摘要:

AbstractAn investigation is reported of the constitution of the Ni rich portion of the Ni–Al–Mo–Ta system at 1273 and 1073 K. Alloys containing 85 and 75 at.-% Ni respectively were used for the investigation, their constitution at 1523 K having been previously determined. Electron probe microanalysis, X-ray diffraction, and light microscopy were the main techniques of examination. In the 85 at.-% Ni section of the system, only theγandγ′phases were present in the composition range extending up to 6 at.% Ta. In the 75 at.% Ni section, the following phases were encountered:γ,γ′,δ(based on Ni3Ta),η(based on Ni6TaAl),δ′(based on NiMo), and″(based on Ni3Mo). For the part of the section having Ta contents greater than about 10 at.-%, the equilibria involvingγγ′η,ηandδchanged little from at 1523 K. However, theγregion (based on Ni75Mo25)and theγ+γ′regions which existed at 1523 K were replaced by regions representing equilibria involving NiMo and Ni3Mo. A reactionγ+δ′⇛γ′+δ″is proposed between 1200 and 1073 K.MST/90

ISSN:0267-0836    

DOI:10.1179/mst.1985.1.1.61

出版商:Taylor&Francis    

年代:1985

数据来源: Taylor

摘要:

AbstractA survey is presented of the solidification characteristics, structure, and properties of theα–βdezincification-resistant brasses. Binary Cu–Zn and ternary Cu–Zn–Sn alloys have been examined, and the effects of single-element additions to a selected ternary alloy have been determined. A number of commercial brasses have been examined.MST/57

ISSN:0267-0836    

DOI:10.1179/mst.1985.1.1.73

出版商:Taylor&Francis    

年代:1985

数据来源: Taylor

摘要:

AbstractTransverse cracking in continuously cast microalloyed and low-alloyed steels has been shown to occur by a mechanism involving the formation of cavities at grain boundaries. Cavities are nucleated primarily at MnS and AIN particles. Crack formation by this mechanism can be minimized by encouraging stress relaxation away from grain boundaries and by avoiding the precipitation of sulphide and nitride particles on the grain boundaries. Gleeble testing has shown that the hot strength may be reduced and, therefore, the degree of stress relaxation improved, by minimizing alloying addition, particularly of Nb, V, and N in microalloyed steels and Cr, Ni, and Mo in low-alloy steels. Precipitation on grain boundaries may be reduced by additions of Ca and/or Ce or Ti and/or Zr, which cause the sulphides and nitrides, respectively, to precipitate in the liquid. Temperature cycling, particularly through theα–γtransformation, should also be avoided. The use of such measures has resulted in the production of C–Mn–Nb–Al slabs,>300 mm thick, which do not require any surface dressing before rolling.MST/51

ISSN:0267-0836    

DOI:10.1179/mst.1985.1.1.80

出版商:Taylor&Francis    

年代:1985

数据来源: Taylor

摘要:

AbstractThe fundamentals of the constitutive equations used for modelling the mechanical behaviour of metallic materials over wide temperature ranges are briefly reviewed. Examples of stress-calculation problems in cooling castings are given. Four constitutive relationships used for practical calculation of the stresses are analysed. An experimental assessment of their validity, based on a comparison of stress values predicted by the models with those obtained for ring-shaped, aluminium alloy castings with metallic cores, as well as with some published data concerning beam-shaped, low-carbon steel castings, is presented. It is concluded that the essential simplifications assumed in deriving the models lead to significant disagreements with experimental results in most of the investigated cases.MST/58

ISSN:0267-0836    

DOI:10.1179/mst.1985.1.1.84

出版商:Taylor&Francis    

年代:1985

数据来源: Taylor

ISSN:0267-0836    

DOI:10.1179/mst.1985.1.1.93

出版商:Taylor&Francis    

年代:1985

数据来源: Taylor