1910	June	The Tobata Foundry Co., which later became the Tobata Works, established. This was the first modern malleables manufacturing facility in Japan. Later, fittings, small-scale pig iron rolls, and cast steel product manufacturing facilities were added.
1917	July	Teikoku Foundry Co., which later became the Wakamatsu Works, established to initiate production of a variety of rolls in Japan. Purchased in 1926 by the Tobata Foundry Co.
1922	December	Kizugawa Manufacturing, which later became the Kuwana Works, established as a plant specializing in fittings. Purchased in 1926 by the Tobata Foundry Co.
1929	November	The Tokyo Manufacturing Plant of the Tobata Foundry Co., which later became the Fukagawa Works, established to manufacture malleables for use in the automobile industry.
1934	February	Yasugi Steel Manufacturing, which later becomes Yasugi Works, is merged by Tobata Foundry Co. (Yasugi Steel Manufacturing was created as the result of the Unpaku-Steel Limited partnership in 1899 and purchased by Tobata Foundry Co. as a subsidiary in 1925).
1935	November	Name of the Tobata Foundry Co. changed to Kokusan Industries, Ltd.
1937	May	Kokusan Industries, Ltd. purchased by Hitachi, Ltd.
1956	April	Hitachi Metals Industries, Ltd. established (Capital: ¥1 billion provided by Hitachi, Ltd.)
	October	Hitachi, Ltd., transferred its metals business and five plants to Hitachi Metals Industries, Ltd. (Tobata, Fukagawa, Kuwana, Wakamatsu, and Yasugi), and business activities began.
1961	July	Kumagaya Works established
	August	Over-the-counter trading of shares begun
	October	Listed on the second sections of the Tokyo and Osaka stock exchanges
1962	August	Upgraded listing to first sections of the Tokyo and Osaka stock exchanges
1965	November	Hitachi Metals America, Ltd., established in the United States
1967	January	Merged with Hitachi Metals, Ltd., to change par value of shares and company name
1970	October	Hitachi Metals Europe GmbH established in Germany
1979	February	Hitachi Metals Singapore Pte. Ltd. established in Singapore
1995	October	Merger with Hitachi Ferrite, Co. Ltd.
2001	April	Implementation of officer system and company system
2003	June	Adopts Company-with-Committees Structure
2003	August	Purchased the Amorphous Metals Business Division of Honeywell International Inc.
2003	October	Transfered Hitachi Metals' water treatment business to Hitachi Plant Engineering & Construction Co., Ltd.
2004	April	NEOMAX Co., Ltd. became a consolidated subsidiary of Hitachi Metals
2005	April	Soft Magnetic Materials Company Established
2007	April	Merger with NEOMAX Co., Ltd.
2011	April	Metglas Yasugi Works established
2012	April	Saga Works established
2013	July	Merger with Hitachi Cable, Ltd., Cable Materials Company established
2014	July	Acquisition of Shares of MMC Superalloy Corporation. Hitachi Metals MMC Superalloy, Ltd. became a consolidated subsidiary of Hitachi Metals
2014	November	Waupaca Foundry, Inc. became a consolidated subsidiary of Hitachi Metals
2015	January	Hitachi Metals Korea Co., Ltd. is established.
2015	November	Diehl Tool Steel, Inc., a wholly owned tool steel distribution subsidiary in U.S., is established.
2016	February	Acquisition of shares in U.S. medical equipment components companies, HTP-Meds, LLC and Hi-Tech Machine and Fabrication, LLC.
2016	September	Neodymium-Iron-Boron magnets manufacturer Hitachi Metals San Huan Magnetic Materials (Nantong) Co., Ltd. is established in China.
2017	April	Global Research & Innovative Technology Center (GRIT) is established.
2018	April	Hitachi Metals MMC Superalloy, Ltd. merges with Hitachi Metals. The Okegawa Works is established.
2019	April	Reform the 4 internal companies into 2 business divisions.
2023	January	Hitachi Metals changed its name to Proterial.