Influence of band microstructure on carbide precipitation behavior and toughness of 1 GPa-grade ultra-heavy gauge low-alloy steel

This study investigated the influence of band microstructure induced by centerline segregation on carbide precipitation behavior and toughness in an 80 mm-thick 1 GPa low-carbon low-alloy steel plate.The quarter-thickness(1/4t)and half-thickness(1/2t)regions of the plate exhibited similar ductility and toughness after quenching.After tempering,the 1/4t region exhibited~50%and~25%enhancements in both the total elongation and low-temperature toughness at-40°C,respectively,without a decrease in yield strength,whereas the toughness of the 1/2t region decreased by~46%.After quenching,both the 1/4t and 1/2t regions exhibited lower bainite and lath martensite concentrations,but only the 1/2t region exhibited microstructure bands.Moreover,the tempered 1/4t region featured uniformly dispersed short rod-like M_(23)C_(6)carbides,and spherical MC precipitates with diameters of~20–100 nm and<20 nm,respectively.The uniformly dispersed nanosized M_(23)C_(6)carbides and MC precipitates contributed to the balance of high strength and high toughness.The band microstructure of the tempered 1/2t region featured a high density of large needle-like M3C carbides.The length and width of the large M3C carbides were~200–500 nm and~20–50 nm,respectively.Fractography analysis revealed that the high density of large carbides led to delamination cleavage fracture,which significantly deteriorated toughness.

Heavy Charged Gauge Bosons with General CP Violating Couplings

Heavy gauge bosons such as W＇ are expected to exist in many extensions of the Standard Model. In this paper, the most general Lagrangian for the interaction of W＇ with top and bottom quarks is considered. This Lagrangian consists of V- A and V ＋ A structure with in general complex couplings. Such interactions produce an Electric Dipole Moment （EDM） for the top quark at one loop level. We predict the allowed ranges for the mass and couplings of W＇ by using the upper limit on the top quark EDM.

Recent developments of large diameter X80 UOE line pipes

High-strength pipeline steel and large diameter line pipes are often used to increase the capacity of transportation and reduce the cost associated with the construction and operation of long-distance gas pipeline projects. China＇ s initiatives to construct long-distance natural gas pipelines has brought in new opportunities for the development of X80 line pipes. Baosteel has designed the optimum chemical composition of X80 with high niobium and low molybdenum content. In addition, a welding experimental platform and a finite element model （FEM） have supported the development of X80 UOE pipes in an efficient and economical way. The application and recent development of X80 UOE pipes were introduced in this paper. To comply with the requirements of the Second West-East Gas Pipeline Project （2^nd WEPP ）, X80 pipeline steel with low carbon bainite microstructure was developed by utilizing the optimized composition and TMCP process. The matching welding material, welding procedure and UOE forming processes for 1 219mm outside diameter X80 UOE pipes were also developed. More than 340 000 t of X80 UOE pipes were produced and applied in the 2^nd WEPP. Furthermore, to meet the prospective demand for long-distance gas pipelines with an annual transportation capacity of over 40 billion m3 ,larger size X80 UOE pipes with 1 422 mm OD × 30. 8 mm WT were trial produced recently. DWTT performance, the main technical challenge for heavier wall pipes, was improved by using optimized microstructural design. The newly developed X80 pipes can be potentially used for larger transportation capacity pipelines in China.

Search for dark matter production in association with the Z′ boson at the LHC in pp collisions at √s=8 TeV using Monte Carlo simulations

This analysis evaluates the possibility of the search for Dark Matter(DM)particles using events with a Zf heavy gauge boson and a large missing transverse momentum at the Large Hadron Collider(LHC).We consider the muonic decay of Z'.The analyzed Monte Carlo samples were the Open simulated files produced by the Compact Muon Solenoid(CMS)collaboration for proton-proton collisions,corresponding to an integrated luminosity of the LHC run-I with 19.7 fb^(-1) at √s=8 TeV.Two scenarios,namely a simplified benchmark scenario,called Dark Higgs,and the effective field theory(EFT)formalism,were used for interpretations.Limits were set on Z′,dark matter masses,and the cutoff scale of the EFT.

Search for W' signal in single top quark production at the LHC

Heavy charged gauge bosons are proposed in some theories beyond the standard model. We explore the discovery potential for W＇→tb with top quark semi-leptonic decay at the LHC. We concentrate on the new physics signal search with the deviation from the standard model prediction if the resonance peak of W＇ cannot be observed directly. Signal events with two jets plus one charged lepton and missing energy are simulated, together with the dominant standard model backgrounds. In this paper, it is found that suitable cuts on the kinematic observables can effectively suppress the standard model backgrounds mass is less than 6.6 TeV. so that it is possible to search for a W＇ signal at the LHC if its