Preparation of Cold Rolled Steel Strip for Making High Quality Tape Measure

WANG Zhen; CHENG Xinli; XU Ruiliang; GE Zhendong; MENG Qian; LI Cheng

Abstract：High precision tape manufacturing of raw material 50 cold rolled steel strip steel purity and strip performance stability and other quality standards put forward extremely high requirements,through the"KR hot metal pretreatment combined with RH vacuum refining"technology,the carbon mass fraction of 0.52％to 0.58％,the total amount of phosphorus and sulfur impurities control within 0.023％,improve the purity of steel;Three stage temperature control is adopted in hot rolling,rough rolling increases the pass reduction,and the final rolling temperature and laminar cooling rate are precisely controlled to obtain a uniform hot rolling complex structure with grain size of 7.5-8.5.With the help of dynamic roll gap compensation technology,the total reduction rate can reach 70％-82％,and the 50 cold rolled steel strip which meets the demand of high precision tape manufacturing is developed by the cover annealing process.After the performance test,the average tensile strength of the steel strip is 518 MPa(fluctuation ≤ 20 MPa),the average yield strength is 365 MPa,the average elongation is 25.66％,the surface roughness Ra is less than 0.9 μm,and the annealing is uniform spherodized pearlite.In industrial production,the qualified rate of customers' trial batches has reached 98.9％,providing high-quality raw materials for the manufacturing of high-precision tape measures.