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FINISHING AND COATING PROCESSES
Dhani Watanapongse, Inland Steel
D. Reinbold, Bethlehem Steel
The finishing and coating processes of the future will become continuous and will be flexible to meet the changing market needs. The objectives of this session of the Workshop were to:
Define which intelligent processing technologies can be utilized
Recommend specific directions necessary for the formulation of
The session consisted of two meetings designed to facilitate interaction between national experts and industry experts. The goal of the first meeting was to understand and assess the states of knowledge in intelligent processing; namely, product/process knowledge, process modeling, sensors, integrated process control, and artificial intelligence. The product/process relationships for steel substrates and coated steel were presented along with the needs for future improvements. Subsequent presentations were in sensor development, process modeling, and advanced control. The goal of the second meeting was to address the issues and resolutions that can enhance the success of future research programs to develop and apply intelligent processing technologies. Finally, summary and recommendations of the overall session were formulated and general consensus obtained at the conclusion of the session.
The major thrust that emerged was the need for integration of metallurgical knowledge with intelligent processing technologies; namely, sensor, process model, and advanced control. The development of identified sensors was perceived to be of the highest priority, since some sensors can have significant and immediate paybacks on the existing processes. Project team formulation, technology transfer, customer requirements were cited as the issues that must be addressed to enhance the success of future Research programs. Specifically, the group recommended that future efforts be focused on intelligent processing of hot-dip galvanizing process. The details of the summary and recommendations are as follows.
Although there is a wide range of sensor needs in the finishing and coating processes, five sensors listed below were identified as having highest priority. Further attempts to prioritize among the five or to define specific ranges and accuracy of the sensors were considered inappropriate by the group because sensor requirements must be specified as an integral part of process modeling and control system development. Attempts were made, however, to estimate the developmental time for the sensors based on current understanding of available principles and technologies. The five sensors are:
Continuous Measurement of Temperature of Strip [S]*
Highest priority should be directed to the exit point
On-line Measurement of Chemical Composition and Phase
Measurement of Surface Topography and Surface Chemistry of
“[S] Short Range 1-2 Years
[M] Medium Range 3-4 Years
[L] Long Range 5+ Years
Measurement of Lubricant Film Thickness (S]
Measurement of Mechanical Properties/Microstructure (S to L]
direct or predicted measurement of strength and formability in final product
Based on the discussion, it was believed that EMATS technology has been sufficiently demonstrated for R-value measurement to the point that on-line measurement of Rvalue can be realized within a relatively short time frame. For coating composition measurement, Energy Dispersive X-Ray Fluorescence has shown promise over conventional X-Ray Diffraction and Fluorescence techniques. Even though further investigation is needed in this area, the group believed that on-line measurement of coating composition can also be achieved within a short time frame. Laser-ultrasonic is another technology that has shown promise for phase-transformation and grain size measurements and odd-shape gauging. This technique provides excellent potentials for on-line remote sensing as well.
In general, product/process relationships for steel substrates are known. However, these relationships need to be further quantified and integrated with sensor information and expert knowledge to form working control systems, i.e., intelligent processing technologies. Engineered surfaces and microstructural engineering were cited as the important areas needing further modeling studies.
In the coating processes, much work is needed to understand and model coating adherence mechanisms for a range of coating materials, steel substrates, surface morphology, and processing parameters. In addition, press performance of coated materials in terms of stampability and powdering characteristics must be studied and modeled.
The significance of knowing the product end-use was emphasized by the industry experts. A concept of "component engineering" was introduced and discussed. This concept requires that customer manufacturing processes and required product properties be understood and the information utilized as the driver to product and process development. For example, formability, weldability, and paint appearance are as essential as corrosion resistance in a coated product for automotive applications.
SEMAT = ElectroMagnetic Acoustic Transducer, an ultrasonic device requiring no medium
to couple sound from transducer to moving sheet.
Specific modeling needs are:
Obtain the state-of-the-art of zinc coating and annealing
Development coating adherence and coating mechanism models.
Develop engineered product property models for coated and
Finally, it was noted that product and process knowledge is the limiting factor to process modeling, not the modeling techniques. As such, no new modeling tools were recommended by the group. However, a need was identified for fundamental studies to measure parameters (such as heat transfer coefficients) which are inputs to the various models.
Intelligent Processing was perhaps the most misunderstood subject of the discussion. For the purpose of this report, Intelligent Processing is defined as the integration of product/process expert knowledge, process models, and real-time sensors into an intelligent control system. As such, Intelligent Processing is not a replacement of expert knowledge, but rather a systematic approach to integrate a range of existing technologies into a working control system to achieve product consistency, design flexibility, and process optimization.
The group believed that Intelligent Processing has definitive roles in the finishing and coating processes, in terms of new product and process design and on-line process control. Specific recommendations are:
Develop real-time expert models for control to supplement
Develop implementable intelligent processing systems from hot
Since Intelligent Processing involves implementation and also a wide range of multidisciplinary backgrounds, the significance of project team formation, technology transfer, designed-in safety and maintenance were discussed at length. It was believed and recommended that a project team be formed to include from the start the industry, government, university, and equipment supplier, as shown in figure 1. There was some discussion on whether the customer should have input and should be a part of the project team. However, no resolution was reached. Finally, the incorporation of technology transfer from the beginning of the project was stressed as the key element to achieving a successful development and implementation of the technology
SUMMARY OF RECOMMENDATIONS
A formation of a broad-based and multidisciplinary project team to develop an implementable Intelligent Processing Technologies for the hot-dip coated product was recommended. The needs identified include the development of key on-line sensors, process models, and integrated process control systems. Both short- and long-term results can be expected, all of which can provide positive impacts to the existing products and processes. The developed technology will enable the processes to be responsive to changes in the marketplace. The technology will have applicability to the production of uncoated products as well. Finally, customer inputs will be essential to the success of the project. However, the proper role of the customers on the project must be further defined.
While the primary focus of the session was the needs of the steel industry, there was also a component directed to nonferrous metals. The relevancy of the recommendation to the copper and brass fabricating industry is shown in table 5 (submitted by B. G. Lewis of Olin Corporation) which suggests areas of need with a high degree of overlap between the two industries.
Prepared by: Dhani Watanapongse
A. Van Clark, Jr.