Seamless casing pipe process

Seamless casing pipe process: physical and chemical test tube into the factory cut length → pickling → Check → heating → grinding → pickling → Check perforation cleanup → annealing → phosphide saponification → drawing → straightening → NDT Automation Painted → bundling package → storage.

Ingredients request
Because of the non-metallic inclusions OCTG, gas content and other requirements more stringent, while the chemical composition requirements, the lower S, P content requirements; thus requiring the original wood materials into the furnace and pouring system dry, clean, good baked into the furnace steel material requirements including S, low P content. According to the above requirements, develop ingredients structure: 45% ~ 60% iron + iron, 40% to 55% of high quality scrap (low phosphorus), slag (lime) 150 kg / furnace.

EAF process control
Electric control is the focus of the pre-oxidation do to P operations. Made good foaming slag, oxidation endpoint carbon> 0.10%, carried out during the pre-deoxy-manganese alloy steel used in the steel-third of the time to add a little stream with steel Al blocks. Should use low-phosphorus alloys, manganese alloys alloying operations.

Refining Process Control
Because electric furnace process control better, refining furnace slag in place good fluidity, deep-deoxy change slag refining process faster, adjusted by the content of the slag condition, slag basicity average of 3.5, Σ (FeO) ≤0.5%, white residue retention time in 30 min or more, deoxy-sufficient, smelting ideal composition control. Contents of the other residual elements Zn, Pb, Sb, Cu, As, Sn, Bi, etc. are ≤0.006%. LF out of the top steel feeding Ca-Si-wire operation, carried out after VD vacuum treatment of steel, the vacuum (<67 Pa) hold time> 15 min, piercing. After the soft argon no less than 10 min, further removal of the steel gas inclusions.

Casting Process Control
Casting process using full protection, low superheat pouring tundish high level and the constant pull speed operation, reduced inclusions in steel content. Tundish superheat were controlled within 25 ℃, the casting speed steady at 0.65m / min; using high quality powder and mold electromagnetic stirring technology, help to improve the physical quality of the slab to prevent all kinds of surface defects and low magnification produce. If the casting machine two cold water properly controlled, can cause thermal stress in the uneven distribution of high-temperature range, or straightening temperature is brittle temperature range, leaving the slab surface cracks. casing pipe brittle temperature range appear in the third 750 ~ 920 ℃. For this purpose two weak cold cold adopted to ensure the straightening temperature> 920 ℃, to prevent stress cracks.

Rolling process control
To make the performance of hot-rolled steel tube wells meet API specifications of steel, hot-rolled steel tube must be prepared tissue. Therefore, the provisions of the slab is heated evenly, open rolling temperature control in 1150 ~ 1220 ℃, rolling rhythm control is good, the finish rolling temperature at 920 ~ 950 ℃.