According to the news, the work stoppage at the company’s Port Talbot and Llanwern, Newport, locations will start on July 8.
The strike would “severely impact” the company’s UK operations, according to the union.
It is a reaction to Tata Steel’s intention to close its blast furnaces in South Wales, endangering 2,800 jobs.
According to the union, this would be the first strike by UK steelworkers in over 40 years.
In April, members approved the change with a vote.
Earlier this week, there was a prohibition on overtime and personnel working to rule as part of industrial action that stopped short of a walkout.
“Tata’s workers are not just fighting for their jobs – they are fighting for the future of their communities and the future of steel in Wales,” stated Sharon Graham, general secretary of the union.
“Our members will not stand by while this immensely wealthy conglomerate tries to throw Port Talbot and Llanwern on the scrap heap so it can boost its operations abroad.”
“The strikes will continue until Tata halts its disastrous plans,” she continued.
“Unite is backing Tata’s workers to the hilt in their historic battle to save the Welsh steel industry and give it the bright future it deserves.”