ASTM A Class II Type B high chrome white iron is used in operating environments where abrasion and impact are the wear mechanisms. ASTM A standard has issued the chemical and hardness requirements for abrasion-resistant cast iron material grades, type A, B, C, D. ASTM A – Free download as PDF File .pdf), Text File .txt) or read online for free. Nihard.
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High Chrome White Iron – Abrasion Resistant Cast Irons
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Click Here to join Eng-Tips and talk with other members! Join your peers on the Internet’s largest technical engineering professional community. It’s easy to join and it’s free. Register now while it’s still free! Close this window and log in. Are you an Engineering professional? By joining you are opting in asgm receive e-mail. Promoting, selling, recruiting, coursework and thesis posting is forbidden. A machine shop has reported that some castings we sent for machining are harder than our drawing specifies.
We are having an issue machining the parts. We anticipated HB, which is 51 to 52 Rockwell C.
Then we would harden it after machining? For The shorter, simpler part we called for an as cast asrm of HB. The longer, more complicated part calls for the part to be annealed to HB.
I guess we specified the current parts to be as cast HB. We have approached the foundry to answer questions about softening and heat treating options.
ASTM A532 Class III Type A High Chrome Wear Resistant Material Castings
I foresee problems with distortion and perhaps even cracking of the finish machined parts. The castings already are distorted enough to require dimensional compromises.
My question is, can high chrome cast iron be “heat treated” to re-harden to HB after annealing or even tempering to ? Some of atm curves in the “Abrasion Resistant Cast Iron Handbook” suggest some high chrome irons can end up with vastly different hardnesses even after tempering to the same temperature, depending on retained austenite.
We used to stress relief anneal cylinders asrm we cast, we made sure to stay sub-critical. We were casting our own and kept retained austenite very low. You need to check on the current structure, and perhaps do some trials. Re-hardening is not advised as parts break easily. There is no issue involved. What is the part under consideration.
Abrasion resistant cast irons to ASTM A Standard
I have done slurry pump parts and grinding rolls. Hi arunmrao, attached is an image of the part in question, already cast and Atsm ish, and needing machining of several features.
About 4 feet mm long.
About 2 feet mm diameter. A little less than 1 inch in thickness aa532 mm A 1. Four 16 mm holes drilled in the body about 12 inches mm from the large end with no flange.
As a first step, I would temper this casting to drop the hardness to BHNbefore attempting annealing.
Also, if distortion is a concern, provide some supports. Are you using cubic boron nitride tips or carbide tips for machining?
ASTM A Class I Type A | Ni-Hard 1 High Chrome White Iron
If the issue is that they take longer to machine or they go through tooling faster, can you throw more money at the machine shop to just work through it? Worth a shot for a few parts, for 50 parts that approach isn’t going to be realistic. Hi arunmrao, The shop has replied says they are using cubic boron nitride tooling. So now we are waiting to hear from the foundry about how to get the hardness down to machinable levels. And we should try to confirm the actual material.
If distortion is a possibility and it sounds like it is then re-hardening is going to be mighty risky, so I’d much prefer machining to be the last step.
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