30CrMnSiB steel, weldless steel tube for cylinder and method of manufacturing the same

Abstract

The invention provides a seamless steel pipe and a production method thereof used for 30CrMnSiB steel and cylinders. The 30CrMnSiB comprises the following components: 0.22 to 0.35 percent of carbon, 0.90 to 1.20 percent of silicon, 0.80 to 1.10 percent of manganese, 0.80 to 1.10 percent of chromium, 0.0005 to 0.0035 percent of boron, 0.05 percent or less than 0.05 percent of titanium, 0.035 percent or less than 0.035 percent of phosphorus, 0.035 percent or less than 0.035 percent of sulfur, 0.30 percent or less than 0.30 percent of nickel, 0.20 percent or less than 0.20 percent of copper, 0.10 percent or less than 0.10 percent of molybdenum, 0.05 percent or less than 0.05 percent of aluminum, balance iron. The initial smelting of the seamless steel pipe is performed through a converter oran electric furnace, the fine smelting is carried out through an LF furnace so as to produce a steel ingot used for a rolled pipe, or the steel ingot used for the rolled pipe is manufactured with a cyclical pipe rolling machine unit or a continuous pipe rolling machine unit through continuous casting, and after the quenching and high temperature tempering and seasoning heat treatment are implemented to the manufactured seamless steel pipe, the yield point Delta-s is within 945 to 1230MPa, the tensile strength Delta-b is within 1050 to 1370MPa, the rupture elongation rate Delta-5 is 12 to 16.5percent, the normal temperature impact power Aku2 is 34 to 91J, and after the seasoning heat treatment is implemented to a hot rolling final steel pipe, the hot rolling final steel pipe can be applied in various hydraulic cylinder bodies in the engineering machinery and coal mine hydraulic support fields.

Description

technical field [0001] The invention relates to a seamless steel pipe for a cylinder body and a production method thereof, belonging to the field of iron and steel metallurgy. Background technique [0002] In the 1970s, domestic seamless steel pipe manufacturers represented by Chengdu Seamless Steel Tube Factory developed 27SiMn, which can save more expensive alloying elements such as Cr and Mo, instead of 25CrMo4, 30CrMo, 40Cr, 30CrMnSi and other materials selected abroad. The steel type is used to make seamless steel pipes for parts such as cylinder blocks and cylinder bodies. Except for a few seamless steel pipes for domestic hydraulic cylinders, the main steel grade is 27SiMn steel. After more than 30 years of use, it has been shown that 27SiMn steel has high strength, high toughness, good wear resistance, good weldability, machinability and chrome plating performance after quenching and tempering, and can meet the requirements of general hydraulic prop pipes and other ...