Q: We have a drawing for a 17-4 1″ bolt that we would like to order which can be heat treated to H900 – H1050. Are there any heat treat conditions that we should avoid? I’ve heard H900 can lead to sudden failure? Is this true?
A:
With the 17-4PH heat treat conditions, you are trading off elongation for higher strength (and hardness). So, an H900 heat treat would be stronger – but have slightly lower elongation and slightly less toughness compared to an H1050 heat treat. So, H900 may be more prone to failures due to shock loads.
Our advice is always to go with the highest heat treat condition allowable to maximize toughness.