Production practice of drillable ASTM4140 steel for tube blank
To introduce production practice of drillable ASTM4140 steel for tube blank.Using 42CrMo scrap steel and w(P)≤0.15％,w(S)≤0.40％molten iron,final slag alkalinity is controlled 3.5～4.5 for electric furnace smelting,re-fining control white slag time no less than 55 min,by maintaining vacuum for long time and fully soft blowing after breaking air to reduce possibility of producing large number of oxidizing inclinations,induction quenching and high temperature tem-pering process after annealing is carried out.Through production process control,average end point of electric furnace C,P composition and temperature fluctuations are small,gas content in liquid steel after VD furnace vacuum is very low,purity of molten steel is high,low power test results are central loose grade one,general loose grade one,no subdermic bubbles and cracks,after annealing steel under 880 ℃ induction quenching and 680 ℃ tempering performance is excellent.The o-verall Rockwell hardness of cross section is 23～30 HRC,hardness of center is 23～25 HRC,which is in line with design expectation.
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