AISI 660, AMS 5731, ASTM A 638

AISI 660 overview:

AISI 660 is specifically designed for applications that require both high strength and good corrosion resistance in high temperature environments up to 704 ° C. The toughness of the AISI 660 cut section is very good. In fact, the notch fracture strength of AISI 660 is superior to other commercial alloys with similar high temperature properties. A major advantage of this material is that it can achieve precipitation hardening and strengthening effects through heat treatment.

 

AISI 660 chemical composition:

%	Ni	Cr	C	Mn	Si	Fe	Mo	Al	B	Ti	V
Min.	24	13.5					1.0		0.003	1.90	0.10
Max.	27	16.0	0.08	2.00	1.00	margin	1.5	0.35	0.010	2.30	0.50

 

AISI 660 physical properties:

Density: 0.2860lb / in3

 

AISI 660 solution treatment:

A286 can use the following two heat treatment methods:

1. Heat to 982 ° C, hold for 1 hour, then cool down quickly

2. Het to 899 ° C, hold for 2 hours, then cool down quickly

With the first method, after the material is aged, the cracking strength can be increased. The second method can improve toughness and hardness.

 

aging

Heat to 704-760 ° C, hold for 12-16 hours, and then air cool. The hardness after treatment is about 300BHN.

After solution treatment at 899 ° C, sometimes two rounds of precipitation hardening treatment are performed, that is, heating to 704/760 ° C, holding for 16 hours, then air-cooling to 649 ° C, holding for 8-12 hours, and then air-cooling. This treatment can increase notch cracking strength, while improving toughness and hardness. Dimensional change due to aging treatment-shrinkage of 0.001in / in

 

AISI 660 processing performance

Thermal processing

AISI 660 can be rolled and forged in the temperature range of 1038-1121 ° C. A286 is slightly more resistant to deformation during hot working than austenitic stainless steel. Do not forge below 927 ° C.

 

Cold working

A286 in solid solution can be cold drawn and cold formed. The processing difficulty is slightly greater than 316 and 310, and the cold work hardens quickly.

 

Special alloy materials commonly used in desalination:

Stainless steel: 317L, 1.4529, 254SMO, 904L, AL-6XN, etc.

Nickel-based alloys: Alloy 31, Alloy 926, Incoloy 926, Incoloy 825, Monel 400

Corrosion resistant alloy: NS112