What is the hardness of bolts after solution treatment?

As we discussed before on the identification of solution treated stainless steel bolts for hot runners and the comparison of 304/316 materials, there are specific norms for hardness after solution treatment for distinct materials:

Solution treatment of 304 stainless steel: Hardness ≤ HB187 (approx. HRB90), homogeneous structure, no residual processing stress

316 stainless steel after solution treatment: Hardness ≤ HB187, certain high-grade 316L can be as low as HB150, improved resistance to high-temperature creep.

Inconel high temperature alloy after solution treatment: hardness about HB200~250, with balance of strength and toughness, suitable for high load hot runner above 300℃.

Bolts of this hardness range are free of internal stress and are not subject to deformation and breakage under long-term high temperatures and are suited for hot runner installation requirements.