Titanium plate production process

Titanium plate production process

The production process of hot rolling and cold rolling is adopted for the titanium plate and strip.

Heating and hot rolling The slab is heated and rolled on a hot rolling mill to produce hot-rolled medium and thick plate products or cold-rolled billets. Because titanium metal is easy to absorb hydrogen and oxidize in the hot state, and it aggravates with the increase of temperature and time, therefore, the heating temperature of titanium and its alloy slabs is generally controlled between 850 and 1150 ℃, and the heating time depends on It depends on the heating method and the size of the blank. When the flame furnace is used for heating, the atmosphere in the furnace must be strictly controlled as a micro-oxidizing atmosphere. Titanium has good plasticity in hot state and low deformation resistance, but cold working is more difficult. Therefore, it is necessary to increase the total processing rate of hot rolling as much as possible to reduce the amount of cold processing. When the belt method is used for production, a thick slab is first rolled into a thick slab on a billeting machine, and then rolled to a thickness of 2 to 3 mm on a hot continuous rolling mill or a rolling mill with an in-furnace coiler. Coil, there is also a hot rolling mill from the billet to the thickness of 6-8mm, and then coiled or welded into a coil at its tail. When the block method is used for production, it is generally rolled on a single-stand hot rolling mill, and sometimes two or three heating, hot rolling, surface treatment, reheating, and hot rolling cycles are required to roll to the required thickness.

Surface treatment In order to remove the oxide gettering layer formed on the surface of the titanium plate (strip) billet during heating, hot rolling and annealing, surface treatment is required. The main treatment processes are acid washing after alkaline washing or acid washing after sandblasting (pill). The alkaline washing and pickling method is to first immerse the product in a molten alkali solution (NaOH) tank containing an oxidant (NaNO3). After the alkali wash, it is immediately water quenched, and then pickled in a nitric acid solution containing fluoride ion. Wash and dry again. The sandblasting (pill) pickling method uses compressed air to impact sand (iron pellets) on the working surface at high speed to remove the oxide layer, and then pickling and drying. During alkaline washing, the treatment of waste lye and alkali-containing waste gas is more complicated, and the production cost is relatively high. Sandblasting (pill) pickling is often used in the design.

Cold rolling Pure titanium is usually rolled at room temperature or slightly higher than room temperature. Some titanium alloys need to be heated to 100-200°C before rolling. The cold work hardening speed of titanium and titanium alloys is relatively fast. The total processing rate between two annealings is not more than 50% for pure titanium, and not more than 30%-40% for titanium alloys. It requires multiple intermediate annealing and multiple cold rolling to produce Produce thin products.
Annealing includes intermediate annealing and finish annealing. Intermediate annealing is carried out in a non-vacuum annealing furnace. After annealing, pickling is required to remove the surface oxide layer. Finishing annealing is generally carried out in a vacuum furnace. After annealing, the surface is smooth and no pickling is required. The cold-rolled slabs and strips should be degreased before annealing to remove surface oil stains to improve the surface quality of the strips after annealing.
Finishing and inspection According to the delivery conditions of various products, the finishing process includes rolling, straightening and finished product shearing. The inspection items include sampling inspection, appearance quality and dimensional tolerance inspection.

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