A kind of low-carbon bainitic weathering steel and its production method

Abstract

The invention discloses low-carbon bainite weathering resistant steel and a production method thereof. The steel is prepared from the following chemical components by weight percent: C equals to 0.03-0.08, Si equals to 0.50-0.80, Mn equals to 1.00-1.80, P is less than or equal to 0.015, S is less than or equal to 0.005, Al equals to 0.02-0.05, Ti equals to 0.008-0.020, Nb is less than or equal to0.020, Cu equals to 0.50-0.80, Ni equals to 0.50-1.00, Ca is less than or equal to 0.006 and Ca / S is greater than or equal to 1.5, the balance of Fe and inevitable impurity elements; and Mo and Cr canbe selectively added, and Mo is less than or equal to 0.30%, and Cr is less than or equal to 0.30%. A microscopic structure of the steel is formed by 95% or above of carbon-free bainite, a little austenite on the crystal boundary and a Cu-Ni ageing precipitated phase, wherein the yield strength thereof is greater than or equal to 485 MPa, the tensile strength is greater than or equal to 585 MPa,the percentage elongation after fracture is greater than or equal to 25%, and the Charpy impact energy in -40 DEG C is greater than or equal to 120 J. The low-carbon bainite weathering resistant steelis clean in steel, uniform in texture, low in internal stress, and good in surface quality, and has the good weather resistance.

Description

technical field [0001] The invention belongs to the technical field of low-alloy steel production, and in particular relates to a low-carbon bainite weathering steel and a production method thereof. Background technique [0002] Weather-resistant steel, also known as atmospheric corrosion-resistant steel, often adds a small amount of alloying elements such as Cu, P, Cr, Ni, and Mo. Compared with ordinary carbon steel, weathering steel has better atmospheric corrosion resistance; and compared with stainless steel, weathering steel not only reduces the cost significantly, but also its mechanical properties and welding performance are easier to meet various engineering needs. Therefore, weathering steel is widely used in bridges, marine engineering, containers, railway carriages and other fields. [0003] The early research on weathering steel mainly focused on the improvement of the ability of the addition of alloying elements to resist atmospheric corrosion. For example, re...

AI Technical Summary

Problems solved by technology

There are also weathering steels used in the normalized or annealed state, but the microstructure is often composed of ferrite + pearlite, and there is a micro-galvanic interaction between cementite and ferrite in pearlite, along with the anode ferrite The dissolution of cementite in the cathode gradually accumulates on the surface of cementite, which gradually increases the cathode area, resulting in continuous accelerated corrosion of pearlite.

Images