The tested bearing steel 9Cr18Mo (/% ： 0.98C, 0.21 Si, 0.32Mn, 0.005P, ＜0. 001S, 16.95Cr, 0.51Mo) is melted by 500 kg vacuum induction melting furnace (VIM) -electroslag remelting unit (ESR) -vacuum arc remelting unit (VAR) triplex process, forged breakdown and rolled to Φ30 mm bar products. The gas content, deleterious elements content and non-metallic inclusions in steel 9Crl8Mo are examined and analyzed. Results show that the triplex process is available to increase the cleanliness of bearing steel, the oxygen content in tested steel 9Cr18Mo is 0.0008% , nitrogen content is 0.0038% and the S content is ＜0. 001 % , and with controlling the Ti content and pentad-deleterious elements content in raw materials, in finished products the Ti content is ＜0.002% , the Sn, As and Sb content are respectively ＜0.002% and the Pb and Bi content are respectively ＜0.0001 % ； by triplex process the nonmetallic inclusions in steel is a little, and the inclusions with size less than 3μm amount are more than 90% of total inclusions up to quite high cleanliness level.Material Index Bearing Steel 9Cr18Mo, Cleanliness, VIM-KSR-VAR Triplex Melting Process, Inclusions.

The tested steel 0. 05C-14Mn-19Cr-0. 7N is melted by 1 t non vacuum induction furnace and remelted to ESR ingot. By sampling at center of ESR ingot and using Gleeble 3800 thermo-simulation testing machine the thenno tensile examination of tested steel at 800 ~ 1250 °C with strain rate 0. 005 ~ 10 s^-1 has been carried out to get the effect of temper ature and strain rate on reduction of area of tested steel, and the structure of steel tensile-tested at each temperature is ob served. Examination results show that with temperature increasing from 800 ℃ to 1 250 ℃ the tensile strength of tested steel decreases from 327 MPa to 68 MPa and the reduction of area of steel increases from 22% to 55% ；at 1200℃, with strain rate increasing from 0. 01 s^-1 to 10 s-1 the tensile strength of tested steel increases from 43 MPa to 109 MPa and the reduction of area of steel increases from 38% to 71%. Integrating the experimental results it is obtained that the optimized deformation parameters for high nitrogen austenite stainless steel 0. 05C-14Mn-19Cr-0.7N are rolling at 1200 ~ 1250°C with stain rate 1 ~ 10s^-1.

Effect of the non-electromagnetic stirring ( non-EMS) and the EMS with 6 Hz and 50 ~ 200 A in 1 t electroslag remelting (ESR) process on solidification structure o£ alloy GH4169 (/% : 0.04C, 0.21 Si, 0.05Mn, 52. 85Ni, 19. 80Cr, 5.20Nb, 3.05Mo, 0.55Al, 1.02Ti) has been studied. Results show that the EMS may obviously fine grains of alloy, increase ratio of equiaxed crystal and decrease spacing between secondary dentritic arms ； but as stirring electric current intensity is >100 A, the eutectic structure in ESR ingot increases to reduce the plasticity of ingot; as the current intensity is 50 A with frequency 6 Hz, the ratio of equiaxed crystal is max and the spacing between secondary dentritic arms is minimum, the Laves phase content in center of ESR ingot is lowest and the alloy with minor eutectic structure to get excellent plasticity of alloy.

The effect factors on intensity of cooling of large-scale ESR furnace mold have been analyzed by using heat transfer theory, it is obtained by calculation that the optimum water flow rate for the 1 800 mm diameter mold is 1. 2 m/s, and the optimum design scheme for high speed water case type mold with case layer thickness 10 mm is put forward. The production results by remelting 60 t 0.030C-17.10Cr-ll.80Ni-2.55Mo-0.072N austenite stainless steel ESR ingot with voltage 77. 5 V, current 19 kA, remelting speed 31. 6 kg/min and water rate 1. 2 m/s show that the formability of ESR ingot is better, and the forming quality of ESR ingot is improved with smooth ingot surface and uniform distribution of slag skim.

The effect of consumable electrode on ESR ingot cleanliness was investigated during electroslag remelting (ESR) of G20CrNi2Mo bearing steel. The results show that the ingot cleanliness is much correlated with that of electrode. The ingot oxygen content presents a rising trend with increasing electrode oxygen content. The SEM-EDS analysis reveals that the number density of low-melting-point CaO-MgO-Al ₂O ₃ inclusions in high oxygen-containing electrode is much larger than that in low oxygen-containing electrode. The low interfacial energy between low-melting-point inclusions and steel significantly limits the efficiency of inclusions removal, thus resulting in relatively high ingot oxygen content. With increasing carbon content before EAF tapping, the number of ingots less than 0.002 0% oxygen occupies total more than 90%.

In order to control structure non-uniformity and carbide segregation of high speed steel ingot, ingots of small size are usually produced by ESR, but its production efficiency is low, the rate of finished product is low. Long electrosiag billets with small specifications for ESR fest Withdrawing can improve production efficiency and finished product rate, we made 160 mm x 160 mm square billet of M2 high speed steel using T-type conductive crystallizer for ESR fast Withdrawing with different melting speed and forged and rolled, through the detection and analysis of the composition, low magnification, cast structure and carbide irregularity of the electroslag billet and the size of large particles of carbide, mean¬while ,it is compared and analyzed with Φ 220 mm ingot rolling for conventional ESR, analysis shows that electroslag billet for ESR fast Withdrawing with 400 kg/h remelting speed has stable composition and good macrostructure, the carbide variability and carbide dimensions of large particles of rolled materials produced are similar to those Φ 220 ingot rolling materials for conventional ESR, and the production efficiency and the rate of finished products have been improved obviously.

It was studied the quality of carbide, non-metallic inclusions and composition change of sulfur bearing M35 high speed steel (0. 015% ~ 0.030 S) using acid slag remelting in atmospheric conditions using the 1 t double electrode furnace. When the acid slag was remelting,the sulfur,silicon,manganese,chromium have a large difference between the two ends of the ingot, the difference reduced using the method of adding calcium sulfide when slag melting and adding manganese iron when Slag dump. The quality level of carbide nonuniformity granularity of sulfur bearing M35 high speed steel mill bar is similar to that of conventional alkaline slag,non-metallic inclusions class A is less than 1.5 ,B, C and D, which are less than or equal to 1.0.

Grade (/% ：0.3C-1.6Si-0. 8Mn-1.1Cr-0.48Mo-0.1 V)of ultra high strength steel has been melted by 6 t vacuum induction & vacuum arc remelting processes. Through comparing the structures and mechanical properties of this steel melt with different superheat degree,the test results show that the rating of banding structure decreases from 2.5 to 1 and the fracture toughness average value increases from 85 MPa . m ^1/2 to 116. 3 MPa . m ^1/2 when VIM casting temperature decreases from (1 600 ± 10) °C to (1 560 ± 10) °C . So the low temperature casting process is the key to improve the uniform of material.

Based on electromagnetic stirring (EMS) in the electroslag process fbr bearing steel GCrl5,the effects of EMS on the superalloy solidification structure and chemical composition are analyzed. The result is as follows: Electromagnetic electroslag can signiHcantly improve the heat transfer condition of ingot solidification process, reduce the formation of network carbide in steel GCrl5 ingot. At the same time, because of the effect of electromagnetic stirring, the segregation index of main elements such as C and Cr in the ingot is stable less than 1.03. When the stirring current is 50 A to 2(X) A, the frequency is 6Hz. , there is no net carbide in the center of the ingot, and the carbon segregation index is 1.02.

The ingredient and phases of solid phase slag without remelting liquid slag air cooling and with liquid-slag reaction remelting slag, air cooling of slag 70% CaF ₂-25% Al ₂O ₃-5% CaO for ESR of electrothermal alloy steel 0Cr21A16NbRE with normal remelting process (A =2800 A,V =30 V) are studied,and the burning loss of RE elements in liquid is analyzed. The results show that without remelting air cooling slag has not RE elements it locates in CaF ₂ -CaO • 2Al ₂O ₃-CaO • 6A1 ₂O ₃ sub-triangle. The solid phase slag with liquid-slag reaction can be divided into five layers with different colors, difierent phase, the content of CaF ₂ on the top is highest and decreases layer by layer, A1 ₂O ₃ increase simultaneously ,RE oxide is found in layers and at the middle and bottom its content is higher, (Ce,La)x( A10 ₂ )  y is major RE oxide phase in slag, which density is high. It is obtained by calculation that slag oxidability is stronger in the middle and bot¬tom of slag,RE element in steel is oxided here. Increasing the Y ₂O ₃ amount in slag is favourable to increase the RE element Y content in ESR ingot.

By analyzing microstructure and inclusions, analyzing chemical composition and mechanical properties of 4J36 alloy (/% ：0. 17 ~0.18C,0. 18 〜0.27Si,0.39 〜0. 40Mn,0.009P, < 0.0005S,35. 8 〜36.ONi) before and after ESR(electro-slag remelting) , the effect of ESR on microstructure and mechanical properties of 4J36 alloy is studied. The results show that after ESR the chemical composition of 4J36 has almost no change, the sizes of gains decrease, and the amount and sizes of inclusions also decrease. Yield strength and tensile strength are improved to a certain extent, elongation increases from original 34% to 58% , and impact energy at - 196℃. increases from original 145 J to 208 J.

The composite roll is a kind of bimetallic composite material which consists of a high wear-resistance mate¬rial as the working layer and a high strength, toughness material as the core respectively. In this paper, a systematical introduction is given for the preparation of bimetallic composite roll by electroslag metallurgy technology including ESR clad¬ding method, electroslag surfacing by liquid metal and consumable mold cladding method at home and abroad. The influence of consumable electrode form, conductive circuit scheme, supply method of the outer metal and equipment structure on the bimetallic cladding process and the comprehensive performance of composite roll are analyzed. At the same time, the basic process characteristics and control keys technology of the different methods are summarised. Based on the analyses of the development history of electroslag cladding technology and the stability control of composite roll performance, the future prospect and development of the preparation of bimetallic composite roll by electroslag cladding method is prospected.

The oxygen and nitrogen content of GH3128 alloy with two smelting processes of "VIM + ESR" and "NVIM + ESR" are measured by oxygen nitrogen analyzer, and the thermodynamic calculation of deoxidation and denitrifiation has been carried out. The composition, size distribution and quantity of inclusions in GH3128 alloy with two smelting processes are analyzed by ASPEX SEM . The results show that： The process of M VIM + ESR" can remove the N in the alloy more effectively, the inclusions are mainly Al-Ti-0 composite oxide inclusions, with a small number of Al ₂O ₃ and TiO _x oxide inclusions, the inclusions in alloy by process of "NVIM + ESR" are not only oxide inclusions, but also sulfide and nitride inclusions. And uses the vacuum smelting process can effectively reduce the number of inclusions, and refine the inclusion.

Valve steel NCF3015 Φ280 mm x 1700 mm electrode (/% ： 0. 03 ~0. 08C, 13.5 〜15. 5Cr, 30 ~ 33.5Ni, 1.7-2. 1A1, 2.4 ~2.9Ti, 0.65 ~0. 80Mo, 0.65 ~0.80Nb, 0.002 - 0.006B) is remelted into Φ340 mm 0. 80 t electroslag ingot with full coaxial inert gas shielding. Under the conditions of full argon protection with ternary premelted slag 70CaF ₂-15Al ₂O ₃-15CaO and a melting rate 4 kg/min, the amount of burning loss of Al and Ti and the change of Si and S removal rate in the process of gas valve steel NCF3015 electroslag remelting are tested, and the mechanism is explained. The results show that Al is the main burning element relative to Ti, the average burning loss of Al is -0. 071% , and the average burning loss of Ti is -0.035% ; and the burning loss of Al and Ti gradually decreases from the bottom to the top of electroslag remelted ingot. Compared with the burning loss rate of conventional electroslag remelting ,argon protection has a significant effect on reducing the burning loss of Al and Ti, The burning loss of Al and Ti causes a slight increase in Si content at the initial stage of remelting. The slag system has a certain desulfurization effect, with an average desulfurization rate of 36.7 % .

Nb and Si diffusing rule at 1 190℃ in GH2907 (0.02C,38,20Ni,13.92Co,4. 92Nb,l. 60Ti,0.32Si) alloy ϕ508 mm 3 t ingot is studied by using optical microscope, scanning electron microscope etc. Studies have shown that the dendrite spacing of the GH2907 alloy ϕ508 mm ingot is approximately 110μm, the apparent diffusion coefficients of Nb and Si at 1190℃ are respectively D = (0.704 ±0.041) X 10 ^-14m ²/s and D = (1. 870 ±0.511) x 10 ^-14m ²/s. Theoretical calculation shows that,when Nb diffuses 44.8 ~50.3 h or Si diffuses 14.0~24.5 h at 1 190℃,the residual segregation index δ _i will reach 0.02 respectively.

he morphology of carbides and the thermoplasticity of high speed steel can be improved by inoculating with   rare   earth.   Test   and   batch   production   results   show   that   by   20t   MIF+25tLF+25tVD+4tESR   process,as   Al 0. 12%  in  steel  in  VD  process  adding  0. 1%  lanthannm-cerium  mixed  RE  alloy  and  using  6%  REO ₂  slag  series  in  ESR process,the  RE  content  in  M42  steel  is  0.027%～0.038%  stably  to  obviously  improve  inclusions  morphology  and  hot plastisity  of steel.

By vacuum induction melting 08Cr9CoMo steel using MgO crucible, the pure iron is derusted and baked with other alloys, the charging ingredients are 0. 06% C, 1. 3% Co, 9. 0% Cr, 1. 5% Mo, 0. 02% La-Ce, the balance is iron,turn on the power with vacuum ≤10 Pa, controlling the vacuum 25 ~30 Pa during the melting period, controlling the liquid temperature 1 600 °C and the vacuum 10 Pa during the refining period, and refining for 20 min, adding 0. 02% La-Ce before casting, the final analysis result is 0. 022% C and 0.002 8% 0. The carbon deoxidation capacity under vacuum is calculated by thermodynamics, and it is significantly enhanced as vacuum reduces, the relationship between oxygen supply of the MgO crucible and vacuum is analyzed by thermodynamic calculation, when the vacuum is lower than 25 Pa, the crucible decomposes and supplies oxygen more significantly, when the decomposition rate of the MgO crucible is equal to the carbon deoxidation rate, the molten steel reaches the minimum oxygen content.

The 12Cr2Mol VR steel plate production flow is 100 t EAF-LF-VOD-CC-ESR-rolling process. In the electroslag remelting process, the processes such as melting rate reduced by (160 ~ 180) kg/h and nitrogen protection are adopted ； low speed and large reduction rolling process is adopted in the rolling process ； after rolling, 650 ~ 700 °C longtime holding hydrogen diffusion annealing process is adopted. Normalizing at 930 ~ 950 °C ( accelerated cooling) + tempering process at 680 -700 °C are adopted during heat treatment. The surface quality of the produced steel plate is good. The flaw detection level meets the requirements of NB/T 47013. 3-2015 with No. 1 amendment T I rating. The composition and microstructure of the steel plate are uniform. The mechanical properties are stable to meets the technical requirements.

The GH2132 alloy (1.90% ~2. 30%Ti) has the problems of large loss of Ti element ( A[Ti]0. 37% ~ 0. 57% ) in ESR process, the Ti content in steel is only 1. 83% ~ 1. 89% in ESR middle and last period. By adopting (/% ) CaF： Al ₂O ₃： CaO： TiO ₂ =75： 15： 5： 5 slag system to replace original CaF270% + Al ₂O ₂0% slag system, the unstable oxide (SiO ₂ + FeO) in the slag is controlled to be less then 0. 6% , and die controlled melting rate of the smelting process decreases from 6. 1 -6. 3 kg/min to 5. 3 -5. 6 kg/min, etc technological measures, as a result, the Ti content in steel at ESR ingot each part is 2. 06% ~2. 21% , and the Ti burning loss A[Ti] decreases to 0. 19% ~0. 34%, ESR ingots are sampled to check the inclusions after forging, and it is found that the inclusions have also been significantly improved after the process adjustment. The class inclusions of D fine system is controlled below rating 0. 5, which meets the requirements.

By using combination teachnology of 20 t EAF-LF-VD, 20 t argon protection ESR unit remelting, 1 250 ~1 280 ℃ high temperature homogenization treatment, 60 MN oil pressure quick forging machine multiple forging and 1 000 〜1 050 ℃ high temperature solution treatment process, the inclusion(≤0.5 rating) , structure and lateral impact energy (KV2 25 〜31 J) of produced 640 mm x 1 100 mm 4Cr5Mo2V heavy die steel are higher than the requirement in standard NADCA#207-2018 for advanced steel leave,and the isotropy of steel reaches 0.95.