Erosion resistance of Fe-C-Cr weld surfacing layers

Fe C Cr weld surfacing layers with different compositions and microstructures can be obtained by submerged arc welding with welding wire of the low carbon steel and high alloy bonded flux. With the increase of Cr and C in the layers the microstructures are changed from hypoeutectoid steel, hypereutectoid steel to hypoeutectic iron and hypereutectic iron. When the weld surfacing layers belong to the alloyed cast irons the erosion resistance can be raised with the eutectic increase and the austenite decrease. Good erosion resistance can be obtained when the proportion of the primary carbides is within 10 %. The experimental results lay a foundation to make double metal percussive plates by surfacing wear resistant layers on the substrates of the low carbon steels.

Progress in research on diffusional phase transformations of Fe–C alloys under high magnetic fields

The solid-phase transformations of metal materials under high magnetic fields are an important topic in research on the electromagnetic processing of materials.Progress in research on the diffusional phase transformations of Fe–C alloys under high magnetic fields is reviewed.The effects of high magnetic fields on the microstructural evolution in diffusional phase transformations in Fe–C alloys are discussed.The kinetics of ferrite transformations,pearlite transformations,and the precipitation of carbides under high magnetic fields are reviewed in terms of the thermodynamics of phase transformations and the diffusion behavior of carbon atoms.Finally,future trends in research on diffusional phase transformations of Fe–C alloys under high magnetic fields are discussed.

Phase-field simulation of tip splitting in dendritic growth of Fe-C alloy

Two types of dendrite tip splitting including dendrite orientation transition and twinned-like dendrites in Fe-C alloys were investigated by phase-field method. In equiaxed growth, the possible dendrite growth directions and the effect of supersaturation on tip splitting were discussed; the dendrite orientation transition was observed, and it was found that the orientation regions of anisotropy parameters were reduced from three to two with increasing the supersaturation, which was due to the effect of interracial anisotropy controlled by the solute in front of S/L interface changing with the increase of supersaturation. In directional solidification, it was found that the twinned like dendrites were formed with the fixed anisotropy couples and no seaweed dendrites were observed; these were concluded from the results of competition between process anisotropy and inherent anisotropy. The formation process of twinned-like dendrite was investigated by tip splitting phenomenon, which was related to the chan ges of dendrite tips growth velocity. Then, the critical speed of tips splitting and solute concentration of twinned-like dendrites were investigated, and a new type of microsegregation in Fe-C alloys was proposed to supplement the dendrite growth theories.

Critical Cooling Rate for the Glass Formation of Ferromagnetic Fe_(80)P_(13)C_7 Alloy

In this paper the critical cooling rate, Rc, for the glass formation of Fe80P13C7 alloy has been determined using both Uhlmann＇s and Barandiaran-Colmenero＇s method. In Uhlmann＇s method, all kinds of the expres-sions of △G^l-s （T） and η/（T） determined using the different modes and methods had been investigated. It is indicated that the Rc for the glass formation of FesoP13C7 alloy can be estimated to be 349 K/s by Uhlmann＇s method based on the appropriate expressions of △G^l-s（T） and η/（T）. The calculated result accords with our experimental result. The Rc for the glass formation of Fe80P13C7 alloy has also been determined to be 0.49 K/s using Barandiaran-Colmenero＇s method. This resultant Rc is unreasonable low and it indicates that Barandiaran-Colmenero＇s method does not suit to Fe-based alloy.

钾、钠在铁碳铸造合金中作用机理的探讨

以试验研究为基础，着重分析了钾、钠在Ｆｅ—Ｃ合金中细化结晶组织，改善第二相形态及促进固、液态石墨化的作用机理，并对钾、钠在Ｆｅ—Ｃ合金中其它作用进行了简要讨论．