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A quantitative analysis method for martensite content in dual-phase steel

A quantitative analysis and dual-phase steel technology, applied in the field of steel materials, can solve problems such as unclear boundaries and errors, and achieve the effect of avoiding human subjective errors, avoiding calculation errors, and simple methods

Active Publication Date: 2018-03-09
BAOSHAN IRON & STEEL CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, since the boundary between the pattern mass distribution of martensite and ferrite is not obvious, there is a certain error in quantifying martensite based on the pattern mass distribution

Method used

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  • A quantitative analysis method for martensite content in dual-phase steel
  • A quantitative analysis method for martensite content in dual-phase steel
  • A quantitative analysis method for martensite content in dual-phase steel

Examples

Experimental program
Comparison scheme
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Embodiment Construction

[0040] Take a small piece of the dual-phase steel sample, and perform a complete annealing treatment (heating temperature is 950 ° C, hold for 30 minutes, and slowly cool with the furnace), to obtain an equilibrium ferrite structure;

[0041] Take a small piece of the same dual-phase steel sample and quench it. In order to obtain as much martensitic structure as possible, perform liquid nitrogen cooling after water quenching (-70°C, 1h);

[0042] Slowly heat the annealed sample at a rate below 0.01°C / s up to 950°C, and record the thermal expansion curve during the heating process;

[0043] Slowly heat the quenched sample at a speed below 0.01°C / s to 950°C, and record the thermal expansion curve during the heating process;

[0044] Slowly heat the dual-phase steel sample to be measured at a speed below 0.01°C / s up to 950°C, and record the thermal expansion curve during the heating process.

[0045] image 3 is the fitted full graph, Figure 4 It is to enlarge it locally for ...

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Abstract

The invention relates to the technical field of quantitative analysis of martensite content, and specifically discloses a method for quantitative analysis of martensite content in dual-phase steel. The method includes taking quenched, annealed, and three samples to be tested, heating and recording the thermal expansion curve under certain conditions, taking the temperature as the abscissa, and taking the length change rate as the ordinate, the thermal expansion curve in the quenched state, the thermal expansion curve of the sample to be measured, and the annealing The state thermal expansion curve intersects with the ordinate or the selected temperature T straight line at points M, S, and F, and the volume percentage of martensite is the cube of the ratio of the SF length to the MF length, that is (SF / MF)3. The present invention does not have the problem that martensite structure and ferrite structure are difficult to distinguish, and the obtained martensite length and ferrite length can be clearly and quantitatively obtained, which avoids human subjective errors and increases the accuracy of quantitative analysis .

Description

technical field [0001] The invention relates to the field of iron and steel materials, in particular to an analysis method for ferrite-martensitic dual-phase steel. Background technique [0002] The dual-phase steel composed of ferrite and martensite has the characteristics of low yield ratio and good processing performance, and has received more and more attention. Among them, martensite is the hard phase in the dual-phase steel, and its quantity has a great influence on the strength of the dual-phase steel. If the quantity is insufficient, the tensile strength of the dual-phase steel will not meet the standard. If the quantity is too large, the elongation of the dual-phase steel will be reduced. Aggravated, high intensity. Even, when the martensite content is low, as the martensite content increases, the failure strength of the dual-phase steel decreases; and when the martensite content is medium, the origin of the damage of the dual-phase steel changes from ferrite to ma...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01N25/00
Inventor 张所全焦四海姜洪生王全胜梁晓军
Owner BAOSHAN IRON & STEEL CO LTD