Superhigh strength thick steel plate capable of large-line energy welding and its manufacturing method

Abstract

This is a super intensive thick steel board which can be welded with jug line power. It contains 0.01-0.06%C, 0.10-0.50%Si, 1.00 -1.40%Mn, 0.010-0.050%Nb, 0.040-0.090%V, 0.60-1.00%Cu, 0.20-0.50%Cr, 0.20-0.50%Mo, 0.50-0.80%Ni, 5ppm-30ppmB, 0.005-0.020%Ti, 0.040-0.070%Als, and remained Fe and inevitable impurity: 0.065<=(%Cu*%V)<=0.085. The producing method includes: casting technique, slab heating, hot rolling, which is asynchronous rolling in austenite non-crystallized area, strain relaxation and direct cooling by quenching. This invention associates well the steel board's high intensity, high ductility and good weldability. It decreases the quantity of alloying agent and reduces the cost for steel board's production. It can as well improve the low-temperature flexibil ity and welability of the steel board, as it realizes welding with jug line power. As a result, it needs no pre-heating to weld steel board above 0 degree Centigrade.

Description

technical field [0001] The present invention relates to a kind of ultra-low carbon low-alloyed steel heavy plate containing Nb (ultra-low carbon low-alloyed steel heavy plate), which obtains 5 μ m ~ 10 μ m fine bainite / martensite lath grains, and the yield strength is greater than 800 MPa , Ultra-low carbon bainite / martensitic thick steel plate with excellent low temperature toughness and weldability. Background technique [0002] As we all know, low-carbon (high-strength) low-alloy steel is one of the most important engineering structural materials, widely used in oil and gas pipelines, offshore platforms, shipbuilding, bridges, pressure vessels, building structures, automobile industry, railway transportation and machinery manufacturing . The properties of low-carbon (high-strength) low-alloy steel depend on its chemical composition and the process system of the manufacturing process, among which strength, toughness and weldability are the most important properties of low...

AI Technical Summary

Problems solved by technology

In this way, the alloy content of the steel plate is high, and the carbon equivalent CEV and welding cold crack sensitivity index Pcm are also high, which brings great difficulties to on-site welding. Preheating is required before welding, heat treatment is required after welding, and welding costs increase. Reduced welding efficiency and worsened working environment at the welding site