The main points of the trial production process are the smelting and pouring process. The main points of the process are: the solution pool is cleaned and added at 0.90%; the high temperature (1580e) decarburization during the oxidation period is not less than 0.30%, so as to fully degas and remove the inclusion; pre-deoxidation insert Al0.5kgPt, It is reduced by C powder white slag method, and the composition before tapping is adjusted C0. Macroscopic coarse-grained 20Cr1Mo1VNbTiB forging material often finds coarse crystal phenomenon, the main reason is that the forging material is increased in fire times and the processing temperature is too high. This rolled material uses a fired material to eliminate the macroscopic coarse crystal phenomenon. Analysis of the causes of cracking of steel After the 9 steel ingots were formed, the cracks were as deep as 20 mm. There was only one crack in each ingot. Through the metallographic observation, the crack tip was not expanded and passivated, and the crack tip decarburization depth was 011 mm. In addition, some red steel ingots were found to have cracks in the middle of one side before rolling. These phenomena indicate that the cracking of the steel is caused by the longitudinal cracking of the steel ingot. As for the longitudinal cracking of the steel ingot, it is caused by improper annealing or excessive heating of the soaking heat, which needs further analysis. The effect of tempering temperature on the performance index of Rb, Rs, D5, W and so on. Rb and Rs increase with the increase of temperature in the range of 400600e, and decrease significantly with the increase of tempering temperature after 600e. D5 is relatively stable (1415%) in the range of 400650e, and 650750e increases significantly with the increase of temperature. ,W slowly rises as the temperature rises. Temperature (0e) The effect of tempering temperature on performance is tempered below 400e, and as tempering temperature increases, Rb, Rs decrease and D5 increases. 300e tempered metallographic organization. The decrease in strength is mainly due to a sharp decrease in internal stress. 1020e oil-cooled +300e@6h air-cooled tempering structure, 200@Rb, Rs increased in the range of 400600e with the increase of fire temperature, mainly caused by tempering secondary hardening of Cr, Mo, Nb and other elements. The main cause of secondary hardening is that during the tempering process, the alloy carbide is formed independently on the dislocation line of the martensite crystal at the specific temperature, precipitates in a dispersed form and maintains a coherent relationship with the parent phase, thus hardness. Reach the peak. According to the data <4>, the tempering of molybdenum-containing steel above 500e will show significant secondary hardening, the secondary hardening effect of vanadium is significant, and the peak of 600e tempering after 5 hours. It can be seen that the 400600e tempering Rs and Rb increase with the increase of temperature, which is mainly caused by the secondary hardening of elements such as Mo, V and Nb. The metallurgical structure of the 550e tempered for 6 hours, visible from the 550e tempered alloy carbides were clearly precipitated. 1020e oil-cooled +550e@6h air-cooled tempering structure, 200@1020e oil-cooled +700e@6h air-cooled tempered structure, 200@ tempered above 600e, with the increase of tempering temperature, the granular carbide further aggregates and grows, at the same time The needle-like morphology of ferrite disappears, and the microstructure-like carbides are distributed on the basis of polygonal massive ferrite, ie, tempered sorbite, which has good strength, plasticity, elasticity and toughness. Comprehensive mechanical properties. After 700e tempered for 6 hours, the visible shape of the needle-shaped ferrite disappeared and the carbides grew up. Supply status (annealing) organization, 200@400650e tempering, D5 is more stable, but in the qualified edge of technical specifications. Therefore, the comprehensive strength and plasticity requirements, the tempering temperature is about 700e is ideal. Conclusion. The trial steel can meet the requirements of technical specifications. The sample heat treatment adopts 1020e oil cooling +700720e@46h air cooling, and its comprehensive performance index is the most ideal. The main reason for the low Nb recovery rate is that Nb)Fe contains too high a Nb, which causes its melting point to be too high to be melted. The key to B recycling is how to degas and deoxidize before adding B. Copper Nickel Alloys,CuNi Resistance Alloys Wire,CuNi Resistance Alloy Strip Alloys Aluminum Pipe/Tube Co.,Ltd , http://www.nsmetalproduct.com
Development of bolt-frame structure equipment for chromium-containing molybdenum, nickel and titanium alloys