Continuous casting is an efficient, energy-saving and environmentally friendly raw material, which can be used to produce long products instead of ingot or blooming. The products produced include large, medium and small H-beams, rails, and small wire rods, which have the advantages of good quality and energy saving. In China, the new small wire rod production lines for H-beam, rail and ordinary steel all use continuous casting as raw material.
At present, the raw materials used for long products in China include steel ingot, continuous casting and forging billet. In 2010, China’s crude steel output was 626.65 million tons. Among them, the continuous casting ratio is 97.9%, the mold casting ratio is only 1.9%, and the other 0.2% are castings. That is to say, most of steel rolling (including long rod rolling) is based on continuous casting, and the total amount of steel ingot and forging billet is less than 2%. Among them, the number of forging blanks is less, and only a few products with high quality requirements, such as high-speed steel, cold work die steel, valve steel and products for military purposes, can use forging blanks.
China is short of scrap steel resources and power supply. Therefore, the development of short process in China is restricted, and the steel output produced by long process accounts for about 90% of the total output. With the gradual increase of its scrap resource accumulation, it may change in the future. However, at this stage, China’s steel production is still dominated by long process.
After half a century of development, converter steelmaking and continuous casting technology has undergone a series of process adjustment and optimization. The smelting process has now become: hot metal pretreatment – converter steelmaking – external refining – continuous casting. This process is very efficient and energy-saving. In the past, almost all kinds of steel that can be smelted by electric furnace can be produced by converter.
This process can produce the following steel grades:
steel grades
(1) Carbon structural steel Q195~0275, 08F, 010F, 08~50, etc.
(2) There are 47 varieties of alloy structural steel, including 20Mn~45Mn, 35, 42SiMn, 15Cr 45Cr, 12CrMo~42CrMo15CrMn~35CrM12CrNi~42CrNi.
(3) Spring steel 65~85, 65Mn, 55Si2Mn~60Si2Mn, 50CrV, etc.
(4) Bearing steel GC6~GCr15, GCr9SiMn~GCr15SiMn, etc.
(5) There are 93 series of stainless steel products including Cr series, Cr-Mn series, Cr-Ni series, Gr-Ni-Ti series, Cr-Ni-Mo series, Cr-Ni-Mo-Ti series, Cr-Ni-Mo-Cu series and Cr-Ni-Al series.
According to statistics, there are more than 180 steel grades in the world, which are made by converter primary smelting, refining furnace refining and continuous casting machine.
Continuous casting is good, but it is not omnipotent. In addition to the above series of steel grades, some steel grades still need to use die-casting ingots. There are mainly two kinds of steel: one is the steel that cannot be continuously cast, such as alloy tool steel 5CrMnMo, 5CrNiMoV, high-speed steel W18Cr4V, and high-temperature alloy N80AGH4169, GH2132; The other is that it can be produced by continuous casting technically, but the order quantity is too small, so it is not economical to produce by continuous casting method, and it has to be produced by mold casting.
