Seamless steel tube for 27SiMnB steel, cylinder and production method thereof

Abstract

The invention provides 27SiMnB steel, a seamless steel pipe used for cylinders and a production method thereof. The components of the 27SiMnB steel are as follows: 0.24 percent to 0.32 percent of carbon, , 1.10 percent to 1.40 percent of silicon, 1.10 percent to 1.40 percent of manganese, 0.0005 percent to 0.0035 percent of boron, equal to or less than 0.05 percent of titanium, equal to or less than 0.035 percent of phosphorus, equal to or less than 0.035 percent of sulfur, equal to or less than 0.30 percent of chromium, equal to or less than 0.30 percent of nickel, equal to or less than 0.20percent of copper, equal to or less than 0.10 percent of molybdenum, equal to or less than 0.05 percent of aluminum, and the rest is iron. The invention adopts converter or electrical furnace primarymelting, LF furnace refining, rolling pipe steel ingot or continuous ingot casting, cycle rolling pipe units or continuous rolling pipe units to roll; the yield stress sigma s of the produced seamless steel pipe after quenching and high-temperature tempering and hardening heat treatment is 950MPa to 1050MPa, the tensile strength sigma b is 1040MPa to 1180 MPa, the extensibility after breakage delta 5 is 15 percent to 18 percent and the impact power under normal temperature Aku2 is 85J to 120J; the hot rolled finished steel pipe after hardening heat treatment can be applied to all hydraulic cylinders in fields, such as engineering machinery, coal mine hydraulic supports, etc.

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 ...