Forging problem

C

cwhittington

Joined
Sep 6, 2002
Messages
106
I've had a few pieces of steel crack on me lately when they are at an orange heat and I can't figure it out- 2 of them were old leaf springs and could have been cracked already, but one was a new R.R. spring clip, and I didn't know soft/hot steel would crack like that. I also had a piece of
grade 60 rebar do the same thing. What might have caused it?
Thanks in advance-
 
there could be sveral reasons, what kind of cracks were they? clean or spiderweb?
The two springs could have had cracks, which is why it is usually better to start with new steel.
Rebar is known for having impurities and inclusions in it, I am not sure about how clean the grade 60 is, but standard rebar is a gamble
I am not sure what hapened with the rr clip, did it have any sharp cut outs, a right angle can develop a lot of stress, and a crack could form off of it. If it was more of a spiderweb pattern crack, it could be that the clip is made from an alloy that is red-short. some alloys have temperature ranges where forging can cause the steel to crack, or crumble. It may appear like cottage cheese, especially if it has been overheated and the grain has grown considerably

hope this helps,
Ken
 
Ken- thanks for the reply- I will have to look at the spring clip tonight- there was a cut out but I don't think it had any right or sharp angles except at the edges- I think I will bevel the edges first from now on. I think you might have the answer with the hot short because I had been hammering on it maybe 5 seconds when several cracks appeared suddenly after a single blow. Does 5160 hot short like that or would it just have been old cracks or inclusions in the leaf springs? I know the risk I take with scrap, but I want to develop my skills before using the more expensive stuff- and I love scrounging anyway!
Thanks again
 
grinding the edges a bit should help, I have had very good results with 5160, and it hasen't red-shorted on me, though some steels with more chrome can.
If you want to keep scrounging, I might suggest coil springs, as they seem to develop fewer stress cracks in use than leaf springs. Old files work well, but get solid steel ones, not case hardened (often cheap files and imports from india, china, and pakistan). aneel them, grind the teeth down, and then start forging. They are usually 1095, w1, or w2, all very forgiving steels for a beginner.
Lawn mower blades also work well, I have found that many are made with a low nickel, low silicon steel with about .8%carbon, it forges relatively well, and heat treats easily in oil.
Also note, some leaf springs are being made of 6150, a low chrome steel with a bit of vanadium, it forges a little harder than 5160, but is very tough, and suited to choppers.
Well, goiod luck,
Ken
 
I was having the same problem with new 5160 when I was forging.

Even though the steel was orange, the cracks were happening. The steel was cooling off but I still had to give it one last hit.

When I took my time and only gave the steel a couple of hits then put the steel back while it was still glowing red I didn't have any cracks.
 
First,,,,what is a " R.R. spring clip"?


2nd....I have had a few cracks with 5160 too...not sure why for sure,,,,once it happend when I was hitting the steel a bit too much as it cooled,,,could well have cracked because of that.

One time I had some 5160 steel crack for no reason I can think of,,,I was just forging the steel load shaft down flat like normal,,,things were going good,,,,I was not over-heating nor under-heating,,,yet all of the sudden I saw a crack?


At the time I blamed myself,,,but I was never really sure what happend,,,,,I asked a well known knife maker and he spoke of strain that builds up when one part of the blade is worked hard in the forge right next to other parts that are not....
 
DaQo'tah- I was refering to a railroad spring-clip. They are used to secure the track in places subject to a lot of movement. I think that I must have overworked the steel and or allowed it to cool too much- I was really going nuts with the hammer. Thanks all for the responses!
 
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