Metal magnetic memory signals from surface of low-carbon steel and low-carbon alloyed steel

Abstract The way a piece or tool behaves in operation is determined by the quality of the material from which it is made, the precision of execution and heat treatment applied. In the present research, it is highlighted the differences that take shape after heat treating different materials (low carbon steel and high alloyed steel) including heating to dissimilar austenitic phases (880°C and 1020°C), holding for non-identical times, tempering at low temperature (260 °C) and then cooling by using separate cooling mediums (oil, air and water). The results show no noticeable increase in the hardness and mechanical properties for the low carbon steel after the heat treatment, but on the other hand, the high alloyed steel, reveals distinguishable changes in both hardness and mechanical properties. There is a close link between the structure, the parameters of the thermal processes and the properties that are desired so that future specialists have to assimilate the basic knowledge related to the phenomena that occur during a heat treatment but at the same time it is important to equip the companies with machines and measure devices, like a spectrometer.

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Stress State Detection Based on Metal Magnetic Memory Theory

Volume 5: High Pressure Technology, Nondestructive Evaluation, Pipeline Systems, Student Paper Competition ◽

10.1115/pvp2005-71271 ◽

2005 ◽

Author(s):

HaiYan Xing ◽

RiXin Wang ◽

MinQiang Xu ◽

JiaZhong Zhang

Keyword(s):

Magnetic Field ◽

Stress State ◽

Carbon Steel ◽

Material Strength ◽

Magnetic Memory ◽

Metal Magnetic Memory ◽

Low Carbon ◽

Medium Carbon ◽

Field Density ◽

Critical Damage

The metal magnetic memory (MMM) technology, a new nondestructive evaluation (NDE) method, is an effective means for early damage prediction. However, there is so much work to do, such as the relationship between the magnetic field density and stress state. This paper aims at finding out MMM signal characteristics of critical damage stress state by tension experiments. Comparisons between MMM testing and traditional NDE method are presented. The principle of MMM testing is investigated. Different materials, low carbon steal X70 and medium carbon Q235B, are detected on-line and off-line respectively. It is found that MMM signal rules are gradually increasing up to fluctuating on the verge of yield and sharp changing of magnetic polarity on the verge of fracture. With the increase in material strength, magnetic field density of low carbon steel X70 is lower than that of medium carbon steel Q235B. This offers fundamental study for the quantitative MMM testing of critical damage stress state.

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The Surface Weak Magnetic Signals of Low Carbon Steel under Cyclic Loads

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.298.197 ◽

2011 ◽

Vol 298 ◽

pp. 197-202 ◽

Cited By ~ 1

Author(s):

Jun Jie Yuan ◽

Wei Min Zhang

Keyword(s):

Carbon Steel ◽

Low Carbon Steel ◽

Magnetic Coupling ◽

Fatigue Loading ◽

Magnetic Memory ◽

Cyclic Loads ◽

Low Carbon ◽

Cyclic Stresses ◽

Coupling Behavior ◽

Potential Applications

The magnetization induced by applied cyclic stresses on low carbon steel samples was studied through experiments by using a high sensitive magnetic sensor. The stress-magnetic coupling under cyclic tensile stress was researched during static, cyclic and fatigue loading process respectively. The results indicate the consistency and also some contradiction with existing conclusions of metal magnetic memory theory or magneto-mechanical researches. It is put forward that the stress induce magnetization is dependent on both applied stress and micro structure abnormality in ferromagnetic materials. Then the potential applications of the stress-magnetic coupling behavior were proposed.

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