High strength bimetallic composite material fabricated by electroslag casting and characteristics of its composite interface

Bimetallic composite material of bainitic steel and PD3 steel was produced with electroslag casting process, and element distribution of its composite interface was investigated by theoretical calculation and energy dispersive spectrometer(EDS). Results show that the tensile strength(1,450 MPa), hardness(HRC 41-47) and impact toughness(94.7J·cm^(-2)) of bainitic steel were comparatively high, while its elongation was slightly low(4.0%). Tensile strength(1,100 MPa), hardness(>HRC 31) and elongation(7.72%) of the interface were also relatively high, but its impact toughness was low at 20.4 J·cm^(-2). Results of theoretical calculation of the element distribution in the interface region were basically consistent with that of EDS. Therefore, electroslag casting is a practical process to produce bimetallic composite material of bainitic steel and PD3 steel, and theoretical calculation also is a feasible method to study element distribution of their interface.

Behavior of Non-metallic Inclusions in Centrifugal Induction Electroslag Castings

In order to know the behavior of non-metallic inclusions in centrifugal induction electroslag castings (CIESC), non-metallic inclusions in 5CrMnMo and 4Cr5MoSiV1 were qualitatively and quantitatively analyzed. The largest size of inclusions in the casting and the thermodynamic possibility of TiN precipitation in steel were also calculated. The results show that sulfide inclusions are evenly distributed and the content is low. The amount of oxide inclusions in CIESC: 4Cr5MoSiV1 steel is close to the ESR steel and lower than that in the EAF steel, and there are some differences along radial direction. Nitride inclusions are fine and the diameter of the largest one is 3-1 mum. With the increase of the centrifugal machine's rotational speed, the ratio of round inclusions increases and the ratio of sharp inclusions decreases. According to the experiment and the calculation results, it is pointed out that the largest diameter of non-metallic inclusions in the CIESC 4Cr5MoSiV1 casting is only 6.6 mum, and [N%][Ti%] in 4Cr5MoSiV1 steel should be controlled less than 4.4x 10(-5) in order to further reduce the amount and size of TiN inclusions.

Development of electroslag metallurgy and casting in China

The electroslag metallurgy has been developed since 1958. At present, all special steel plants have constructed electroslag metallurgical workshops. There are 86 Electroslag Remetting (ESR) furnaces in these steel plants with annual capacity of 100 000 tons. The products by ESR include 243 designations of steel and superalloy. The Chinese metallurgists have made significant achievements in the type and structure of electroslag remelting furnaces, eletroslag remelting technology, shaped castings by Electroslag Remelting Casting (ESRC), the manufacture of large-size ingots by ESR and the study of ESR mechanism. These achievements have already been recognized by foreign metallurgists.

Development and investigation of electroslag continuous casting

The principle and technological design of electroslag continuous casting （ESCC）, including bifilar mode, T-shaped mould, and metal level detecting system, are detailed. Remelting was carded out for 1Crl8Ni9Ti stainless steel with ESCC. The surface finish, chemical composition, macroand microstructures, and inclusions of the remelted billets were characterized. ESCC reduces the cost and increases the productivity in comparison to traditional ESR, while achieves comparably excellent products.

3-D Finite-Element Numerical Simulation of Centrifugal Induction Electrosalg Casting Solidification Process

A 3-D finite-element numerical simulation model of temperature field for CIESC casting solidification process was developed with the aid of ANSYS software and a series of corresponding experiments were made. The results showed that the good agreement was obtained between the numerical simulation and the experiments. Based on the numerical simulation results, the characteristics of temperature distribution in the castings during CIESC solidification process were analyzed and summarized. According to the G/R-1/2 method and numerical simulation results, there is no any shrinkage defect in the CIESC casting and structure or casting is fine and compact.

Correlation between current and cross-sectional area of parallel fixed-movable dual electrodes in ESC

Electroslag casting with parallel fixed-movable dual electrodes is a new method for achieving better quality of castings in complex mold cavities.In this work,a mathematical model,y=kx^2+(k+1)x,was established to describe the ideal correlation between the current ratio(y)and the cross-sectional area ratio(x)of the dual electrodes,where k is the filling ratio.Investigation was conducted on the electroslag casting process with dual electrodes of various cross-sectional areas,but at a constant k value.The experimental results indicated that the ideal correlation was obtained at the stable casting stage,and the fitting results were consistent with the experimental results at certain k values.The experimental findings show that better castings can be obtained when the current ratio is greater than 1.536 and the cross-sectional area ratio is greater than 0.5.