失效及缺陷组织照片

leomet · 发表于 2010-10-16 12:50:54

本帖最后由 leomet 于 2010-10-18 08:42 编辑

回复 257# leomet

高錳鋼枝晶界碳化物, 隔離了基地金屬原子間的結合, 使強度/韌性極度劣化.
需高溫將其固溶入基地後淬水. 此物就不再出現 (冷卻太慢還會出現, 故需淬水).
高錳鋼基地很單純, 故碳化物很容易辨識 (257樓)
如果是淬回火後的模具鋼, 基地看起來"很花"(雜乱), 不小心浸蝕不易被看到...(照片161~ 176)
照片 Bad K 是 SCM440淬回火後金相, 基地更花, 更不易辨識.
看完此篇文章, 希望你辨識枝晶界碳化物功力升一級.

leomet · 发表于 2010-10-21 09:27:55

本帖最后由 leomet 于 2011-2-7 06:55 编辑

Hadfield manganese steel.
As-cast. Showing interdendritic carbides.
They are very detrimental to toughness of any steel
and have to be gotten rid of by "solution annealing".

leomet · 发表于 2010-10-21 09:31:27

本帖最后由 leomet 于 2011-2-7 06:56 编辑

回复 263# leomet

The above specimen, after solution annealing(1020C x 50 min, water-quenched),
intergranular carbides are gone and nowhere to be found. Toughness is
therefore greatly improved and it is ready for its impact service.

leomet · 发表于 2010-10-28 05:44:24

本帖最后由 leomet 于 2010-11-24 03:55 编辑

The edge of a QT casting after machining. Its interior is shown next. (#265)
No spheroidization of graphite at the edge of this casting
because the Mg% in the edge was consumed by the S%
from the surface of furan molds.

leomet · 发表于 2010-10-28 05:47:29

本帖最后由 leomet 于 2012-7-8 12:55 编辑

Steadite islands in a QT iron. It is charicterized by "pepper marks"

Silicon steel sheet contains P element and will produce hard and spiky Steadite
which is very detrimental to the toughness of ductile iron.
So, never ever use scrap silicon steel sheet in the production of ductile iron.
It took tolls on many a foundry . What about you?

Also, this was supposed to be a QT 500. But the percentage of Pearlite
in the matrix is anything but sufficient for QT 500. Therefore it failed an incoming test.

leomet · 发表于 2010-11-2 20:30:10

本帖最后由 leomet 于 2010-11-3 05:52 编辑

photo ~455 (above) and ~980 (below, the last photo).
Steadite has " pepper marks" in it while carbide does not.

leomet · 发表于 2010-11-2 20:35:37

本帖最后由 leomet 于 2010-11-2 22:08 编辑

For your visual delight.

A QT with poor spheroidization treatment.
Steadite has " pepper marks" in it while carbide does not.

leomet · 发表于 2010-11-3 06:41:17

本帖最后由 leomet 于 2010-11-13 07:08 编辑

A Cr25% alloy cast iron part for shop peening machine.
The part wore-out prematurely because of the excessive % of R.A.
in the matrix (white). M : black short needles.
There are a couple of possibilities leading to this fault.
Since you are "the selected few", they are left to you to ponder.
I am not telling here.

leomet · 发表于 2010-11-6 18:28:54

本帖最后由 leomet 于 2010-11-7 06:28 编辑

磷共晶

今11-6 照的. 一客戶從外地(60分鐘車程)拿鑄件來求教. 齒輪箱厚10 mm. HB230
機加工者抱怨刀塊耗損很快.

磷共晶數量太多是主因.

leomet · 发表于 2010-11-27 13:47:49

QT, poorly nodulorized.

leomet · 发表于 2010-11-30 00:37:09

本帖最后由 leomet 于 2011-5-1 07:48 编辑

I earn my daily bread and butter from a score of iron foundries and
consult for a couple of iron foundries and a top P/M tooling fabricator (Edeex, No. 1 in Taiwan) as a moonlighting job.
Hope you guys learn something from reading my posts.
No discussion with me because I am a man of few words, but a man with thousands of photos
which I don't mind sharing with you guys. The best of my collection are posted in this forum, and this forum only.

leomet · 发表于 2010-12-6 14:35:11

A QT casting aimming to get into spec. of QT 500.
Poured at 1300 C. 120mm thick.
Too much (0.50%) Cr was added, resulting in too much
Pearlite and intergranular carbide particles.

leomet · 发表于 2010-12-10 06:27:00

本帖最后由 leomet 于 2010-12-10 06:37 编辑

SCM 440 O.D. > 300 mm 油壓缸
吳老師以前當鋼材行顧問時教裡面的業務人員說: 淬火後沿軸向(軋延方向)筆直的微裂, 通常是材料(偏析嚴重)的問題.
不要再跟客戶強辯說是熱處理的錯. 你接受吳老師的說法嗎?

leomet · 发表于 2011-1-15 11:26:14

淬回火+ Grinding 後發現裂紋.
鍛塊中心是材料缺陷(偏析碳化物, 夾雜物)最多的地方.

leomet · 发表于 2011-1-31 19:16:43

本帖最后由 leomet 于 2011-3-19 18:52 编辑

MA islands ? Austenite islands ?

leomet · 发表于 2011-2-1 21:54:30

本帖最后由 leomet 于 2011-2-5 22:18 编辑

Faulty Q/T H13: too much segregation.
dark area: solute-rich area. You can see some
carbide particles are tinted purple. See upper-left corner of
photo ~437.

shenfuhai · 发表于 2011-2-5 19:58:15

回复 288# leomet

吴老师好,春节快乐!
请问你上楼的H13组织,为什么晶界特别明显,是特意腐蚀的还是热处理组织不良造成的?

leomet · 发表于 2011-2-5 22:16:12

本帖最后由 leomet 于 2011-2-7 06:53 编辑

回复 289# shenfuhai

是特意腐蚀的, using saturated aqueous solution of picric acid.

leomet · 发表于 2011-2-7 07:18:15

It is my sincere hope that all of you guys are now

A year older and a year wiser.

mice00 · 发表于 2011-3-16 14:44:12

回复 262# leomet

solution annealing you know =annealing  （but annealing often  furnace cooling）
but you say：
“Intergranular carbides in Hadfield manganese steel.
They are very detrimental to toughness/strength of any steels.
A solution heating + water quenching will get rid of these carbides
and restore toughness of the steel.”
”高錳鋼枝晶界碳化物, 隔離了基地金屬原子間的結合, 使強度/韌性極度劣化.
需高溫將其固溶入基地後淬水. 此物就不再出現 (冷卻太慢還會出現, 故需淬水).
高錳鋼基地很單純, 故碳化物很容易辨識 (257樓)
如果是淬回火後的模具鋼, 基地看起來"很花"(雜乱), 不小心浸蝕不易被看到...(照片161~ 176)
照片 Bad K 是 SCM440淬回火後金相, 基地更花, 更不易辨識.
看完此篇文章, 希望你辨識枝晶界碳化物功力升一級.“
  only solution annealing （ =annealing） get rid of Intergranular carbides ？

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[原创] 失效及缺陷组织照片

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c

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感應淬火後發現裂紋

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