Role of 3MA Steel Online-Monitoring (SOM) System for Strip Steel Industry

Machine-Material-Interaction: 3MA system integrated in the production line in order to monitor mechanical-technological material properties of steel strip during manufacturing

Situation of Strip Steel industry

Since the 1920s, steel has been the material of choice for automakers worldwide. Today, steel makes up around 65 % of an average automobile’s weight and is the backbone of the entire vehicle. On average, that is 900 kg of steel used per vehicle.

Strip steels are used in the automotive industry for car body constructions in order to reduce vehicle weight (and therefore the CO₂ equivalents) while maintaining or even improving safety and reliability of the construction, in short, for Stronger, Lighter and Safer Cars. However, the beneficial properties of advanced high-strength steel are much more sensitive to process variations than those of regular steel, raising the need for improved process monitoring and quality control. The same applies to other advanced steel qualities. So far, there is no comprehensive online testing solution accounting for all parameters of interest. For example, Yield Strength, Tensile Strength, Alongtion, Hardness, are still measured in the laboratory at randomly taken samples.

3MA Steel Online-Monitoring (SOM) System

Based on the 3MA measuring technique, several inline strip steel testing systems have been developed. They allow continuous contact-less determination of tensile (Rm), yield strength (Rp0.2), vertical anisotropy (rm), planar anisotropy (Δr), hardness and other material characteristics in the running strip (up to 300 m/min.).
■ Process-integrated 3MA (micromagnetic multiparameter microstructure and stress analysis) NDT Technique.
■ Robot-assisted inline-monitoring system for hardened and tempered steel strip.
■ Continuously self-adjusting positioning of the sensor by robots based on sensor-own signal generation and signal processing.
■ Continuous determination of Mechnical Properties, hardness and residual stresses within the steel strip.
■ Permanent readjustment of the process through independent extraction of relevant information by means of "cognitive sensor systems".

Potential for application

Usually, the mechanical properties of strip steel have to be assured by taking samples from the beginning and end of the strip rolled to a coil. These samples undergo time-consuming tensile tests, after which the coil is released. The time delay between sample collection and testing can reach up to several hours. During this time the finished coil can’t be shipped and has to be temporarily stored in the coil yard. A quick detection and reaction on deviations in the production process is not possible. For that reason, steel industry has a vital interest in inline testing mechanical properties of strip steel. 3MA is suitable for various kinds of steel used in all industries (automotive, aerospace, railway, metal production and processing, energy, ...)

The 3MA probe is fitted to a robot or into an electropneumatic manipulator, as shown in figures above. Usually, 3MA probe application is contact-free with a nominal lift-off from the strip between 1 and 8 mm. Typical applications of 3MA nondestructive testing methods along the value-added chain:
■ Materials characterization
■ Production-integrated testing
■ Component and assembly inspection
■ NDT for life-time monitoring

Benefits of Material Properties Online-Monitoring of Strip steel

■ Process integration, optimization, and control.
■ Condition statements concerning material properties, integrity of joint connections, ageing and wear of components and assemblies.
■ Determination of quality characteristics for life-time assessments.

For example, the plot of a continuous measurement of Yield strength Rp0.2 in a 2.5 km long strip is shown in figure above.

For more details, please contact LAB GAGES directly.

Based on the 3MA technique, an online testing system for the continuous determination of tensile strength (Rm), yield strength (Rp0.2), Hardness, and other mechanical–technological characteristics in a broad range of steel grades.