Document and Entity Information - shares	6 Months Ended
	Mar. 31, 2018	May 03, 2018
Document and Entity Information
Entity Registrant Name	HAYNES INTERNATIONAL INC
Entity Central Index Key	0000858655
Document Type	10-Q
Document Period End Date	Mar. 31, 2018
Amendment Flag	false
Current Fiscal Year End Date	--09-30
Entity Current Reporting Status	Yes
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		12,520,020
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	Q2