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对模具热处理比较陌生
疲勞破裂 照片分享
本帖最后由 leomet 于 2017-4-12 10:07 编辑leomet 发表于 2012-6-10 18:50 static/image/common/back.gif
Multi-origin fatigue fracture surface.
Crack originated from broaching marks at a fillet.
Sharing Fatigue Fracture surface photos
起裂點為被尖銳物撞擊後留下的一處凹坑 (< 0.10mm).
M2: 疲勞破裂的海灘紋(beach marks)or貝殼紋.
M2: ab 與cd兩裂面原本有一落差bc, 兩裂面往下發展逐漸合併成同一裂面.
M2: bc 線 中間的小凹點下面首先發展出一小小起裂面(M2 照片, bc連線下的小裂面), 此起裂面與主應力方向幾乎平行, 不利裂面發展. 所以起裂面前進中, 很快就調整/轉向主應力方向, 形成主裂面, 如照片中的小箭頭所示.
M7:黃色小箭頭方向為疲勞主裂面發展方向.
本帖最后由 leomet 于 2012-12-16 23:27 编辑
Microstructures of the failed parts above. brittle fracture surface shown at
related post: #64 in
http://www.rclbbs.com/forum.php?mod=viewthread&tid=69216&extra=page%3D2&page=4
Parts destined to be short-lived if microstructure of fine Pearlite, rather than Tempered Martensite, obtained after Q/T (調質).
Poor Q/T practice found on finished parts, and they did not dare to deliver. The number of parts thus scrapped is 20 thousands. The loss cost my customer "an arm and a leg"--- 2 million RMB, I was told. This loss could have been avoided if their engineers had better knowledge in the heat treatment of steel.
這是汽車變速箱內的單向傳動環, see photo ring 1 & 3. 本帖最后由 leomet 于 2012-8-2 11:44 编辑
fracture surface of a H13 stress ring failed during shrinkage fit. Non-metallic inclusions are very often the culprits that cause parts to fail prematurely. 本帖最后由 leomet 于 2012-11-1 22:16 编辑
leomet 发表于 2012-10-3 22:27 static/image/common/back.gif
Non-metallic inclusions are very often the culprits that cause parts to fail prematurely.
朋友的BobCat鏟車, 機油pump鎖固螺栓斷裂,沒潤滑油供應, 立即導致引擎失效.
給美國原廠的報告.是希望他們負起引擎修理費用的責任. 您好！leomet
我这个铸钢的大约为30CrMnSiNi2Mo材质的试样，工艺为正火+淬火+回火处理，我觉得晶粒太粗大了，您看看是否正常。 leomet 发表于 2008-3-7 21:21 static/image/common/back.gif
P/M 高速钢 金相
P/M = PowderMetallurgy
前三张照片描述的高速钢组织无过热迹象、基体组织为均匀的回火马氏体组织，残余奥氏体几乎绝迹，更可贵的是碳化物的形态、大小及分布状态——颗粒细小、分布均匀、形状圆润——应该是全部经奥氏体化+淬火+充分回火弥散析出所得，几乎看不到原始的共晶碳化物痕迹。表明不仅热处理工艺到位，且之前的锻造比也达到充分的程度才行！好钢！！！
最后一张照片，应是沿钢材纵向切取得金相面，带状碳化物分布明显，尚有改善的空间。
jackson 发表于 2012-5-28 17:09 static/image/common/back.gif
吴老师,
你觉得我上图中的残奥有多少? 1000倍
如此询问吴老师，不妥。
碳化物分布尚可，主要是残余奥氏体未充分转变及回火不充分。
因倍数及上传照片原因，具体奥氏体数量判断较困难。
最好是直接在显微镜下观察金相，可有效回答你的提问。 本帖最后由 leomet 于 2012-12-16 23:33 编辑
Fracture surface of a broken tooling.
Requested by my customer, the root cause of the fracture is a hush-hush. leomet 发表于 2008-3-22 20:00 static/image/common/back.gif
Failed Elbow forming toolingDIN1.2379
也是素材 1.共晶 與 2.晶界 碳化物惹的禍.
非常受益，感谢上传，请上传一些碳钢的低倍缺陷图片。 这么多金相资料，晚辈长眼界了，感谢！ 前辈有做过PM的金相组织吗，希望能上传分析两张，不甚感激 xujie1357 发表于 2013-2-26 00:01 static/image/common/back.gif
前辈有做过PM的金相组织吗，希望能上传分析两张，不甚感激
前面有P/M 氮化與蒸氣處理件.請自己找. 本帖最后由 leomet 于 2014-12-20 14:28 编辑
Ballstud (or ballpin) that failed a fatigue test.
leomet 发表于 2013-3-5 22:26 static/image/common/back.gif
Ballstud tha failed a fatigue test.
短命 熱鍛模
culprit of the fracture: grain boundary carbide from raw material. leomet 发表于 2013-3-5 22:37 static/image/common/back.gif
短命 熱鍛模
culprit of the fracture: grain boundary carbide from raw material.
短命 熱鍛模
晶界碳化物 暗視場 leomet 发表于 2008-3-22 21:11 static/image/common/back.gif
Austempered Ductile Iron: G=GraphiteB = Bainite
Gamma = 过飽和奧氏体 此相柔韌 遇外力相變為Mart ...
碳化物确实不能沿晶分布，会大大降低模具的使用寿命 本帖最后由 leomet 于 2013-5-18 06:15 编辑
way004 发表于 2013-4-9 15:04 static/image/common/back.gif
碳化物确实不能沿晶分布，会大大降低模具的使用寿命
Grain boundary Carbides in H13 hot work steel. They are toughness killer, as we all know.
Photo reposted from the web. leomet 发表于 2013-4-9 22:26 static/image/common/back.gif
Grain boundary Carbides in H13 hot work steel.
Photo reposted from the web.
Dear Master! what are the lines inside the grain about the picture x2.jpg ? Are they the sub-boundaries ?
Many thanks!