That being said, not every plant makes every type of steel. Higher end steels are the types of steels that western manufacturers can compete on, so it is often what they specialize in.
This is a certifiable fact.
In general I'd say that some companies do this.
I did a quick search and found a few well-published incidents:
Kobe Steel (Japan)[1]
Japan Steel Works (Japan) - although this was faked inspection on manufactured components not raw steel[2]
Ossen Innovation Materials (China)[3]
Unsubstantiated reports of issues with companies from China, Germany, Italy and the US[4]
Le Creusot (France). Fake materials used in nuclear reactors[5]
[1] https://www.reuters.com/article/us-kobe-steel-scandal-ceo-id...
[2] https://www.asahi.com/ajw/articles/14617459
[3] https://www.rnz.co.nz/news/national/307694/steel-supplier-ha...
[4] https://www.eng-tips.com/viewthread.cfm?qid=304464
[5] https://www.steelavailable.com/en/counterfeit-steel-big-worr...