Laboratory Development Of1500MPa Grade Super-strength Low Alloy Steel

This article introduced laboratory development condition of1500MPa grade super-strength low alloy steel, the target of this subject is to develop a steel, its tensile strength abtain1500MPa,matched quality ductility and combination property. In order to abtain this target, First used conventional technology to develop this steel, i.e. off-line quenching and low temperature tempering after hot rolling, based on this technology gain success,further studied on use direct quenching to develop this steel,direct quenching technology is more energy conservation and shorten production cycle. Main content of this article as following:1. Analysed compositional character of super-strength low alloy steel at home and abroad, analysed action of various element in steel, determined composition series of this steel, according to target strength grade, designed chemical composition of this steel,and smelted experimental steel.2. Measured thermal plasticity and heat resistance curve at Gleeble3800thermal simulation testing machine, use thermal expansion method measured transformation point and CCT curve at Formastor-D full automaticity phase change machine, calculated liquid line temperature, measured hardenability, laid the foundation for working out steel making, rolling, heat treatment and direct quenching parameter.3. Use the method of orthogonal experimental design, determined optimal quenching and low temperature tempering technology of1500MPa grade super-strength low alloy steel, checked mechanical property, metallurgical structure and austenitic grain size after heat treatment, proved the composition design is right,matched post suitable rolling, quenching and low temperature tempering, strength of steel can abtain target,and have perfect metallurgical structure and combination property;4. Use direct quenching developed1500MPa grade super-strength low alloy steel, adopt high temperature,slow rolling speed, strong compression ratio, finish rolling at austenitic recrystallization zone or unrecrystallization high temperature zone, quick cooling after rolling, and control different interrupted quenching temperature of steel plate. Studied combination property of different interrupted quenching temperature steel plate, determined optimal interrupted quenching temperature,at the same time, proved the rolling and cooling technological desigh is right, matched post suitable interrupted quenching temperature, the steel plate can effective utilize excess heat to temper, abtain perfect metallurgical structure, and mechanical property can abtain or exceed the quenching and low temperature tempering steel plate.