Do you know the Difference Between Macro-Alloy and Micro-Alloy Steels?
Alloy steel can be micro-alloyed or macro-alloyed steel, and the difference includes the other types of metals included in the process, as well as the amounts of those metals. Macro- and micro-alloyed steels also differ when it comes to performance, strength, and even cost. With micro-alloyed steel, there are small amounts of metals such as zirconium, niobium, vanadium, boron, titanium, molybdenum, and rare-earth metals. Usually, the percentage of these metals is around .05% to .15%. Without heat treatment, micro-alloyed steels have a strength that is between 275 and 750 MPa, or 40 and 110 KSI.
More About Micro-Alloyed Steel
Other features of micro-alloyed steel include good weldability, excellent wear resistance and fatigue life, and the possibility of improving the weldability of the metal by reducing carbon content. Micro-alloyed steels are also not quenched and tempered, you also do not need to strengthen them or relieve any stress. This being said, a disadvantage to micro-alloyed steel is that toughness and ductility are not as good, in part because it is not quenched and tempered. Quenched and tempered (Q&T) steels always have more ductility and are tougher than micro-alloyed steels.
What About Macro-Alloyed Steel?
Macro-alloyed steel, also called high-alloy steel, has higher chromium content. It is more expensive than micro-alloyed steel and it has high levels of manganese and carbon, which results in an austenitic quality and therefore, it cannot be hardened by heat and it is essentially non-magnetic. If you expand the chromium content, you get better protection from erosion, and if metals such as molybdenum and nickel are added, you get added benefits such as more protection from consumption and much better formability. Both micro- and macro-alloyed steels have their pros and cons and are valuable with their respective end use applications.
