U.S. Steel Corp. reported third-quarter earnings in 1978 yesterday that were $63.6 million higher than the same period last year, but the firm said that was less than expected.

The nation's largest steelmaker said income for the quarter was $88.8 million ($1.56 per share) on sales of $2.8 billion.

In the same quarter of 1977, income was $25.2 million (30 cents) on sales of $2.4 billion.

For the first nine months, U.S. Steel said it earned $147.4 million ($1.74) on $8.2 billion in sales, compared with income of $128.9 million ($1.54) on sales and revenue of $7.2 billion in the same period last year.

"Income for the third quarter was below the corporation's expectation, even though both steel and nonsteel operations had improved results compared with last year's third quarter," a company statement said.

Among the factors were increased repair and maintenance costs and a strike at the Norfolk and Western Railway, which serves a number of U.S. Steel facilities.

Borden Inc., producer of foods and chemicals, had record earnings for the third quarter and nine months.

The company earned $34.94 million or $1.12 a share for the quarter, 3 percent up on the $33.94 million or $1.09 a year earlier. For the nine months the company had a 4.5 percent year-to-year gain - to $1.02.84 million or $3.30 a share from $93.38 million or $3.16 a share.

Net income for the Times Mirror Co. for the third quarter of 1978 was $3.13 million (91 cents per share) compared with $25.9 million (74 cents) in the same period of 1977, it was disclosed yesterday.

Board Chairman Franklin D. Murphy said revenues for the 12-week period ended Oct. 8 were $352 million, compared with $279.5 million in the prior year.

Net income for the 40 weeks ended Oct. 8 rose 34 percent and totaled $94.6 million ($2.73) versus $70.7 million $2.03) in the first three quarters of 1977.

Revenues for the 40 weeks increased to $1.06 billion from $830.5 million in 1977.