For the year, our free cash flow generation was positive overall at $168 million pre-pension contributions, free cash flow exceeded our full year guidance by 18%.
We ended the year with more than $950 million of total liquidity, including nearly $650 million of cash on hand.
We eliminated approximately $170 million of costs in 2020.
We expect total cost reductions to grow to at least $270 million over the next few quarters as actions implemented in the second half of 2020 reached their full run rate.
Importantly, we expect about $100 million of these cost savings to become structural, continuing to benefit ATI as we return to growth over time.
In 2021, our share of jet engine materials and components on key programs is increasing.
You may recall, we're exiting standard stainless sheet products by year-end 2021 as we redeploy our capital to high return opportunities.
Second, we're on track to exit 100% of standard value stainless sheet products by year-end 2021.
In the fourth quarter, sales of these products represented 17% of AA&S segment revenues down from 22% in full year 2019.
This investment of $65 million to $85 million spread over three years will be largely self-funded through working capital releases, triggered by the transformation.
Naval nuclear products in support of the U.S. Navy's increased long-term demand for new ships grew by nearly 50%.
Our fourth quarter oil and gas and chemical processing submarket sales dropped by more than 35%.
Sales to our specialty energy markets were more resilient declining only 6% versus the prior year.
We expect these negative trends to continue until vaccination programs reach critical mass.
For ATI, it started with 737 MAX challenges that carried over from 2019.
In fact, Q4 revenue increased 10% to $658 million versus Q3 levels.
Our adjusted EBITDA increased 39% to $23 million in Q4 from Q3 levels.
Adjusted earnings per share was a loss of $0.33 per share in Q4.
This was better than the optimistic end of our earnings per share guidance range, which was a loss of between $0.36 and $0.44 per share.
Speaking of cost reductions, in our early 2020 we announced targets to cut costs by between $110 million and $135 million for the year.
In the last earnings call, we shared a target of $160 million to $170 million of 2020 savings.
The final tally, reductions near the high-end of our guidance and nearly $170 million in 2020.
That means a run rate of $270 million to $180 million of cost reductions that will benefit full year 2021.
Those cost reductions, continue to contribute to favorable detrimental margins, which are below 30% for the third consecutive quarter.
We expect approximately $100 million of those reductions to be structural.
Our free cash flow was $168 million for full year 2020, well in excess of the top end of our guidance range of $135 million to $150 million.
We're extremely pleased that we closed 2020, with nearly $650 million in cash and more than $950 million of total liquidity.
We ended Q4 with managed working capital at 41% of revenue, down 1,000 basis points from the end of Q3, great progress.
Our goal is to reduce managed working capital for less than 30% of revenue over time.
We started 2020 with a CapEx forecast $200 million to $210 million.
Actual CapEx spend in 2020 totaled $1.37 million, 33% below the initial forecast.
We ended 2020 with a net pension liability of $674 million that's nearly $60 million lower than the opening 2020 level.
Strong pension asset performance and Company contributions in 2020 more than offset an 80 basis point decrease in discount rates.
Weakness in airframe materials will continue throughout 2021 consistent with our prior estimates.
We expect to Q1 2021 adjusted earnings per share loss of between $0.23 and $0.30 per share.
We expect to generate between $20 million and $60 million of free cash flow in 2021 prior to our required US defined benefit pension contributions.
Now CapEx; we plan to spend between $150 million and $170 million on capital investments in 2021.
As you know contributions to the US pension plans in 2020 were $130 million.
Due in part to strong 2020 pension asset returns required contributions to the US plans are anticipated to be $87 million in 2021, a reduction of more than $40 million year-over-year.
2021 pension expense will also decrease dropping $17 million year-over-year.
Pension expense will be $23 million in 2021, down from $40 million of recurring pension expense in 2020.
We will pursue our goal of returning working capital levels to 30% of sales as our key end markets recover.
However we can say that we expect to pay between $10 million and $15 million in cash taxes during the year.

Summary:
We expect total cost reductions to grow to at least $270 million over the next few quarters as actions implemented in the second half of 2020 reached their full run rate.
In 2021, our share of jet engine materials and components on key programs is increasing.
You may recall, we're exiting standard stainless sheet products by year-end 2021 as we redeploy our capital to high return opportunities.
We expect these negative trends to continue until vaccination programs reach critical mass.
In fact, Q4 revenue increased 10% to $658 million versus Q3 levels.
Adjusted earnings per share was a loss of $0.33 per share in Q4.
Weakness in airframe materials will continue throughout 2021 consistent with our prior estimates.