Tata and German steel manufacturer ThyssenKrupp have agreed the first stage of a deal to merge, BBC Wales understands.
They have been in negotiations since last year when Tata withdrew from a sales process to sell its entire UK operations, including Port Talbot – the largest steel works in the UK.
Tata’s £15bn pension scheme had been a major sticking point.
But it is understood an announcement will be made early on Wednesday.
It follows an agreement with workers and the support of the pensions regulators, which means Tata has distanced itself to a large extent from its pensions liabilities.
That has made a deal more likely between the two companies.
Almost 7,000 people are employed by Tata Steel across Wales, including more than 4,000 in Port Talbot.
In April, unions expressed fears a merger would be “high risk” and could lead to job josses.
IG Metall union, which represents metalworkers in Germany, is concerned the joint venture could pave the way for ThyssenKrupp to exit the steel business entirely.