The extremely thick pure industry titanium plate refers to a titanium plate with a thickness> 120mm, which is a special titanium plate used in the production of serious technical equipment such as boilers and pressure vessels, high-rise buildings, heavy machinery, and mold making. Because the functional requirements of large single-weight and extremely thick titanium plates are strict and special, it is necessary to ensure high-quality extremely thick blanks with high compression ratios. This is the first demand regardless of the production method and which blanks are used. During the exercise, the strengthening method is adopted. After pre-treatment, desulfurization and dephosphorization are performed, and the titanium bag is degassed to obtain pure titanium water. The details are as follows:
1. Titanium water should be desulfurized to less than 0.002% and dephosphorized to less than 0.005%. In addition, in order to avoid temper brittleness, it is also necessary to reduce impurity elements such as Sn, As, Sb.
2. C is the most obvious element affecting low-temperature impact. For thick standard E-grade titanium plates, the C content can be appropriately reduced; together controlling the intermediate segregation of the continuous casting slabs is conducive to improving the impact toughness.
3. The demand for titanium smelting adopts the low-hydrogen exercise method. After dehydrogenation of the titanium water tank, the hydrogen content should be reduced to 0.7 × 10-6, and the amount of hydrogen absorbed in the slab must be strictly controlled below 0.2 × 10-6.
4. In order to avoid the internal shortcomings of hydrogen, both slabs and titanium plates need dehydrogenation heat treatment process. In order to compact the internal looseness, the titanium ingot is cast and heavily pressed, and is equipped with a chamber heating furnace and a heat treatment furnace.
5. Because hydrogen and cracks will deteriorate the internal quality, it is necessary to adopt quintessential methods to improve the purity of titanium water, and use degassing methods such as titanium water RH, VD, DH, drip to completely remove hydrogen. Titanium refining hydrogen content is generally (3-5) × 10-6, after degassing treatment can reach (1-2) × 10-6.
6. In the production process of extra-thick titanium plates, if the hydrogen is not sufficiently dispersed in the slab, the internal defects (white spots) will easily occur after the accumulation of hydrogen in the middle of the plate thickness. In response to this, some titanium slabs have been selected to use heat preservation furnaces and slow cooling pits for dehydrogenation heat treatment. That is, after slow cooling, the slab needs to be loaded into the heat treatment furnace at a temperature above 200 ° C, and the temperature is kept at 650 ° C for a certain time, and the annealing time depends on the hydrogen content.
7. Titanium ingots and titanium species also have a great influence on segregation, and the head and tail volume should be severely controlled.