Quick detection and evaluation method of harmful precipitated phase in two-phase stainless steel

Abstract

The invention discloses a quick detection and evaluation method of harmful precipitated phase in two-phase stainless steel. The method comprises the following steps: S1, determining harmful phase content in two-phase stainless steel at different sensitization time by using a counting method and a ferrite instrument, and drawing two results as a relation graph; S2, determining the hardness of the two-phase stainless steel with different harmful phase contents, and drawing a relation graph of the harmful phase content and the hardness; S3, respectively performing solution corrosion and electrolytic corrosion on the two-phase stainless steel with different harmful phase contents, and observing the similarity of the metallographic structure of two corrosion methods, thereby acquiring a metallographic atlas; and S4, comparing with a field detection result according to relation graphs and the metallographic atlas, judging whether the harmful phase is existent in the two-phase steel in site,and estimating the volume fraction of the harmful phase. By establishing the correlation between an accurate laboratory method and an operable field method, whether the harmful phase is existent in the two-phase steel base material can be quickly judged in site, the method is simple and practical, and the time and cost for sampling to the laboratory to analyze are saved.

Description

technical field [0001] The invention relates to the field of detection of harmful phases in metal materials, in particular to a rapid detection and evaluation method for harmful precipitated phases in duplex stainless steel. Background technique [0002] Duplex stainless steel contains about 30%-50% ferrite and 50%-70% austenite, and has good mechanical properties and corrosion resistance. The σ phase is a brittle and hard intermetallic compound with a tetragonal crystal structure and rich in Cr and Mo. The precipitation of the σ phase will seriously damage the mechanical properties and corrosion resistance of duplex stainless steel. Duplex stainless steel will precipitate σ phase when exposed to 600-1000 °C for a period of time. The σ phase is usually formed by the eutectoid decomposition of ferrite, so the precipitation of the σ phase will consume the ferrite content. Many test results show that the precipitation of σ phase will definitely be accompanied by pitting corro...

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Problems solved by technology

At present, the standard test methods used to detect the precipitation of σ phase mainly include sodium hydroxide electrolytic erosion test, Charpy impact test, and ferric chloride corrosion test. On-site analysis without damage on the equipment body is not conducive to quickly determining whether there is sigma phase precipitation on site, which will lead to economic losses caused by production discontinuity

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