焊接裂纹产生及预防
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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
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
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
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
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
时低熔点的元素聚集到中间 • Solutions解决方法
– Use “good” steel使用“好”的母材 – Minimize alloy pickup减少合金的拾取 – For high sulfur, use higher Mn electrodes 对于高硫母材，采用高锰焊丝
“Popsicle” Cracking 凝固裂纹 • Cause 2: 原因
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
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）
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
UCS > 30 “Strong Susceptibility to Cracking非常容易开裂”
Based on WELD METAL Composition基于母材的成分
Linnert 4th Edition, Volume 1
TWI Hot Cracking Susceptibility:
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
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
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
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”
• Solutions解决方法 – Control hydrogen控制氢含量
• • • • Selection of filler metals焊材的选择 Storage and exposure of filler metals存储和使用 Control of base metal cleanliness母材的清洁 Maximize diffusion of hydrogen加快氢的扩散
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
Low Melting Point Ingredients 低熔点的元素
•Carbon (C)碳 •Lead (Pb)铅 •Zinc (Sn)锌 •Copper (Cu)铜 •Phosphorous (P)磷 •Sulfur (S)硫
Segregation Cracking 偏析裂纹
Solutions:解决的方法 • Use “good” steel使用 “好”的钢 材
• 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
• Lower currents小电流 • Lower voltages低电压 • Shielding gas changes改变气体 • If vertical, change to vertical up 立焊时采 用向上焊
Centerline Cracking 焊道中心裂纹 Cause 1: Segregation Cracking 偏析 Cause 2: “Popsicle Cracking”凝固 Cause 3: Surface Profile 表面成形
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
AWS D1.1 Figure 3.2
Groove Preparation
Root Opening 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
Ratio of manganese to sulfur
60 50
40
No Cracking
30
Mn/S > 20:1
Cracking
20
10
0.06
0.08
0.10
Байду номын сангаас
0.12
0.14
0.16
0.18
Carbon, wt %
Ratio of manganese to sulfur
60 50
Mn/S > 850(%C) - 83
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
– 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”
Improper width-to-depth ratio leads to solidification problems不当的焊缝宽深比
LIQUID
SOLIDIFIED
Width (W)
Depth (D)
CRACK
LIQUID
SOLIDIFIED
CRACK
“Popsicle” Cracking 凝固裂纹 • Cause 2:原因
“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
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
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
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
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
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
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
时低熔点的元素聚集到中间 • Solutions解决方法
– Use “good” steel使用“好”的母材 – Minimize alloy pickup减少合金的拾取 – For high sulfur, use higher Mn electrodes 对于高硫母材，采用高锰焊丝
“Popsicle” Cracking 凝固裂纹 • Cause 2: 原因
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
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）
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
UCS > 30 “Strong Susceptibility to Cracking非常容易开裂”
Based on WELD METAL Composition基于母材的成分
Linnert 4th Edition, Volume 1
TWI Hot Cracking Susceptibility:
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
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
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
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”
• Solutions解决方法 – Control hydrogen控制氢含量
• • • • Selection of filler metals焊材的选择 Storage and exposure of filler metals存储和使用 Control of base metal cleanliness母材的清洁 Maximize diffusion of hydrogen加快氢的扩散
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
Low Melting Point Ingredients 低熔点的元素
•Carbon (C)碳 •Lead (Pb)铅 •Zinc (Sn)锌 •Copper (Cu)铜 •Phosphorous (P)磷 •Sulfur (S)硫
Segregation Cracking 偏析裂纹
Solutions:解决的方法 • Use “good” steel使用 “好”的钢 材
• 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
• Lower currents小电流 • Lower voltages低电压 • Shielding gas changes改变气体 • If vertical, change to vertical up 立焊时采 用向上焊
Centerline Cracking 焊道中心裂纹 Cause 1: Segregation Cracking 偏析 Cause 2: “Popsicle Cracking”凝固 Cause 3: Surface Profile 表面成形
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
AWS D1.1 Figure 3.2
Groove Preparation
Root Opening 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
Ratio of manganese to sulfur
60 50
40
No Cracking
30
Mn/S > 20:1
Cracking
20
10
0.06
0.08
0.10
Байду номын сангаас
0.12
0.14
0.16
0.18
Carbon, wt %
Ratio of manganese to sulfur
60 50
Mn/S > 850(%C) - 83
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
– 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”
Improper width-to-depth ratio leads to solidification problems不当的焊缝宽深比
LIQUID
SOLIDIFIED
Width (W)
Depth (D)
CRACK
LIQUID
SOLIDIFIED
CRACK
“Popsicle” Cracking 凝固裂纹 • Cause 2:原因
“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
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