High manganese steel with ultra-low yield ratio and manufacturing method thereof

Abstract

The invention discloses high manganese steel with an ultra-low yield ratio and a manufacturing method thereof. The high manganese steel comprises, by weight, 0.010-0.090% of C, 0.15-0.60% of Si, 10.0-16.0% of Mn, 0.020-0.040% of Nb, 0.005-0.03% of Ti, 1.0-4.0% of Ni, 0.020-0.060% of Al, no more than 0.020% of P, no more than 0.010% of S, no more than 0.0080% of N and the balance Fe and inevitableimpurities. Stacking for slow-cooling is conducted for more than 72 hours after continuous casting, and the temperature of a plate billet during cleaning is 100-200 DEG C; the heating temperature is 1150-1250 DEG C; at the first stage, the rolling starting temperature is 1150-1030 DEG C, and the finished rolling temperature is 1040-980 DEG C; at the second stage, the rolling starting temperature is 950-850 DEG C, the finished rolling temperature is 900-750 DEG C, and air cooling is conducted after rolling; and thermal treatment of one of normalizing, quenching, tempering or quenching + tempering is conducted after rolling. The yield ratio of the produced high manganese steel is 0.12-0.39, and the produced high manganese steel has excellent toughness and low-temperature toughness.

Description

technical field [0001] The invention belongs to the field of metal materials, in particular to a high manganese steel with extremely low yield ratio and a manufacturing method thereof. Background technique [0002] Traditional high-strength medium and heavy plate products generally adopt low carbon (0.06% ~ 0.2%) and low manganese (Mn: 1.0% ~ 1.8%), and add precious metal elements such as Cr and Mo at the same time. Production by cooling process or heat treatment process. And as the thickness of the steel plate increases, it is necessary to add a large amount of alloying elements such as Cr and Mo to improve hardenability, which greatly increases the production cost. At the same time, it is supplemented by an increase in the C content, which seriously deteriorates the weldability and low temperature toughness. Moreover, my country is a country with little Mo and no Cr resources, and the application of a large amount of precious metal elements such as Cr and Mo will highligh...

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Problems solved by technology

[0011] Although most of the high-manganese steels disclosed in the above documents have achieved high strength and high toughness, there are not many involving low yield ratio. The content of C and Mn in the alloy composition design is relatively high, and the process is mostly ingot casting. Cooling and annealing treatment, complex process and high cost

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