Members of the National Union of Metalworkers marched in cities across the country, demanding a pay raise of up to 12 percent and better working conditions.
In Johannesburg city centre, thousands of workers clad in red waved sticks and branches from tree branches as they marched to the offices of an industry federation to hand in their demands.
The strike is expected to hit more than 10,000 metals and engineering firms that account for about four percent of South African economic output, according to economists at Citigroup.
Among the companies affected are multinationals BAE Systems and Bell Equipment. Industrial unrest could also spread to the power generation sector, where wage talks at state owned electricity monopoly Eskom are deadlocked.
The strike comes as yet another blow to South Africa’s beleaguered economy, which contracted in the first quarter after a five month platinum strike that was resolved only last week.
Last-gasp talks on Monday night between the metal workers’ union and industry leaders brokered by Labour Minister Mildred Oliphant failed to break the deadlock.
On Tuesday union leaders voiced their determination to see workers get a bigger share of South Africa’s economic pie.
“We are not backing down,” Zwelinzima Vavi, the secretary of the union federation COSATU, told workers.
“We are asking for a share in the economy of this country,” he said, urging workers not to give up on their demands.
“If they think we will tired after one week they are mistaken.”
Some fear another mass strike could push Africa’s most industrialised nation toward a recession that would increase widespread social unrest and already crippling unemployment.
The country’s credit rating was recently downgraded by Standard and Poor’s to one notch above junk status, a rating that would put South African government bonds off limits to many big institutional investors.
“Our economy has been seriously under-performing over the past few years and the situation has been worsening in recent times,” said Kaizer Nyatsumba, chief executive of industry umbrella group the Steel and Engineering Industries Federation of Southern Africa.
“The last thing that we need is a strike.”
Welder Sam Nyashe said he was not fazed by the prospect of losing wages during the strike.
“No matter how long it takes, it’s worth it. This is war,” he said.