Control method for ultra-low carbon steel CH1T edge fine grains

Abstract

The invention relates to a control method of ultra-low carbon steel CH1T edge fine grains. The control method of the ultra-low carbon steel CH1T edge fine grains comprises the following steps of controlling the heating temperature of a steel billet at 950 to 1120 DEG C to ensure that the steel billet is fully austenitized; and controlling the initial rolling temperature of the steel billet to be 1000 to 1060 DEG C, controlling the inlet temperature of a finishing mill to be 930 to 970 DEG C, controlling the inlet temperature of a reducing and sizing mill of a rolled piece to be 920 to 960 DEG C, and controlling the spinning temperature to be 840 to 860 DEG C. By adjusting the rolling process, rolling of a finishing mill group and a reducing and sizing mill group between two phase areas is effectively avoided, and the mixed crystal phenomenon of steel wire rods is avoided from the source, so that an ultra-low carbon steel CH1T edge fine grain structure can be stably controlled, the edge grain size reaches the 10.5 to 11.5 level, a core structure reaches the 7.5 to 8.5 level, the fine grain layer thickness reaches 700 to 1000 micrometers, the surface hardness after steel wire drawing is ensured, and customer personalization requirements are met.

Description

technical field [0001] The invention relates to the technical field of producing ultra-low carbon steel CH1T, more specifically, it relates to a method for controlling the edge fine grain of ultra-low carbon steel CH1T. Background technique [0002] Ultra-low carbon steel CH1T wire rod is mainly used to manufacture hollow rivets for construction machinery, toys, and hollow rivets for luggage. This product has very high requirements on the internal quality and surface quality of the wire rod. The core requirement of this steel type is to process rivets with drawn steel wire. There is no cracking problem during the molding process. When the customer has no technical requirements for the surface hardness of the ultra-low carbon steel drawing wire, the heating temperature is 950-1120°C, the starting rolling temperature is 970-1030°C, the pre-finishing entrance temperature is 910-970°C, and the sizing machine entrance temperature is 910~950℃, spinning temperature 900~920℃, the S...

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Problems solved by technology

[0004] 1. The heat treatment temperature Ac3=1023°C and Ar3=914°C of ultra-low carbon steel CH1T are obtained through the thermal simulation test. The existing heating temperature design range is 950-1120°C. When the heating temperature is ≤1023°C, there is a steel billet in the heating process Insufficient austenitization

[0005] 2. When the existing pre-finishing and finishing-rolling inlet temperatures are controlled at the lower limit of the range, which is 910°C, the rolled piece will enter the two-phase zone for rolling, and mixed crystals will easily occur in the metallographic structure of the wire rod

[0006] 3. The surface metallographic structure of the ultra-low carbon steel wire rod produced according to the existing process is unstable, resulting in fluctuations in the mechanical properties of the wire rod

[0007] 4. Due to the fluctuation of the mechanical properties of the wire rod, after the downstream users draw the wire rod into steel wire, the surface hardness fluctuates greatly, which cannot meet the user's requirements stably

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