of various crushers.The diversity of dimensions leads to complex manufacturing processes and increased production costs.This paper presents a two-fluid metal composite casting/welding combined wear-resistant hammerhead,and systematically studies the material composition,manufacturing process,and wear resistance.The hammer end of the hammer is a double liquid metal composite material,and the hammer handle is a low alloy steel material,and at the same time,the wear resistance and the toughness of the hammer head are ensured.The hammer end and the hammer handle are connected by welding,and can be adjusted in size by relative positions to satisfy the use of most machines.The life of the hammer is improved,the replacement cycle is reduced,the production efficiency is improved,and the economic loss can be reduced,which has important practical significance.In this paper,the composition design and heat treatment process of hammer-end high-chromium cast iron were studied.The effects of carbon content change and austenitizing temperature on the microstructure and wear resistance were investigated and analyzed theoretically to determine the optimal distribution ratio and heat treatment.The process completes the preparation of the two-fluid metal sample.Through microstructure and energy spectrum analysis,the interface and element diffusion at different pouring temperatures were observed.The CO2 gas shielded welding technique was used to reconnect the two-fluid composite hammer ends with the low alloy steel hammer shanks to determine the welding parameters.The effect of the thickness of the different welding layers and the middle of the hammer end on the interface microstructure and properties was investigated.Studies have shown that as the carbon content increases,the number of carbides increases and the hardness increases,but the toughness rises to a maximum,and finally cracks appear on the casting surface,resulting in the failure of the casting.When the carbon content was 3.6wt.%and 3.8wt.%,the penetration crack appeared on the surface of the sample,and the comprehensive mechanical properties were the best at 3.4wt.%.After 1000℃×2h+air cooling,the Rockwell hardness was more than 64HRC and the impact toughness value was 5.5J/cm2;In the process of double-liquid bimetal recombination,the pouring temperature is a crucial step.If the temperature control is not good,there will be corresponding defects.The higher the casting temperature of the high-chromium cast iron,the wider the remelting range of the low-alloy steel,resulting in compounding When the defect occurs,the remelted area of the low-alloy steel is relatively narrow,the compounding is difficult,and the interface strength is low when the pouring temperature is low.From the observation of the microstructure,when the pouring temperature is 1540℃,the composite interface shows a small saw-toothed shape.The interface has no flushing phenomenon,the organization is dense,and the bonding state is ideal;Through the penetration test of the weld,no defects such as cracks and pores have been found.As the distance from the weld is getting farther away,the microhardness gradually increases.When the weld is far away from the weld,the temperature decreases and the microstructure changes relatively.Obviously,therefore,the microhardness value increases,and when the bimetallic interface and the high chromium cast iron are reached,the microhardness is slightly lower than that of the unwelded bimetal specimen.As the thickness of the steel layer increases,the microhardness gradually increases,the thickness increases,the more heat is absorbed,and the more uniform the heat distribution,in contrast,the tissue changes are relatively small.The final hammer-end high-chromium cast iron contains 3.3wt.%3.5wt.%carbon,casts1540℃,and has a steel layer thickness of 10mm15mm.When welding,two layers of multi-pass welding methods are used;then 1000℃×2h+wind quenching heat treatment is performed.The final hammer hardness is above 64HRC and the impact toughness is 5.5J/cm2.Hammerheads produced using this technology can be mass-produced,meeting the needs of most hammer crushers,reducing replacement cycles and increasing production efficiency. |
