失效及缺陷组织照片

leomet

Continue.....................

leomet

2000鋁合金起落架零件, 起飛前例行檢查時發現裂紋.

leomet

kaiyun100 发表于 2010-8-5 10:58
leomet ：您好
感谢您的上传和说明，收益很大。
想请教一下：1.渗碳后表面微脱碳为什么易淬裂？2 渗碳后 ...

A very late reply.

http://www.rclbbs.com/forum.php? ... &extra=page%3D1

Please see #7.

不同的C%, 不同的M變態膨脹量.

leomet

leomet 发表于 2015-1-18 16:48
2000鋁合金起落架零件, 起飛前例行檢查時發現裂紋.

Thermal Fatigue Cracking

leeyoung007

leomet 发表于 2014-12-20 14:49
Continues...............

Dear Leomet, the distance among the indentations is too close to comply with the ISO standard.

leomet

業餘失效分析師的專業照片

USB 顯微鏡攝 + 手電筒 打光

ESR H13  P/M compaction punch

Crack found after 8K strokes.

leomet

Same as above posting. but sample is placed

On a red leave, under the sun.

leomet

汽機車零件最頭痛的問題就是製造過程如果經過酸洗, 一定會有氫原子躦入鋼的結晶結構裡, 這些氫原子後來會聚集到晶界結合成分子, 形成往外撐的氣体壓力. 加上外力後, 常常就沿著晶界破裂. 我們稱之為氫引起的脆性破裂 Hydrogen induced cracking .

下圖完全是沿晶界的脆性破裂, 主要是去氫處理未做好. 晶界間有縫隙 是H裂的特徵.

leomet

青子衿 发表于 2014-11-12 14:23
请教下您，图片中红色区域是什么组织，为什么与一般的调质金相不同，是如何造成的？

A late reply: You should know I do not answer questions.

This area is solute-poor and has a poorer hardenability. So, on air cooling, that area transformed to "upper products", like F, P.

Also, this is no 調質 process at all.

leomet

鋼材: SCM 440.  過熱使晶粒粗大 與 水壓太大致使冷卻過度, 導致淬裂.

油孔銳角 over heating + over cooling ---> quench crack

over heating + over cooling ---> This is the formula for quench crack.

leomet

2008 輔導案例

粗晶+微縮孔 導致短命

leomet

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leomet

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leomet

浸蝕不均, 導致誤判. 建議使用浸浴式腐蝕(immersion eching). 腐蝕不要用滴的或刷的. 滴上幾滴浸蝕液再用棉花棒刷開, 常會有此不均勻的現象. 訓練/經驗不足時 就會誤判. 以下就是檢驗者的判讀:

在ZD0642我們看到"碳累積在一個永久變形區域"***(容易導致裂痕). 但這是在材料內部非表面,此批仍可允收.

***這句話是啥?外行的可真會被這種專業術語給唬倒. What on earth is this ! 這是啥東東啊! Das ist nicht richtig.

Yellow arrows:黃箭頭所指黑線是front-line or border-line of etchant drops on the spcimen. After swabbing, you get a black line like this. This  line is   severely over-etched , so it shows black. Red arrows: undissolved or retained carbide; aqua arrows: carbide particles  precipitated during tempering. The more "sub-microscopic" carbide particles dispersion, the more ductile will the ballpin be. Ductile (Dimpled) fracture surface is resulted from the presence of these super-tiny carbide particles.

這個台灣公司, 聘了一個半調子的德國金相工程師, 有時會給出這樣的檢驗報告. 上段英文是寫給他看的. 誰說遠來的和尚較會唸經.

AISI 4140 Ballpin 金相.

leomet

JIS SNCM 440; AISI 4340, as-quenched,  HRC ~51,  ~92%Martensite.
The rest is non-Martensitic product. Note: as-quenched condition gives
better contrast between M and non-M, especially B.

leomet

Raw material of 4340.

leomet

1010 steel pipe, drawn, then induction hardened.

Photos show different positions along the pipe thickness.

leomet

4340, polished surface, as-quenched in vacuum furnace, 1020C
Photos show surface relief from phase transformation.

leomet

S45C nomalized . Ferrite + Pearlite

leomet

Induction overheated QT iron.

為教學所做的過熱QT試片.