Linear Contraction Behavior of Low-Carbon, Low-Alloy Steels During and After Solidification Using Real-Time Measurements

A technique for measuring the linear contraction during and after solidification of low-alloy steel was developed and used for examination of two commercial low-carbon and low-alloy steel grades. The effects of several experimental parameters on the contraction were studied. The solidification contraction behavior was described using the concept of rigidity in a solidifying alloy, evolution of the solid fraction, and the microstructure development during solidification. A correlation between the linear contraction properties in the solidification range and the hot crack susceptibility was proposed and used for the estimation of hot cracking susceptibility for two studied alloys and verified with the real casting practice. The technique allows estimation of the contraction coefficient of commercial steels in a wide range of temperatures and could be helpful for computer simulation and process optimization during continuous casting. © 2013 The Minerals, Metals & Materials Society and ASM International

The Role of Austenite Grain Misorientation on on Ferrite Nucleation in an Fe-Cr-Ni Alloy

A

The role of alpha/gamma orientation relationships during ferrite nucleation in an Fe-Cr-Ni alloy

The role of the alpha/gamma orientation relationships during ferrite nucleation is investigated. EBSD measurements were performed on an especially developed high purity ternary iron-based alloy with 20 wt.% Cr and 12 wt.% Ni with both austenite and ferrite present at room temperature to measure the orientation relationship between the austenite and ferrite crystallites. The experimental results are compared to the nucleation models of Clemm and Fisher and Aaronson and co-workers

Impact of neutron irradiation on the strength and ductility of pure and ZrC reinforced tungsten grades

The strength and ductility of two tungsten products, developed for application in nuclear fusion environment,are studied before and after neutron irradiation using uniaxial tensile tests. The first product is a commercially pure tungsten, produced by AT&M company according to ITER specification, and the second one is reinforced with zirconium carbide (WeZrC) particles. The addition of ZrC particles leads to a reduction of the ductile to brittle transition temperature (DBTT) in non-irradiated conditions down to 50-100 °C without loss of strength and of other attractive properties of tungsten. The neutron irradiation was performed in the range 625-700 °C up to 1.125 dpa. The tests were performed to screen the shift of the DBTT as well as to characterize the evolution of the strength and ductility at the irradiation temperature. In addition, a series of interrupted tensile tests were performed in order to determine the variation of the yield strength as a function of temperature using an original single specimen test method. The neutron irradiation causes the reduction of the total elongation of both tungsten products. The DBTT range, which was evaluated from the tensile test results, of W-ZrC lies in the 300-500 °C range (while it is ~100 °C in non-irradiated state). The DBTT range of pure tungsten is between 400 and 575 °C i.e. higher than that of W-ZrC. The irradiation hardening, measured at ~600 °C, which is close to the irradiation temperature, leads to an increase of the proof stress by a factor of two in both studied grades. Despite that the irradiation induced hardening, both products retain a total elongation of about 10% prior to fracture. W-ZrC exhibits a similar total elongation at 500 °C, thus maintaining a significant ductility resource, while pure W becomes brittle at 500 °C and below