Effect of quenching and tempering processes on properties and microstructure of G115 steel

The novel martensitic heat-resistant steel G115 was designed for thick-section boiler components of ultra-supercritical(USC) power plants at 630-650 ℃.The impact of the quenching and tempering processes on the properties and microstructure of G115 steel was explored.The samples that were quenched and tempered twice had a higher tensile strength at room temperature and 650 ℃,and the impact energy was significantly improved.The strength and impact energy increased in proportion to the increase in the first quenching temperature.The microstructure differences between the single and double quenched and tempered samples were examined using metallographic microscopy and scanning electron microscopy.The grain size of the double quenched and tempered samples was finer than that of the single quenched and tempered samples, and the tempered martensite lath is more visible, as are the carbides and other precipitates, which are finer and more uniformly distributed.As the first quenching temperature increased, the grains became coarser but more uniform.

Numerical simulation research of dimension variation in heavy plate during quenching and tempering process

The dimension variation of B610E steel during the quenching and tempering process was simulated by ABAQUS,the coefficient of heat transfer during quenching was verified by the buried thermocouple test and the trend of the dimension variation during the quenching process was also calculated by ABAQUS. It was shown by the comparison of simulated results and industrially measured results that only the simulation of thickness and width variation was accurate, while length variation needed further simulation. Besides, the dimension variation trend was identical with the measured results.

Study on Quenching and Tempering Process of Q960 High Strength Steel for Construction Machinery

To develop the Q960 high-strength quenched and tempered steel plates for construction machinery,the effects of quenching and tempering treating regime on the microstructures and mechanical properties were investigated.The results show that the perfect austenization and fine grain size can be achieved by the optimum quenching process that is quenching temperature 900℃ and holding time 20min.Considering performance and production efficiency,the optimum tempering process parameters are found that tempering temperature 600℃ and holding time 40min.The excellent overall properties of specimens with tempered sorbite microstructure can be ultimately obtained.The yield strength is 1030MPa,tensile strength 1080MPa,percentage elongation 16.8% and the Charpy impact energy 144J at-40℃.All these indexes come up to the National Standard GB/T 16270-2009.

Comparison of Microstructures and Properties Obtained After Different Heat Treatment Strategies of High Strength Low Alloyed Steel

The influence of different heat treatment strategies on the microstructure and properties of 42SiCr steel was investigated.To compare the benefit of innovative treatment methods with more conventional ones,several strategies based on a new quenching and partitioning (Q-P) process were designed together with several strategies using more traditional quenching and tempering process.Different combinations of mechanical properties were obtained with ultimate strengths in the range of 1818-2120 MPa and ductility between 10% and 24%.Resulting microstructures were martensitic with 0-12% of retained austenite and they were analyzed by laser scanning confocal microscopy,transmission electron microscopy and X-ray diffraction phase analysis.

Application of the Computer-aided Quenching Technology on the Connecting Bar of 42CrMo4

In order to obtain the desired mechanical properties of connecting bar after quenching and tempering,and reduce the cracking tendency and distortion,a program of controllable quenching was established.Furthermore,a computer-aided quenching (CAQ) system was developed.The applications show satisfactory results.