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Rockwell hardness numbers for rods and crankshaft #1373074 01/20/13 11:11 PM 01/20/13 11:11 PM
Joined: Aug 2003 Posts: 43,190 Bend,OR USA C Cab_Burge OP I Win
Cab_Burge OP I Win C Joined: Aug 2003 Posts: 43,190 Bend,OR USA	I'm hoping someone on here will know a good range of rockwell hardness numbers for H and I beam steel rods and the same for a decent forged steel crankshaft If I'm remembering correctly the first batch of Ohio Forged Steel Crankshaft CO. I bought where between 22 and 25C rockwell The crank grinders and machine shop I used at that time in SO CA thought that was to soft, I didn't have those reheat treated I have one of those cranks in my 505 C.I. bracket motor and found out recently there is a heat treating company near by, so I thought I would ask on here first and see about having that crankshaft reheat treated next winter, if it really needs it One other question, what do you guys pay for heat treating a B-RB forged steel stroker crank and for a set of 8 rods? Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)

Re: Rockwell hardness numbers for rods and crankshaft [Re: Cab_Burge] #1373075 01/20/13 11:33 PM 01/20/13 11:33 PM
Joined: Mar 2010 Posts: 69 parma,ohio 6 66littlebigmopar member
66littlebigmopar member 6 Joined: Mar 2010 Posts: 69 parma,ohio	I'm not 100% sure but won't heating treating tweak the crank and rods reqiuring then to get straightened. I know when parts at work get heat treated at work the next set is straightening, though there not automotive parts they are carbon steel parts. I know tooling is about 45-50 rockwell.

Re: Rockwell hardness numbers for rods and crankshaft [Re: 66littlebigmopar] #1373076 01/20/13 11:44 PM 01/20/13 11:44 PM
Joined: Jan 2008 Posts: 4,255 Canada WO23Coronet master
WO23Coronet master Joined: Jan 2008 Posts: 4,255 Canada	That Rockwell range sounds about right for a 4140/4340 steel. I wouldn't mess with the heat treating as previously mentioned, maybe get it nitrided for a surface hardening, but I wouldn't do a full on heat treating at this point

Re: Rockwell hardness numbers for rods and crankshaft [Re: WO23Coronet] #1373077 01/21/13 12:06 AM 01/21/13 12:06 AM
Joined: Oct 2003 Posts: 1,409 Ont. Canada 10.90 Racer super street
10.90 Racer super street Joined: Oct 2003 Posts: 1,409 Ont. Canada	Quote: That Rockwell range sounds about right for a 4140/4340 steel. I wouldn't mess with the heat treating as previously mentioned, maybe get it nitrided for a surface hardening, but I wouldn't do a full on heat treating at this point

Re: Rockwell hardness numbers for rods and crankshaft [Re: Cab_Burge] #1373078 01/21/13 12:10 AM 01/21/13 12:10 AM
Joined: Jun 2003 Posts: 52,972 Romeo MI MR_P_BODY Master
MR_P_BODY Master Joined: Jun 2003 Posts: 52,972 Romeo MI	Quote: I'm hoping someone on here will know a good range of rockwell hardness numbers for H and I beam steel rods and the same for a decent forged steel crankshaft If I'm remembering correctly the first batch of Ohio Forged Steel Crankshaft CO. I bought where between 22 and 25C rockwell The crank grinders and machine shop I used at that time in SO CA thought that was to soft, I didn't have those reheat treated I have one of those cranks in my 505 C.I. bracket motor and found out recently there is a heat treating company near by, so I thought I would ask on here first and see about having that crankshaft reheat treated next winter, if it really needs it One other question, what do you guys pay for heat treating a B-RB forged steel stroker crank and for a set of 8 rods? 22-25 rockwell C is like butter....a file is 62 Rc and I would think good quality steel is 45-50 Rc... you dont want them too hard but no where near 25Rc EDIT Axles range from 57-59 Rc Last edited by MR_P_BODY; 01/21/13 12:14 AM.

Re: Rockwell hardness numbers for rods and crankshaft [Re: MR_P_BODY] #1373079 01/21/13 01:11 AM 01/21/13 01:11 AM
Joined: Nov 2009 Posts: 3,082 St. Paul , Mn. tubtar master
tubtar master Joined: Nov 2009 Posts: 3,082 St. Paul , Mn.	I seem to recall 38 rockwell for the SBC " pink " rods , so that does seem soft. Rather than heating , I'd look at a Cryro treatment. Much less distortion of the part and more consistent grain structure afterwards. I think because the temperature control is tighter with freezing as opposed to heat. Tooling rockwell numbers depend on material and end use , with forming tools typically using lower numbers and different types of steel than stamping or cutting tooling. Powdered metals skew the curve a bit too , but their prices kept us from using a lot if it when I was in that line of work. But crankshafts are not through hardened like most tools......generally a case hardening that is usually less than .030 deep......often much less.

Re: Rockwell hardness numbers for rods and crankshaft [Re: MR_P_BODY] #1373080 01/21/13 02:43 AM 01/21/13 02:43 AM
Joined: Jan 2008 Posts: 4,255 Canada WO23Coronet master
WO23Coronet master Joined: Jan 2008 Posts: 4,255 Canada	Quote: Quote: I'm hoping someone on here will know a good range of rockwell hardness numbers for H and I beam steel rods and the same for a decent forged steel crankshaft If I'm remembering correctly the first batch of Ohio Forged Steel Crankshaft CO. I bought where between 22 and 25C rockwell The crank grinders and machine shop I used at that time in SO CA thought that was to soft, I didn't have those reheat treated I have one of those cranks in my 505 C.I. bracket motor and found out recently there is a heat treating company near by, so I thought I would ask on here first and see about having that crankshaft reheat treated next winter, if it really needs it One other question, what do you guys pay for heat treating a B-RB forged steel stroker crank and for a set of 8 rods? 22-25 rockwell C is like butter....a file is 62 Rc and I would think good quality steel is 45-50 Rc... you dont want them too hard but no where near 25Rc EDIT Axles range from 57-59 Rc Yeah and files snap like twigs when you put any kind of load on them as well, not exactly what u want for a crank. U can take 4140/4340 to the low mid 40's for RC with full heat treating but that's where u want it for making vice jaws, tooling (not cutting tools), and for something thay needs high wear resistance. The higher u go for RC, you lose toughness and maleability, which a crank needs. Go to most any machine shop and ask for a shaft/ bushing whatever to be made and it needs to put up with alot of abuse (loader bucket pins/bushings etc) and they go right to there rack of 4340 and use that in its non heat treated form, which is in the mid 20's for RC. With all the torsional/longditudal forces on a crank I don't think u would want it very hard, although my experience is from the general maching end of it so I could be wrong

Re: Rockwell hardness numbers for rods and crankshaft [Re: WO23Coronet] #1373081 01/21/13 02:53 AM 01/21/13 02:53 AM
Joined: Jun 2003 Posts: 52,972 Romeo MI MR_P_BODY Master
MR_P_BODY Master Joined: Jun 2003 Posts: 52,972 Romeo MI	Yeah and files snap like twigs when you put any kind of load on them as well, not exactly what u want for a crank. U can take 4140/4340 to the low mid 40's for RC with full heat treating but that's where u want it for making vice jaws, tooling (not cutting tools), and for something thay needs high wear resistance. The higher u go for RC, you lose toughness and maleability, which a crank needs. Go to most any machine shop and ask for a shaft/ bushing whatever to be made and it needs to put up with alot of abuse (loader bucket pins/bushings etc) and they go right to there rack of 4340 and use that in its non heat treated form, which is in the mid 20's for RC. With all the torsional/longditudal forces on a crank I don't think u would want it very hard, although my experience is from the general maching end of it so I could be wrong I used the file as a reference point so he could get a idea... thats all... if you want the right numbers its wise to call the manufacturer of the better cranks and rods... on the axles I pulled the prints at work(Chrylser) so I could get the RC range so I could get a set of axles cut and hardened to the upper end of the spec

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