| Cover | Jun. 27, 2024 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Jun. 27, 2024 |
| Entity File Number | 001-33288 |
| Entity Registrant Name | HAYNES INTERNATIONAL, INC. |
| Entity Central Index Key | 0000858655 |
| Entity Tax Identification Number | 06-1185400 |
| Entity Incorporation, State or Country Code | DE |
| Entity Address, Address Line One | 1020 West Park Avenue |
| Entity Address, City or Town | Kokomo |
| Entity Address, State or Province | IN |
| Entity Address, Postal Zip Code | 46904-9013 |
| City Area Code | 765 |
| Local Phone Number | 456-6000 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Stock, par value $0.001 per share |
| Trading Symbol | HAYN |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | false |
