1. Scope

Keywords

Rationale

From the early days of B08, the committee has pursued developing material specifications that stress the performance of the coating system rather than process specification that stress the operating procedures to achieve the coating performance. Despite that difference, material specifications still must account for some processing conditions that can affect the overall performance of the plated article. Pre-plating stress relief and post-plating hydrogen embrittlement relief (both thermal treatments) are universally part of metal finishing processes that must be specified to ensure the base metal and coating will not fail in service. (This may seem a contradiction for a material specification as committee B08 envisions it, but it is necessary to achieve the performance of the coating since, generally, these requirements can’t be tested on the part after it is finished.) Originally, B08 put the stress relief and hydrogen embrittlement relief thermal treatment requirements along with the thresholds (Material UTS) for when they should be performed within each plating specification. Neither thermal treatment conditions or the threshold for when they should be used were universal across all types of plating, which resulted in over 90 different thermal treatments to consider when taken as a group. In the 1990’s, B08 created B849 and B850 guides on stress relief and embrittlement relief for iron and steel materials. Upon creation of these documents, the individual thermal treatments in the specifications were removed and pointed users to the guides for thermal treatment information. The thresholds for when thermal treatments were needed remained within each material specification and became mostly unified. With the advent of B849 and B850, the number of thermal treatments was reduced from 90+ to 16. At the time it was thought the new scheme would streamline the individual material specifications and reduce the amount of work needed to maintain them. Since that time, a short coming has been identified; the necessary thermal treatments for individual material specifications are not clearly defined for the plating processes they represent and are essentially unspecified. The guides only present users with thermal treatment classes that are open to interpretation and contain overlapping conditions which are confusing to understand and use. Another related issue not clearly defined in the material specifications is the necessity/requirements to test plating processes for hydrogen embrittlement. Most B08 material specifications recommend qualification of the plating process for hydrogen embrittlement relief per ASTM F-519, but often not set with any frequency requirement. This arrangement can lead to inconsistent results by the users since the requirement and frequency to perform the test is determined by the purchaser. (The testing is typically performed to monitor the process and keep operators aware the necessary steps to produce an acceptable plated article are all working correctly.) B08.02 conducted a complete review of B849 and B850 with the goal of clarifying and simplifying the pre and post plating thermal treatments in light of current practices and reducing conflicts between the material standards and these guides.