JIANG Zhouhua
,
DONG Yanwu
,
LIANG Lianke
,
LI Zhengbang
钢铁研究学报(英文版)
The pickup of hydrogen during electroslag remelting process for several slags consisting of CaF2Al2O3CaOSiO2MgO had been investigated. The laboratoryscale remelting experiments had been carried out in open air and waterfree argon atmosphere, and then the influencing factors were analyzed. It had been found that the hydrogen content in steel varied with different slag compositions. The compositions and state of slag had significant effect on the hydrogen level in steel. Partial return slag and premelted slag could avoid the hydrogen pickup especially in the early stages of the process. However, premelted slag was the optimum state to control the hydrogen pickup in steel. Experimental results indicated that waterfree argon atmosphere was very favorable to the control of hydrogen in steel in the normal remelting period.
关键词:
electroslag remelting; hydrogen; calcium fluoride; premelted slag; protective atmosphere
LI Huabing
,
JIANG Zhouhua
,
ZHANG Zurui
,
YANG Yan
钢铁研究学报(英文版)
The fine grained structures of nickelfree high nitrogen austenitic stainless steels had been obtained by means of cold rolling and subsequent annealing. The relationship between microstructure and mechanical properties and gain size of nickelfree high nitrogen austenitic stainless steels was examined. High strength and good ductility of the steel were found. In the grain size range, the HallPetch dependency for yield stress, tensile strength, and hardness was valid for grain size ranges for the nickelfree high nitrogen austenitic stainless steel. In the present study, the ductility of cold rolled nickelfree high nitrogen austenitic stainless steel decreased with annealing time when the grain size was refined. The fracture surfaces of the tensile specimens in the grain size range were covered with dimples as usually seen in a ductile fracture mode.
关键词:
grain refinement strengthening;nitrogen;nickelfree high nitrogen austenitic stainless steel;HallPetch equation
LI Huabing
,
JIANG Zhouhua
,
SHEN Minghui
,
YOU Xiangmi
钢铁研究学报(英文版)
A simple and feasible method for the production of high nitrogen austenitic stainless steels involves nitrogen gas alloying and adding nitrided ferroalloys under normal atmospheric conditions. Alloying by nitrogen gas bubbling in FeCrMnMo series alloys was carried out in MoSi2 resistance furnace and air induction furnace under normal atmospheric conditions. The results showed that nitrogen alloying could be accelerated by increasing nitrogen gas flow rate, prolonging residence time of bubbles, increasing gas/molten steel interfaces, and decreasing the sulphur and oxygen contents in molten steel. Nitrogen content of 069% in 18Cr18Mn was obtained using air induction furnace by bubbling of nitrogen gas from porous plug. In addition, the nickelfree, high nitrogen austenitic stainless steels with sound and compact macrostructure had been produced in the laboratory using vacuum induction furnace and electroslag remelting furnace under nitrogen atmosphere by the addition of nitrided alloy with the maximum nitrogen content of 081%. Pores were observed in the ingots obtained by melting and casting in vacuum induction furnace with the addition of nitrided ferroalloys and under nitrogen atmosphere. After electroslag remelting of the cast ingots, they were all sound and were free of pores. The yield of nitrogen increased with the decrease of melting rate in the ESR process. Due to electroslag remelting under nitrogen atmosphere and the consequential addition of aluminum as deoxidizer to the slag, the loss of manganese decreased obviously. There existed mainly irregular Al2O3 inclusions and MnS inclusions in ESR ingots, and the size of most of the inclusions was less than 5 μm. After homogenization of the hot rolled plate at 1 150 ℃×1 h followed by water quenching, the microstructure consisted of homogeneous austenite.
关键词:
nitrogen gas alloying;nitrided ferroalloy;high nitrogen austenitic stainless steel;vacuum induction melting;electroslag remelting
DONG Yanwu
,
JIANG Zhouhua
,
LI Zhengbang
钢铁研究学报(英文版)
Experiment was carried out after the process parameters were calculated by the model previously established. The relationship between interdendritic spacing and local solidification time (LST) mainly determined by process parameters was exposed. Furthermore, the extent of segregation was studied. The results indicate that LST and interdendritic spacing are the largest and the amount of Laves phase as a result of the niobium segregation is the highest in the center of the ingot, whereas the opposite results are obtained at the edge of ingot. The extent of element segregation and the amount of Laves phase can be reduced when appropriate parameters are used. Therefore, the duration of subsequent homogenization treatments for 718 is shortened and the alloy quality is improved.
关键词:
electroslag remelting;Inconel 718;segregation;local solidification time;interdendritic spacing
ZHAN Dongping
,
ZHANG Huishu
,
JIANG Zhouhua
钢铁研究学报(英文版)
To confirm the effects of AlMnCa and AlMnFe alloys on the deoxidization and modification of Al2O3 inclusions, experiments of 4heat low carbon and low siliconaluminum killed steels deoxidized by AlMnCa and AlMnFe alloys were done in a MoSi2 furnace at 1 873 K. It is found that the 1# AlMnCa alloy has the best ability of deoxidization and modification of Al2O3 inclusions than 2# AlMnCa and AlMnFe alloys. Steel A deoxidized by 1# AlMnCa alloy has the lowest total oxygen content in the terminal steel, which is 37×10-6. Most of the inclusions in the steel deoxidized by 1# AlMnCa alloy are spherical CaOcontaining compound inclusions, and 891% of them are smaller than 10 μm. The diameter of the inclusion bigger than 50 μm is not found in the final steels deoxidized by AlMnCa alloys. Whereas, for the steels deoxidized by AlMnFe alloys, most inclusions in the terminal steel are Al2O3 or Al2O3MnO inclusions, and a few of them are spherical, and only 768% of them are smaller than 10 μm. Some inclusions bigger than 50 μm are found in the steel D deoxidized by AlMnFe alloy.
关键词:
steelmaking;deoxidization;inclusion;AlMnCa alloy;AlMnFe alloy
