Arconic Inc. will freeze pension plan contributions for U.S. workers and instead make contributions to a 401(k) plan for employees.

The company said the freeze only applies to the accrual of benefits for about 7,900 U.S. employees. Benefits accrued through March 31 will still be available upon retirement. The new policy goes into effect April 1.

There is no impact to retirees already collecting benefits.

The maker of aluminum parts for the aviation and automotive industries was created after Alcoa split into two companies in 2016. It expects a liability decrease of about $140 million from the pension freeze.

Former CEO Klaus Kleinfeld resigned abruptly in April 2017 after he sent a letter containing veiled threats to Elliott Management founder Paul Singer. Elliott owns more than 10 percent of Arconic.