Lork ASTM A564 Type 630 H1150 Stainless Steel Bar for Aerospace Components 17-4pH Rod

Weldability

This grade has a good weldability and doesn't normally need preheating, but welding design should be well evaluated in order to avoid situations prone to generate stress. In short, small sections could be welded in the solution treatment condition followed by an aging; large or heavy sections require a high temperature aging or overaging obviously followed by a new solution treatment (cond. A) and an aging.

Corrosion Resistance
This grade has the same general resistance corrosion as 304 but better than the group of standard martensitic 400 series. However, solution treatment (cond. A) without aging should be avoided. For maximum resistance to Chloride stress corrosion cracking, it should be aged at a higher temperature, not less than 550-580°C. In Sulfide aggressive environments, age at 620° C or overage. The same choice should be done in the case of situations or environments prone to cause H-embrittlement. It should also be noted that for this grade, as for every kind of stainless steel, surfaces should be free of contaminants and scale, and passivated for optimum resistance corrosion.

Cold Working
This grade has a limited cold deforming capacity in the annealed condition (cond.A) due to untempered Martensite. More severe cold working requires aging at the highest temperature or overaging. For restoring or increasing mechanical properties, such as Tensile Rm, a new solution treatment (cond.A) followed by a suitable aging temperature should be carried out.

Hot Working
Ingots or large forgings require a suitable preheating in order to avoid thermal cracking. Avoid overheating and improper cooling. Large forging bars should be equalized at 1030 -1040°C in the heating furnace prior to cooling. Both small or large forgings, rolled rings or bars must be cooled under 30°C after solution treatment (cond. A) in order to complete the transformation of martensite, obtaining both a good structure and mechanical properties after aging. It is useful to point out that a certain amount of Ferrite could be in the V174 structure.