力和敏感材料 • Solutions解决方法 – Control hydrogen 控制氢含量
Hydrogen氢
Stress应力
Sensitive Material
敏感材料
Underbead Cracking 焊道下裂纹
• Cause : 原因
Excessive hydrogen and stress and a sensitive base material (HAZ)太高的氢含量，应力和敏感材料
• Solutions解决方法
– Use proper joint detail使用正确的接头 – Control penetration (current density)控制 熔深（电流密度）
Surface Profile Cracking 表面成形裂纹 • Cause 3: – Concave surface cracks during solidification内凹的焊道表面在凝固 时开裂
Hydrogen氢
Stress应力
Sensitive Material
敏感材料
Underbead Cracking 焊道下裂纹
• Cause : 原因
Excessive hydrogen and stress and a sensitive base material (HAZ)太高的氢含量，应
No Cracking
40
30
Mn/S > 20:1
Cracking
20
10
0.06
0.08
0.10
0.12
0.14
0.16
0.18
Carbon, wt %
Segregation Cracking 偏析裂纹 • Cause 1: 原因
low melting point constituents segregate to the centerline during solidification在凝固
1/4”
FCAW-g
1/4”
FCAW-g
Segregation Cracking 偏析裂纹
Solutions:解决方法 • Minimize alloy pickup减少合金拾取
– Minimize admixture减少熔和比 – Minimize penetration (minimize current density {d= I/A})减少熔深（减少电流密度） – May require joint detail change或许需要改 变坡口形式
Segregation Cracking 偏析裂纹
Solutions:解决方法 • Minimize alloy pickup减少合金拾取
– Minimize admixture 减少熔和比 – Minimize penetration (minimize current density {d= I/A}) 减少熔深（减少电流密度）
Transverse Crack横向裂纹
Throat Crack焊喉处裂纹
Toe Crack 焊趾裂纹
Crater Cracks in Aluminum Weld铝焊接中的弧坑裂纹
Underbead Cracks焊道 下裂纹
Centerline Cracking 焊缝中心裂纹
Underbead Cracking焊道下裂纹
AWS D1.1 Figure 3.2
Groove Preparation
Root OpБайду номын сангаасning R = 1/4
R = 3/8 R = 1/2
Groove Angle
a = 45o a = 30o a = 20o
Proper root geometry正确的打底焊道
a
R
Improper root geometry:不正确的焊道
Buttering Layer预堆边
Segregation Cracking 偏析裂纹
Solutions:解决方法 • For steels with high sulfur, increase the manganese content of the electrode.对于含 高硫的母材，增加焊丝的锰含量
UCS = 230C + 190S + 75P + 45Nb – 12.3 Si - 5.4 Mn – 1
Cracking Contributors裂纹支持元素
TWI Hot Cracking Susceptibility:
UCS = 230C + 190S + 75P + 45Nb – 12.3 Si - 5.4 Mn – 1
Segregation Cracking 偏析裂纹 Solutions:解决方法 • Minimize alloy pickup减少合金拾取
– Minimize admixture减少融合比 – Minimize penetration (minimize current density {d= I/A})减少熔深（减少电流密度） – May require joint detail change或许需要改变坡 口形式 – Use of “buttering” techniques 采用“预堆边”
a
R
a is small, but R is increased.夹角小 了，但间隙增加了
“Popsicle” Cracking 凝固裂纹 • Cause 2: 原因
Improper width-to-depth ratio leads to solidification problems不正确的宽深比
Improper width-to-depth ratio leads to solidification problems不当的焊缝宽深比
• Solutions解决方法
– Use proper joint detail使用正确的接头
1.4
W/D > 1.2 1.0
D
W
AWS D1.1 Figure 3.2
– Low in low melting point constituents减少 低熔点的元素
TWI Hot Cracking Susceptibility: TWI热裂纹敏感指数
UCS = 230C + 190S + 75P + 45Nb – 12.3 Si - 5.4 Mn – 1
UCS < 10 “High Resistance to Cracking不易开裂”
a
R = too small太小
Proper root geometry正确的焊道
a
R= small, but a is increased 小 但夹角增加了
Improper root geometry:不正确的焊道
a
R
R and a are both too small 夹角和间 隙都太小
Proper root geometry正确的焊道
Surface Profile Cracking表面成形裂纹
Surface Profile Cracking 表面成形裂纹
Surface Profile Cracking 表面成形裂纹
• Cause 3: – Concave surface cracks during solidification内凹表面在凝固时开裂 • Solution:解决方法 – Make convex surfaces焊成凸的焊缝
Transverse Cracking横向裂纹
Centerline Cracking焊道中心裂纹
Centerline Cracking 焊道中心裂纹
(even though not in center of joint)即使不在中间
Centerline Cracking 焊道中心裂纹
Cause 1: Segregation Cracking 原因1：偏析裂纹 • Low melting point constituents segregate to the centerline during solidification在凝固时低 熔点的元素聚集到中间
Cracking Resistors
裂纹阻止元素
Segregation Cracking 偏析裂纹
Solutions:解决方法 • Use “good” steel使用 “好”的钢 材
– Low in low melting point constituents减少 低熔点的元素 – Avoid “free machining” steels for welded applications 避免使用“不需机加工”的钢材
Why Do Welds Crack?
焊缝为什么会开裂？
David Wang
王秀伟
When did the crack occur?
何时出现裂纹？
During fabrication?
生产中？
In service?
运行中？
Where is the crack?
裂纹出现在哪里？
Longitudinal Crack纵向裂纹
“HOT CRACKING热裂纹 ”
Underbead Cracking焊道下裂 纹
Transverse Cracking横向裂纹
“COLD CRACKING冷裂纹 ”
Underbead Cracking焊道下裂纹
Underbead Cracking 焊道下裂纹 • Cause : 原因
Excessive hydrogen and stress and a sensitive base material (HAZ)太高的氢含量， 应力和敏感材料