A high-strength steel plate with a thickness of 8-25mm and a low yield ratio tank car and its manufacturing method

Abstract

The invention relates to an 8-25mm thickness type low-yield-ratio and high-strength steel sheet for a tank truck. The 8-25mm thickness type low-yield-ratio and high-strength steel sheet for the tank truck solves the shortages such as high yield ratio, low welding performance and high production cost of a current steel sheet. The 8-25mm thickness type low-yield-ratio and high-strength steel sheet for the tank truck is characterized in that a C+Mn+Cr and Nb and Ni microalloying system is adopted; the steel comprises the following chemical components in percentage by weight: 0.08-0.15% of C, 0.05-0.20% of Si, 1.50-2.00% of Mn, not greater than 0.012% of P, not greater than 0.005% of S, 0.32-0.45% of Cr, 0.10-0.20% of Ni, 0.02-0.07% of Nb, and the balance Fe and inevitable impurity elements; and the formula (seeing the description) is met. A normalizing technology is carried out for production; the mechanical performance meets the condition that the yield strength is not less than 400MPa;the tensile strength Rm is not less than 600MPa; the ductility A50 is not less than 32%; the yield ratio is not greater than 0.75; the transverse impact energy KV2 at below 50 DEG C is not less than 47J; the technical processes include preparing molten iron through a blast furnace, performing KR treatment on the molten iron, performing smelting in a 120-160t oxygen converter, performing refining in an LF (ladle furnace), performing treatment (refining) in an RH vacuum furnace, performing continuous casting, heating a casting blank, performing controlled rolling, performing normalizing, detecting cracks, and inspecting. The 8-25mm thickness type low-yield-ratio and high-strength steel sheet for the tank truck has the characteristics of being low in yield ratio, high in strength, outstandingin low-temperature toughness and plasticity, and high in welding performance; and in addition, the production cost is low; and the operability is high.

Description

technical field [0001] The invention relates to a high-strength steel for tank cars with a thickness of 8-25 mm and a low yield ratio and a manufacturing method thereof. It belongs to the technical field of low alloy steel. Background technique [0002] After decades of rapid economic development, my country's oil consumption is increasing day by day, and environmental pollution and other issues are becoming increasingly prominent. With the awakening of national awareness of environmental protection, my country's energy-saving emission reduction and environmental protection policies are gradually promoted and implemented. The market's requirements for mobile tankers are becoming more and more stringent. Those mobile tankers with small volume-to-weight ratio and low carrying efficiency are gradually eliminated. has become a trend. Since my country began to use 600MPa high-strength steel at the beginning of the 21st century, the volume of mobile tankers has become larger and ...

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