Senator Gallagher denies the fund would be inflationary, saying it would instead unlock industry's potential.
"The opportunities are real," she told AAP on Wednesday.
"For some areas where they're going to need an extra bit of help or no-interest loans ... their industry depends on it."
Senator Gallagher said the consequences of failing to shore up domestic manufacturing became evident during the pandemic.
"You have supply chain problems, you have no capacity to manufacture things that you desperately need, and we want to change that," she said.
Labor took its plan to establish a National Reconstruction Fund to the federal election last year, pledging to give businesses access to finance in a bid to improve innovation in areas including transport, medical science and defence.
Opposition industry spokeswoman Sussan Ley took aim at the fund, which she said was bad for taxpayers and the economy.
"The government is once again rushing through flawed legislation and trying to side-step parliamentary scrutiny," she said.
"This is not an appropriate way to establish a $15 billion government investment body."
The coalition is also concerned the structure gives too much discretion to the minister to make board appointments and the funding model could distort the investment market.
But Treasurer Jim Chalmers says the fund is needed because Australia's manufacturing base isn't secure enough, including throughout the energy sector.
"All of that meant that our economy wasn't resilient enough at a time of extreme global volatility and this puts upward pressure on inflation," he told parliament on Wednesday.
"It's why making our supply chains more resilient and such an important part of our efforts to address the inflation challenge."
Nationals senator Bridget McKenzie said the fund fell short of what it needed to do.
She said it was disappointing the government was not backing the Australian space industry and she wanted to see real investment in rural and regional communities.
"We are still considering the amendments we will make to this bill, but as it is now we cannot support it," she said.
That means the government will need the support of the Greens and two crossbenchers in the Senate.
