Is ASTM A36 steel round bar always weldable?
The ASTM A36 specification reads as follows:
When the steel is to be welded, a welding procedure suitable for the grade of steel and intended use or service is to be utilized. See Appendix X3 of Specification A6/A6M for information on weldability.
Appendix X3 of ASTM A6/6M states:
Weldability is a term that usually refers to the relative ease with which a metal can be welded using conventional practice. Difficulties arise in steel when the cooling rates associated with weld thermal cycles produce microstructures (for example, martensite) that are susceptible to brittle fracture or, more commonly, hydrogen-induced (or cold) cracking.
The relative sensitivity of steels to forming cold cracking microstructures is called hardenability and can be measured in a number of ways. Perhaps the most popular method of assessing this is by the carbon equivalent (CE) formula, which attempts to equate the relative hardening contributions of a steel’s constituent elements (for example, manganese, vanadium) to an equivalent amount of carbon, which is the most significant hardening agent. . . .
Though it is widely believed that low CE steels are immune to weld cracking problems, failure to consider these factors and others have resulted in weld or base metal HAZ (heat affected zone) cracks in such steels.
It is important to note that carbon equivalence is only a qualitative assessment of potential welding problems, and should never be solely relied on to ensure weld integrity. The proper use of welding specifications, coupled with the knowledge of actual construction conditions, must also be used.
As long as proper welding techniques are followed, you should have no issues welding to A36 steel.
Portland Bolt stocks A36 round bar in up to 3-1/2” on site and uses it to manufacture bolts meeting the ASTM specifications A307 and F1554 Grade 36. Larger diameters of A36 round bar are readily available. Contact one of our helpful team members for a quote.