lyuv Posted February 18, 2018 Share Posted February 18, 2018 Hi all, Made a blade from 125sc steel. Quenched in canola oil and tempered (twice) at 200c-220c (390f-430f). The problem - as I sharpen the blade, it chipps. Just from sharpening. It happens with fine whetstones, using an angle guide (10deg). Along all the blade. Note: before the hardening heating (with 5 minuts soak), I made several cycles of heat to orange and cool to black. This was suggested to me to achieve a black finish ("curo uchi"). could this cycling be the reason? I have not fixes handle yet, so I can re-temper, if there is a point. Would like your thoughts on that as well. 125sc is a pure high carbon (1.25%) steel with significant manganese content. The quench media and tempering temperature were suggested by the manufacturer. Thanks, Quote Link to comment Share on other sites More sharing options...
lyuv Posted February 18, 2018 Author Share Posted February 18, 2018 This is what the chipping looks like. The bright (secondary) bevel is about 2mm wide. Quote Link to comment Share on other sites More sharing options...
Steve Sells Posted February 18, 2018 Share Posted February 18, 2018 Never heard of that steel here in the states, What do the spec sheets say about tempering ? Have you read through the knife HT section? I will relocate this post there Quote Link to comment Share on other sites More sharing options...
lyuv Posted February 18, 2018 Author Share Posted February 18, 2018 I got this steel from Wirtz Achim Germany. He is a renowned metalsmith and speciality steel producer (I think he uses other factories to manufacture to his specifications). This is "his" steel, so no standard tempering info, but I did get short reference from him by mail, saying to do as I did (quench in oil. temper temp). I probed the blade's edge under microscope. When applying pressure, it breaks like glass and does not bend. Will tempering at higher temp help? that is, without loosing much of the hardness. Thanks, Quote Link to comment Share on other sites More sharing options...
Steve Sells Posted February 18, 2018 Share Posted February 18, 2018 It is not a surprise with all that extra carbon floating around, that is why I asked about spec sheet, if you followed that and its still too hard then you need to read the posts about how to HT because I already explained it there, and I refuse to retype it all again. Basically re temper at a few degrees higher each time until it works Quote Link to comment Share on other sites More sharing options...
basher Posted February 19, 2018 Share Posted February 19, 2018 Its a strange steel, I made some test blades from it laminated with pure iron cladding (along with some 145C with same treatment) 4 or 5 years ago and could not get the blades to "not chip" using a brass rod test, tempered at 220 and then 250C. so I kept them and have had great use from them. In practice they do not chip at all in a kitchen environment. I would play around with edge geometry (which makes a huge difference to chipping or not) and tempering temperature to see if you can get a result you are happy with. Quote Link to comment Share on other sites More sharing options...
lyuv Posted February 19, 2018 Author Share Posted February 19, 2018 Thanks. First, it's good to know it's not just me or my mistakes. Indeed I found the edge angle makes a great difference. I re-tempered at 250. It's less brittle. enough to have the same 10deg edge, but with much smaller chips and a very sharp edge. Quote Link to comment Share on other sites More sharing options...
Steve Sells Posted February 19, 2018 Share Posted February 19, 2018 sometimes we find out the hard way that not all steel are good for blades, or at least the blade we planned Quote Link to comment Share on other sites More sharing options...
templehound Posted March 7, 2019 Share Posted March 7, 2019 Saw this a bit late. I worked with the steel for a couple of blades and it is called after the books a low alloy because of the Mg content, but it reacts like a "non alloyed" carbon tool steel with over 1% carbon. IMHO the several cycles heated to orange made it coarse grain, which results in chipping. This steel should only be soaked until it has reached its quenching Temperature. Not longer.1% carbon is in solution fast, after that grain growth starts immediately. The Mg is only in to slow down cooling rate which makes it more suitable for oil quenching in 810-820 degrees C It is tempered at least with 210 degrees C, two cycles each 50 min.quench in cold water between cycles to prevent tempering brittleness . dont temper above 230 degrees, gets brittle too. I think the most important feature of this steel is its purity.Sulfur content is like shirogami 1 and Phosphorus even 8 times lower. In fact this steel is to me more sensible than other comparable steels and only little differences in HT, including temperature of quenching oil, blade geometry and grinding temperature can have remarkable and different results on blade performance. It works very easy, it is not very edge holding but from good toughness that allows making bigger blades of it with corresponding adjustments in edge geometry. It also sharpens extremely easy....just pick a flat stone form the river shore (or a marble base at a museum)....thus one can assume that it makes good blades for the field and forest....and of course for the kitchen. Quote Link to comment Share on other sites More sharing options...
lyuv Posted March 7, 2019 Author Share Posted March 7, 2019 13 hours ago, templehound said: IMHO the several cycles heated to orange made it coarse grain, which results in chipping. This steel should only be soaked until it has reached its quenching Temperature. Does that mean this steel is not suitable for forging (as forging takes it to higher temperatures)? Thanks for that wealth of info! Quote Link to comment Share on other sites More sharing options...
Frosty Posted March 7, 2019 Share Posted March 7, 2019 High Alloy does NOT refer to carbon content, it refers to the number and % of alloying metals. There most certainly are low alloy high carbon steels and high alloy low carbon steels. Alloy and Carbon content are two different things. Seriously, steel isn't an alloy at all, carbon isn't a metal and an alloy is a mixture of metals. Confused more than you were before? That's metal for you. Frosty The Lucky. Quote Link to comment Share on other sites More sharing options...
Buzzkill Posted March 7, 2019 Share Posted March 7, 2019 Welllll, technically steel is still an alloy since an alloy can be a homogeneous mixture of 2 or more metals or of a base metal with a non-metal, but at some point we're splitting hairs. If you want to know the impact of certain elements on the properties of steel I found a web page that lists quite a few of them. It appears to be focused mainly on aircraft construction, but it still has good information about steel composition in general. https://quizlet.com/181501504/1-metals-and-metal-alloys-flash-cards/ Quote Link to comment Share on other sites More sharing options...
templehound Posted March 8, 2019 Share Posted March 8, 2019 19 hours ago, lyuv said: Does that mean this steel is not suitable for forging (as forging takes it to higher temperatures)? Thanks for that wealth of info! As far as I know all carbon and-low alloy tool steels can be forged...and of course forging takes them to higher temperatures . all those steels have their own hot working temperature.....and some of them crack faster when forged too cold and some of them burn red brittle, or bright right away when forged too hot, and some of them both. afterwards you have to make up for everything of normal, negative side effects that naturally happen during the forging process in the final HT. Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted March 8, 2019 Share Posted March 8, 2019 It is possible to have a steel that is both cold short and hot short making it extremely difficult to forge; but I believe that if you can hit that narrow temperature window if can be forged. (Traditionally steels had issues with sulfur and phosphorus causing hot/cold shortness which is why values for these elements are usually in alloy specifications under the "less than" categories.) Quote Link to comment Share on other sites More sharing options...
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