Enamel steel for cold rolling water heater and manufacturing method thereof

Abstract

The invention discloses enamel steel for a cold rolling water heater and a manufacturing process thereof. The enamel steel for cold rolling water heater comprises components as follows in percentage by weight: C: 0.01%-0.08%. Si: less than or equal to 0.03%, Mn: 0.10%-0.60%, P: less than or equal to 0.02%, S: 0.003%-0.02%, N: 0.001%-0.006%, AIs: less than or equal to 0.04%, Ti: 0.02%-0.12%, and the balance of ferrum and unavoidable impurities, wherein excess Ti content in steel is equal to Ti-(4*C+3.43*N=1.5S) which is less than or equal to 0. The manufacturing process is characterized in that the heating temperature of billet steel is 1160-1300 DEG C; the hot rolling finish rolling temperature is 850-950 DEG C; the coiling temperature of steel plates is 660-760 DEG C; the cold rolling draft is 60%-80%; the annealing temperature is 760-880 DEG C; the temperature preservation time is 60-200s; rapid cooling speed rate is 15-45 DEG C/s, planishing elongation is 0.7%-1.8%; and surface roughness is 0.7-1.9 micrometres. The invention has the advantages of excellent formability, enamel-spreadable property, pressing resistance, weldability and fish-scaling resistance, stable yield strength after enamelfiring, less cost increase, stable effect and significant economic benefits.

Description

technical field [0001] The invention belongs to the field of steel rolling, and is particularly suitable for cold-rolled enamelled steel for water heaters produced by cold-rolling continuous annealing and a production method thereof. Background technique [0002] In recent years, in the production of water heaters in our country, more and more enamel inner tanks are used. Due to its superior performance in anti-corrosion, the enamel inner tank is replacing other inner tanks and becoming the main force of the water heater inner tank. [0003] The tank of the water heater is composed of three parts: the barrel body, the upper and lower heads, or two parts, the upper and lower heads. Among them, the upper and lower heads are formed by stamping, and the barrel is formed by coiling. Pretreatment, enamelling and sintering are carried out after welding. Not all steels are suitable for enamelling. The water heater steel plate should meet the following factors: enamellability, for...

AI Technical Summary

Problems solved by technology

This type of steel is mainly composed of ferrite, cementite and a small amount of pearlite. After sintering at a temperature of 830-860°C for 7-15 minutes, the cementite and a small amount of pearlite in the steel will disappear. After heat treatment, the ferrite grains in the steel will grow up and the grain size will increase. The yield strength of the steel will decrease obviously after sintering, and the decrease in yield strength will directly affect the quality of the enamel liner. Pressure resistance, the pressure resistance of the steel plate also affects the enamel performance of the steel plate, and the enamel steel with poor pressure resistance is easy to cause the enamel to peel off

[0005] Because, at present, the yield strength of SPCC cold-rolled plate cannot reach 300MPa before leaving the factory. Therefore, the problem in water heater manufacturers is that the material is soft and the yield strength is insufficient. At the same time, the high carbon content in the steel will also affect the welding performance. Causes unstable or poor welding performance, affecting water heater pressure test results and scale explosion resistance

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