Exhibit 5.1

NORTH POINT Ÿ 901 LAKESIDE AVENUE Ÿ CLEVELAND, OHIO 44114.1190

TELEPHONE: +1.216.586.3939 Ÿ FACSIMILE: +1.216.579.0212

June 27, 2014

TimkenSteel Corporation

1835 Dueber Avenue, S.W.

Canton, Ohio 44706-2798

Re:        Registration Statement on Form S-8 Filed by TimkenSteel Corporation

Ladies and Gentlemen:

We have acted as counsel for TimkenSteel Corporation, an Ohio corporation (the “Company”), in connection with the TimkenSteel Corporation Savings Plan for Certain Bargaining Employees (the “Plan”). In connection with the opinion expressed herein, we have examined such documents, records and matters of law as we have deemed relevant or necessary for purposes of such opinion. Based on the foregoing, and subject to the further limitations, qualifications and assumptions set forth herein, we are of the opinion that the 100,000 common shares (the “Shares”), without par value, of the Company that may be issued or delivered and sold pursuant to the Plan will be, when issued or delivered and sold in accordance with the Plan, validly issued, fully paid and nonassessable.

The opinion expressed herein is limited to the laws of the State of Ohio, as currently in effect, and we express no opinion as to the effects of the laws of any other jurisdiction on the opinion expressed herein. In addition, we have assumed that the resolutions authorizing the Company to issue or deliver and sell the Shares pursuant to the Plan will be in full force and effect at all times at which the Shares are issued or delivered and sold by the Company, and that the Company will take no action inconsistent with such resolutions.

We hereby consent to the filing of this opinion as Exhibit 5.1 to the Registration Statement on Form S-8 filed by the Company to effect the registration of the Shares under the Securities Act of 1933 (the “Act”). In giving such consent, we do not thereby admit that we are included in the category of persons whose consent is required under Section 7 of the Act or the rules and regulations of the Securities and Exchange Commission promulgated thereunder.

Very truly yours,

/s/ Jones Day

ALKHOBAR Ÿ AMSTERDAM Ÿ ATLANTA Ÿ BEIJING Ÿ BOSTON Ÿ BRUSSELS Ÿ CHICAGO Ÿ CLEVELAND Ÿ COLUMBUS Ÿ DALLAS

DUBAI Ÿ DÜSSELDORF Ÿ FRANKFURT Ÿ HONG KONG Ÿ HOUSTON Ÿ IRVINE Ÿ JEDDAH Ÿ LONDON Ÿ LOS ANGELES Ÿ MADRID

MEXICO CITY Ÿ MIAMI Ÿ MILAN Ÿ MOSCOW Ÿ MUNICH Ÿ NEW YORK Ÿ PARIS Ÿ PERTH Ÿ PITTSBURGH Ÿ RIYADH Ÿ SAN DIEGO

SAN FRANCISCO Ÿ SÃO PAULO Ÿ SHANGHAI Ÿ SILICON VALLEY Ÿ SINGAPORE Ÿ SYDNEY Ÿ TAIPEI Ÿ TOKYO Ÿ WASHINGTON