6-K

FORM 6-K

U.S. SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

REPORT OF FOREIGN PRIVATE ISSUER

PURSUANT TO RULE 13a-16 OR 15d-16 UNDER THE

SECURITIES EXCHANGE ACT OF 1934

Dated April 22, 2021

Commission File Number 1-14878

GERDAU S.A.

(Exact Name as Specified in its Charter)

N/A

(Translation of Registrant’s Name)

Av. Dra. Ruth Cardoso, 8,501 – 8° andar

São Paulo, São Paulo - Brazil CEP 05425-070

(Address of principal executive offices)

Indicate by check mark whether the registrant files or will file annual reports under cover Form 20-F or Form 40-F.

Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(1): ____

Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(7): ____

Indicate by check mark whether by furnishing the information contained in this Form, the registrant is also thereby furnishing the information to the Commission pursuant to Rule 12g3-2(b) under the Securities Exchange Act of 1934.

If “Yes” is marked, indicate below the file number assigned to the registrant in connection with Rule 12g3-2(b): Not applicable.

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused the Report to be signed on its behalf by the undersigned, thereunto duly authorized.

Date:  April 22, 2021

EXHIBIT INDEX

Exhibit 99.1

GERDAU S.A.

Tax ID (CNPJ/MF): 33.611.500/0001-19

NOTICETO THE MARKET

Gerdau S.A. (“Company” or “Gerdau”) will resume steel production operations at the Araucária, Paraná unit in the second half of this year due to the positive scenario for steel demand in Brazil, especially in the construction, infrastructure and industry sectors. Investments to resume operations at the mill are around R$ 55 million.

The unit, with annual crude steel production capacity of 420,000 tons, has been in hibernation since 2014 and will gradually resume operations, adjusting its production volume to the evolution of the domestic market. As a result, approximately 300 new direct and indirect jobs will be created.

“We are optimistic about the bright outlook for the domestic market. By resuming production, the company aims to continue meeting the growing demand for long steel in Brazil, and to optimize the supply of products to customers throughout the country alongside existing capacities,” says Marcos Faraco, vice president of Gerdau.

São Paulo, April 22, 2021

Harley Lorentz Scardoelli

Executive Vice President

Investor Relations Officer