The steel strike which has threatened to immobilise the Australian car industry for the past three weeks is over.

Workers voted on Friday in favour of a compromise with management at BHP Steel's Western Port factory in Melbourne.

The plant supplies car factories, building contractors and other businesses.

The deal to settle the strike - called because the company was planning to shift some workers to part-time hours and contract out some maintenance - means that maintenance workers' job security is guaranteed.

It follows a riot police operation on horseback earlier this week, which forced back pickets sufficiently to get 400 tonnes of steel out of the plant.

Just in time

But even though the plant is coming back onstream, the bosses of Australia's car industry were keen to point out that their business risks losing its way altogether if industrial action continues.

Three strikes in less than a year have interrupted the just-in-time supply chains on which modern car plants rely.

The president of Ford Australia, Geoff Polites, said on Friday that any more stoppages could trigger a shift to overseas suppliers.

"We could go overseas right now - permanently," he told the Australian newspaper.

"I'm not saying we're going do, but the chances are we don't need to buy this steel in Australia any more. And if we move to buy it overseas it will never, ever come back."

Noting Ford's close relationship with Nippon Steel, Mr Polites said the marginal cost of importing from Japan was "a hell of a lot less than losing a couple of days of production".

But not everyone is willing to make such threats. The local arms of Toyota and Mitsubishi, while Japanese-owned, remain keen on retaining or even increasing local content.