Improving preventive measures to ensure the stability of technology and quality parameters of flat rolled products

Abstract

In the work, on the basis of
combining the tools of ISO and Lean systems, the methodology for continuous optimization of the
technology and improvement of rolled products quality has been proposed. The proposed
methodology is applied to products that have passed the development stage and are produced in
industrial volumes, and can also be used by partner companies that modify the products of the
manufacturing company in order to acquire additional added value. It is proposed to use colored
markers to visually assess the condition and determine the levels of the technological process when
establishing the limitations of the technological parameters. The improved rolled products quality
management methodology is based on the use of the Deming cycle and includes the use of analysis
tools such as the Ishikawa diagram, the Pareto method, the distribution diagram and the 3σ Rules,
and the Shukharts control cards. For the first time, the differentiated solutions have been proposed
for further treatment of products manufactured with different levels of technology stability and
quality. The effectiveness of this methodology has been verified on the basis of the actual data on
the complex of mechanical properties of 14 mm plates made of steel grade K60, produced according to the thermomechanical rolling regimes at plate mill 3600 of AZOVSTAL IRON &
STEEL WORKS. The comparative calculation has been made between the quality level according
to the actual data and the level calculated according to the proposed methodology. It has been
established that the introduction of the proposed methodology will reduce the standard deviation of
the yield strength, tensile strength and elongation of the investigated rolled products by 44 %, 31 %
and 46 %, respectively. This indicates a general increase in the stability of the technology and
quality. The proposed methodology allows us to provide quality parameters within the limits
established by regulatory documents, and also allows us to control their level to obtain the best
economic result within both ISO and Lean systems.