Requirements for ferrite content in duplex steel
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I encountered a problem today: our company imported a batch of duplex steel plates (material ASME A240 UNS S32750). Measurements using a ferrite meter showed that the ferrite content was around 38% (while the FEH values specified in the warranty certificate were 49% and 51%). Our management believes that the ferrite content of these steel plates is not up to standard. I would like to ask everyone what level of ferrite content in duplex steel is considered acceptable In which standard are clear specifications for sheets of material provided? (I checked several standard references; they all mention duplex steel and cast iron components – are there any references related to sheets?) ）
General standards do not specify exact content limits; it is usually between 40% and 60%. The values given in the warranty certificate are too absolute; it’s impossible to guarantee that all areas of the entire panel are uniform.
In duplex steel, the contents of ferrite and austenite should both be within the range of 40% to 60%. For ordinary plates and pipes, the ratio of these two phases is generally around 50%, while in welded joints this ratio should be kept between 40% and 60%. It is recommended to measure the ferrite content at multiple points.
This parameter is included in the domestic standards for duplex steel, but since your steel sheet is imported, it’s difficult to determine
All of this is mentioned in the literature. Are there any standards or relatively authoritative regulations?
Which standard is it? Studying*
I found it online; it only states that it’s A890. The A890 specification specifies that the ferrite content is 30-60%. But castings. Have foreign countries confused billets with castings? ;P
According to 6.8.2 of GB/T 24511-2017, at the request of the purchaser and as specified in the contract, phase proportion tests for austenite-ferrite stainless steels shall be carried out in accordance with GB/T 13305, with the ferrite content required to be between 40% and 60%.
GB/T 24511-2017
The warranty for steel materials usually includes two sets of data: the first set represents the values specified by the standards, while the second set represents the values measured by the factory
Putting aside the regulatory requirements, the difference between your actual test value and the value stated in the warranty certificate is quite large. What exactly is causing this discrepancy? 1. Is there one that made a mistake? 2. Is there a company whose testing equipment is not up to standard? It must not be the version from the manufacturer – number 3. The testing methods of the two companies are different; number 4. The testing locations differ, which leads to discrepancies. Number 5: @ShuTong @RedLee_ZZHI @ZhiZheMing @ZhongYuanRen