| Perforation completion that is widely used at home and abroad is a method of well completion. Perforation is an most important technic in the course of oil prospecting, which is also a way to raise the recovery efficiency of well. Perforating gun that import entirely at one time is used for fixed the direction of perforation in performation operation, and protect the casing in explosion. Its demand on size, properties and surface is severe.According to the needs of project, design and empolder a new kind of steel CrMo-114 using for perforating gun in this paper. That is add micro-alloy elements to Cr-Mo low-carbon steel such as Nb, V, Ti and so on. Make contents of elements in the steel meet the demand of design by pick charging, control the procedure rigorously which include EAF, LF, HCC and VD, than the tube blank has been rolled toΦ114.3 mm×8.31 mm pipe. Draw CCT graph of CrMo-114 steel by dilatometer method to make sure the rationality of heat treatment. In the light of the temperature of phase transition, choose 880℃ 960℃as heating temperature and hold for 30 min or 60 min in quenching, and high tempering at 580℃ 640℃immediately. Characterize microscopic structure, composition of phases and impurities by OM, SEM, TEM. Investigate the effects of structure at strength, rigidity and toughness by tensile test, longitudinal and lateral impact test.The results indicate that the microstructure of CrMo-114 steel is Bainite as rolled. After quenching it transform Martensite lath, which is 510μm long and 0.51.5μm wide, the grain size of the steel is more than 7 as well. The higher the quenching temperature the more coarsing the structure, which is same with the increase of holding time. But the effects of heating temperature is prominenter, when quench at 920℃or above the grain grow up observably. It can be seen that structure of Martensite lath in which is consisted of high density dislocation cell is parallel by TEM, and there are retained austenite films that is banded on the edge of lath. After high temperature tempering the microstructure transform into tempered Sorbite. With the rise of temper temperature ,Ferrite become isometric and granular Cementite gather and develop. There are precipitates which is quadrate, granular, axiolitic and irregularly shaped. By indicate the SAEDP, the results show that the precipitates are TiN, V(C,N), TiC and (Ti,Nb)CN.It appear plastic deformation before CrMo-114 steel frature, which agree with the results of impact toughness test. Microporous gathering model ductile fracture is primary fracture mechanics of the steel, and intergranular fracture happen partially. It has been seen that there are a few globular and axiolitic impurities which improve the toughness by Calcium treatment in Steel-Smelting progress on the fracture surface at the same time. The main impurities are composite sulfide (Mn, Fe)S and SiO2,Al2O3,MnO and CaO which are compound together by analyzing EDS.The higher temper temperature, the better toughness of the steel, but the strength is decreasing. It is shown that the optimum combination of strength and toughness can be expected of the steel tempered at 640℃. Combine with the change of structure in different heat treatment conditions, the optimum technology of the steel is quenching in water after heat the sample up to 920℃and hold 30 min, tempering at 640℃for 60 min and air cooling immediately. By the progress above, precipitates raise strength and fine structure ensure toughness result to high comprehensive mechanical property. The yield strength reach 1059Mpa, yield to tensile strength ratio is more than 0.9, longitudinal and latitudinal charpy impacting energy absorption is 120 J and 80 J, the fracture appearance transition temperature of the steel is low to -33℃as well, which meet technique data.
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