EXHIBIT 8.1

Principal subsidiaries

The following is a list of Ternium’s subsidiaries at December 31, 2023.

Company	Country of Organization	Main activity	Percentage of ownership at December 31,
			2023		2022		2021
Ternium S.A.	Luxembourg	Holding	100.00	%	100.00	%	100.00	%
Ternium Investments S.à.r.l.	Luxembourg	Holding	100.00	%	100.00	%	100.00	%
Ternium Internacional España S.L. (1)	Spain	Holding and marketing of steel products	100.00	%	100.00	%	100.00	%
Ternium Solutions S.A. (1)	Uruguay	Other services	100.00	%	100.00	%	100.00	%
Ternium Internationaal B.V. (1)	Netherlands	Marketing of steel products	100.00	%	100.00	%	100.00	%
Ternium USA Inc. (2)	USA	Manufacturing and selling of steel products	100.00	%	100.00	%	100.00	%
Ternium Argentina S.A. (3)	Argentina	Manufacturing and selling of flat steel products	62.57	%	62.57	%	62.49	%
Prosid Investments S.A. (4)	Uruguay	Holding	62.58	%	62.58	%	62.49	%
Ternium Mexico S.A. de C.V. (5)	Mexico	Manufacturing and selling of steel products	89.25	%	89.25	%	89.22	%
Las Encinas S.A. de C.V. (6)	Mexico	Exploration, exploitation and pelletizing of iron ore	89.25	%	89.25	%	89.22	%
Ferropak Comercial S.A. de C.V. (6)	Mexico	Scrap services company	89.25	%	89.25	%	89.22	%
Transamerica E. & I. Trading Corp. (6)	USA	Scrap services company	89.25	%	89.25	%	89.22	%
Galvacer Chile S.A. (6)	Chile	Distributing company	89.25	%	89.25	%	89.22	%
Ternium Gas México S.A. de C.V. (7)	Mexico	Energy services company	89.25	%	89.25	%	89.22	%
Consorcio Minero Benito Juarez Peña Colorada S.A.de C.V. (8)	Mexico	Exploration, exploitation and pelletizing of iron ore	44.62	%	44.62	%	44.61	%
Exiros B.V. (8)	Netherlands	Procurement and trading services	50.00	%	50.00	%	50.00	%
Servicios Integrales Nova de Monterrey S.A. de C.V. (9)	Mexico	Medical and Social Services	66.49	%	66.49	%	66.47	%
Ternium Internacional Nicaragua S.A.	Nicaragua	Manufacturing and selling of steel products	99.38	%	99.38	%	99.38	%
Ternium Internacional Honduras S.A. de C.V.	Honduras	Manufacturing and selling of steel products	99.18	%	99.18	%	99.18	%
Ternium Internacional El Salvador S.A. de C.V.	El Salvador	Manufacturing and selling of steel products	99.92	%	99.92	%	99.92	%
Ternium Internacional Costa Rica S.A.	Costa Rica	Manufacturing and selling of steel products	99.98	%	99.98	%	99.98	%
Ternium Internacional Guatemala S.A. (10)	Guatemala	Manufacturing and selling of steel products	99.98	%	99.98	%	99.98	%
Ternium Colombia S.A.S. (11)	Colombia	Manufacturing and selling of steel products	100.00	%	100.00	%	100.00	%
Ternium del Cauca S.A.S. (11)	Colombia	Manufacturing and selling of steel products	100.00	%	100.00	%	100.00	%
Ternium del Atlántico S.A.S (11)	Colombia	Manufacturing and selling of steel products	100.00	%	100.00	%	100.00	%
Ternium Procurement S.A. (11)	Uruguay	Marketing of steel products and procurement services	100.00	%	100.00	%	100.00	%
Technology & Engineering Services S.A. (11)	Uruguay	Engineering and other services	100.00	%	100.00	%	100.00	%
Ternium Brasil Ltda. (12)	Brazil	Manufacturing and selling of steel products	100.00	%	100.00	%	100.00	%
Tenigal S. de R.L. de C.V. (13)	Mexico	Manufacturing and selling of steel products	51.00	%	51.00	%	51.00	%
Soluciones Integrales de Gestión S.A. (14)	Argentina	Other services	100.00	%	100.00	%	100.00	%
Vientos de Olavarría S.A. (15)	Argentina	Renewable energy projects.	62.57	%	62.57	%	—
Usinas Siderúrgicas de Minas Gerais S.A. (16)	Brazil	Manufacturing and selling of steel products	23.30	%	—		—
Mineração Usiminas S.A. (17)	Brazil	Exploration, exploitation and pelletizing of iron ore	16.31	%	—		—
Soluções Em Aço Usiminas S.A. (18)	Brazil	Manufacturing and selling of steel products	16.05	%	—		—

Company	Country of Organization	Main activity	Percentage of ownership at December 31,
			2023		2022		2021
Usiminas Mecânica S.A. (19)	Brazil	Engineering and other services	23.30	%	—		—
Rios Unidos logistica e transporte de açõ Ltda. (19)	Brazil	Logistics and distribution of steel-derived products	23.30	%	—		—
Usiminas Internatioonal S.À R.L. (20)	Luxembourg	Holding	23.30	%	—		—
Usiminas Participações E Logística S.A. (21)	Brazil	Logistics and distribution of steel-derived products	17.48	%	—		—
Metalcentro Ltda. (22)	Brazil	Other services	23.30	%	—		—
Ternium Participaçoes S.A.em liquidaçao (23)	Brazil	Holding	—		100.00	%	100.00	%
Ternium Siderúrgica de Caldas S.A.S.(24)	Colombia	Manufacturing and selling of steel products	—		—		100.00	%
Impeco S.A. (25)	Argentina	Manufacturing of pipe products	—		—		62.49	%

(1) Indirectly through Ternium Investments S.à.r.l. Total voting rights held: 100.00%.<

(2) Since the second quarter of 2021, indirectly through Ternium Internacional España S.L. Total voting rights held 100.00%. Before t<hat, indirectly through Ternium Investments S.à.r.l. total voting rights was 100.00% in 2020.

(3) Indirectly through Ternium Internacional España S.L. Total voting rights held 62.57%.

(4) Indirectly through Ternium Argentina S.A. and Ternium Procurement S.A. Total voting rights held 100.00%.

(5) Indirectly through Ternium Argentina S.A. and Ternium Internacional España S.L. Total voting rights held 100.00%.

(6) Indirectly through Ternium Mexico S.A. de C.V. Total voting rights held: 100.00%.

(7) Indirectly through Ternium Mexico S.A. de C.V. and Tenigal S. de R.L. de C.V. Total voting rights held: 100.00%.

(8) Total voting rights held: 50.00%. The Company recognizes the assets, liabilities, revenue and expenses in relation to its interest in the joint operation.

(9) Indirectly through Ternium Mexico S.A. de C.V. Total voting rights held: 74.50%.

(10) Indirectly through Ternium Internacional España S.L. and Ternium Mexico S.A. de C.V. Total voting rights held: 100.00%.

(11) Indirectly through Ternium Internacional España S.L. Total voting rights held: 100.00%.

(12) Indirectly through Ternium Internacional España S.L. Total voting rights held: 100.00%.

(13) Indirectly through Ternium Internacional España S.L. Total voting rights held: 51.00%.

(14) Indirectly through Ternium Investments S.à r.l. and Ternium Internacional España S.L. Total voting rights held 100.00%.

(15) Indirectly through Ternium Argentina S.A. Total voting rights held: 100.00%.

(16) Indirectly through Ternium Investments S.à r.l., Prosid Investments S.A. and Ternium Argentina S.A. Total voting rights held 42,57%.

(17) Indirectly through Usinas Siderúrgicas de Minas Gerais S.A. Total voting rights held 29,80%.

(18) Indirectly through Usinas Siderúrgicas de Minas Gerais S.A. Total voting rights held 29,32%.

(19) Indirectly through Usinas Siderúrgicas de Minas Gerais S.A. Total voting rights held 42,53%.

(20) Indirectly through Usinas Siderúrgicas de Minas Gerais S.A. Total voting rights held 42,57%.

(21) Indirectly through Usinas Siderúrgicas de Minas Gerais S.A. and Mineração Usiminas S.A. Total voting rights held 31,97%.

(22) Indirectly through Usinas Siderúrgicas de Minas Gerais S.A. and Usiminas Mecânica S.A. Total voting rights held 42,53%.

(23) This company was dissolved as of January 2, 2023.

(24) This company was merged into Ternium Colombia S.A.S. as of November 30, 2022.

(25) This company was dissolved as of February 16, 2022.