Microstructure, Properties and Heat Treatment Process of Powder Metallurgy Superalloy FGH95

 Microstructure and properties of nickel based powder metallurgy (PM) superalloy were presented. Effects of nonmetallic inclusions and heat treatment on microstructure and properties were discussed. Development tendency of microstructure and properties of PM superalloy was presented.     

Effect of Additives on Melting Point of LATS Refining Ladle Slag

  To avoid slag sticking on the ladle immersion cover during the LATS refining and alloying process, the effect of Al2O3 on the melting point of the ladle slag was studied and the additives including CaF2, B2O3, Li2O, and CaO were used to decrease the melting point of the ladle slag. The melting point was measured using the hemisphere method. The results show that the addition of Al2O3 to the ladle slag increases the melting point. The fluxing action is not remarkable if only CaF2 or CaO is used as the additive. The fluxing action of the composite additive obtained by the mixing of CaO and CaF2 in the mass proportion of wCaO∶wCaF2=2∶1 is preferred. The fluxing action of B2O3 is also notable. When the B2O3 content in mass percent is in the range from 2% to 10%, the corresponding melting point is 1 380 ℃ to 1 290 ℃. The fluxing action of Li2O is the most remarkable. When the Li2O content is up to 5%, the melting point of the slag is lower than 1 300 ℃.     

Calculation of AlN and MnS Precipitation in NonOriented Electrical Steel Produced by CSP Process

Combining with the study of analogue experiments and test analysis, the kinetics of precipitation and growth of AlN and MnS in nonoriented electrical steel produced by the CSP process is calculated. The results show that the precipitate phase particles of AlN and MnS in typical nonoriented electrical steel grades produced by the CSP process have grown to some extent in the soaking stage, but the precipitation contents are less than 20% of the total contents of nitride and sulfide. The precipitate phase particles of AlN and MnS have precipitated almost after the hot rolling process. The precipitation contents are more than 80% of the total contents of nitride and sulfide, but it is very late for the precipitate phase particles to grow at the end of the hot rolling process.     

Process Simulation and Microstructure Analysis of Low Carbon SiMn Quenched and Partitioned Steel

The quenching and partitioning (Q&P) process was experimentally investigated on the thermomechanical simulator (Gleeble3800). The microstructure and fracture mechanism of the sheets were investigated by means of TEM. It was found that the microstructure of quenched and partitioned steel consists of fine lath martensite and thin interlath austenite films. The optimum quenching temperature of producing the maximum amount of retained austenite after final quenching at room temperature was predicted by Matlab software package. It was found that the calculations by Matlab software can provide guidance for experimental processing design reliably. The volume fraction of retained austenite at room temperature was approximately 8%, which was measured easily by the software VC60++ programming. The results verified that quenched and partitioned steel possesses a good combination of strength and plasticity due to its fine microstructure. This steel exhibited high ultimate tensile strength (exceeding 1 000 MPa) and good elongation of 25%. The results showed that the fracture mechanism of the sheets is typical tough fracture under the condition of tensile failure.     

Industrial Experiment of Reducing Superheat of Steel by Nozzle Cooling

 Nozzle cooling equipment is developed to supervise and control the heat flux by changing water flux. An industrial experiment is held in billet caster in Huaigang . The results show that cooling control system works stably and effectively to control the heat fluxes by the temperature of copper tube. The superheat of steel in mould is reduced and the equiaxed crystal ratio, as well as compact degree of steel is raised.     

Corrosion behavior of NiCr alloys in HCl-containing oxidation atmosphere at 700-800℃

Corrosion behaviors of pure Ni and three NiCr alloys were investigated in an HCl-containing oxidizing at-mosphere at 700℃ and 800℃. All materials suffer from accelerated corrosion at both temperatures. NiCr alloys show an initial mass loss due to the formation of volatile CrCl3 and CrO2Cl2. Some chlorides are detected at the scale/substrate interface and many voids are also found there. NiCr alloys with higher chromium content have better corrosion resistance. However, Ni50Cr is inferior to Ni25Cr due to its two-phase structure, which makes it easy for chlorine to diffuse along grain boundary and to occur inner oxidation. The relevant corrosion mechanism was also discussed.     

Numerical Simulation of Linear Electromagnetic Stirring in Secondary Cooling Region of Slab Caster

SymbolList　　B———Magneticfluxdensity ,T ;　　B ———ConjugatedcomplexnumberofB ,T ;　　Bc———Magneticfluxdensityinboundaryproducedbycoilcurrent,T ;　　Bi———Magneticfluxdensityinboundaryproducedbyin nerinductioncurrent ,T ;　　F———Electromagneticforce ,N·m- 3;　　g———Gravitationalacceleration ,m·s- 2 ;　　I———Coilcurrent ,A ;　　j———Symbolusedcommonlyinelectricalnotation(=- 1) ;　　J———Inductioncurrentdensity ,A·m- 2 ;　　k———Turbulencekineticenergy ,m2·…