This is why you need to understand material properties

It might help to not grind the welds, in the aviation world, you leave the welds visible because it is stronger. They are less likely to crack.
Its not the weld. Its the heat that changes the properties of the alloy. At least on my airframe no welding is allowed anymore.
 
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I was refering to the middle pic of the steel one. Good hiloc installation would eliminate the need for welds, or proper oven heat treat would reduce the cracking...
 
Its not the weld. Its the heat that changes the properties of the alloy. At least on my airframe no welding is allowed anymore.
Apache's are in their own world, Boeing will spend $10K milling a 6" thick billet block to keep from riveting a bent tab on to a panel. Besides Boeing gave up a lot of welding to subcontractors...because thier environmental guy was too lazy to do the work to document the flux usage.
 
I was refering to the middle pic of the steel one. Good hiloc installation would eliminate the need for welds, or proper oven heat treat would reduce the cracking...
Yes, heat treat would be better after fab. The problem with that is if you want to do more than one bumper at a time per batch, you have to build a fixture to bolt the bumper to in order to prevent warping from the relieved and induced stresses. The cost of those fixtures has to be amortized into the total run of bumpers and you have to analyze the cost versus benefit to the end user of doing so.

It is easier to just understand what is going to happen, design around that, keep the costs as low as is feasible for the most benefit to the end user and go have fun.

It is possible to solve every problem by throwing lots of money, tech, and skill at it. Few of those are a good return on the investment of same with regard to crap that is going to get drug through the rocks.
 
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Yes, heat treat would be better after fab. The problem with that is if you want to do more than one bumper at a time per batch, you have to build a fixture to bolt the bumper to in order to prevent warping from the relieved and induced stresses. The cost of those fixtures has to be amortized into the total run of bumpers and you have to analyze the cost versus benefit to the end user of doing so.

It is easier to just understand what it going to happen, design around that, keep the costs as low as is feasible for the most benefit to the end user and go have fun.

It is possible to solve every problem by throwing lots of money, tech, and skill at it. Few of those are a good return on the investment of same with regard to crap that is going to get drug through the rocks.
In my world we do a lot of heat treated parts, but finish machining (or grinding) always comes after heat treat. 440C doesn't like to be machined after heat treat so we grind for flatness/parallel. 17-4 or 4340 isn't as hard so we machine after. Warping and dimensional changes during heat treat are a huge problem so we finish machine after. Car parts just can't afford the extra manufacturing cost and inspection we have to deal with.