Research and development of Q890D plate with a thickness of 130 mm
To solve the problem of difficult comprehensive production and poor properties of Q890D plates with a thickness of over 100 mm,a 130 mm thick gauge Q890D plate was developed through rational design of chemical composition,matching of clean steel smelting process,optimization of controlled rolling and controlled cooling,and quenching and tempering process.The test results show that the phase transformation temperature of the developed Q890D plate is Ac1=722 ℃,Ac3=869 ℃,Ms=424 ℃.When the cooling rate is higher than 10 ℃/s,the microstructure is fully martensitic.Within the quenching temperature range of 890-930 ℃,as the quenching temperature increases,the austenite grain size of Q890D plate coarsens,and its strength and ductility decrease.At a quenching temperature of 890 ℃,its original austenite grain size is 10.5 grade,and its comprehen-sive property is optimal.The 130 mm thick Q890D plate has achieved stable industrial production,with a yield strength of 892-927 MPa,a tensile strength of 974-1 015 MPa,an elongation of 13.0％-15.5％,an impact energy of 120-160 J at-20 ℃,and a Z-direction section shrinkage rate of 48％-62％.The internal ultrasonic testing of the plate has reached the quality level 1 in GB/T 2970-2016,and the all properties fully meet the requirements for supply and use.It has important reference signifi-cance for the development of thick ultra-high strength steel technology and industrial production.
Q890D heavy platechemical composite designprocess developmentmicrostructure and propertiesindustrial production
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