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焊接工程
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engines
电弧焊热输入与热影响区
Arc-welding heat input & HAZ
HI=η·V·I/(v·1000)=0.933kJ/mm · HI∝I ∝1/v · HAZ宽
HI = η·V·I /(v·1000) kJ/mm · η=0.8 (GMAW) · V=28 V
碳当量(IIW)与钢的可焊性
Carbon equivalent (IIW) & weldability
CE=C+Mn/6+(Cr+Mo+V)/5+(Ni+Cu)/15=0.457 · <0.40易焊/>0.60高危
CE = C + Mn/6 +(Cr+Mo+V)/5 +(Ni+Cu)/15
防氢致冷裂的焊前预热温度
Preheat temperature to avoid hydrogen cold cracking
Tpreheat=350√(CE_total−0.25)=173°C · 随CE/板厚升 · 防冷裂
CEt = CE + 0.005·t·CE · Tpreheat = 350·√(CEt − 0.25) °C
焊接 t8/5 冷却时间
Weld cooling time t8/5
t8/5 800→500°C · 决定HAZ组织硬度 · HI大则t8/5长
Time to cool from 800 °C to 500 °C — it governs the HAZ microstructure, hardness and toughness
焊缝稀释率与合金成分
Weld dilution & resulting composition
稀释率=熔化母材/总熔池 · 影响焊缝成分 · 堆焊/异种钢
The fraction of the weld that is melted base metal — it pulls the weld composition toward the base metal
角焊缝有效喉厚与承载力
Fillet weld throat & shear capacity
喉厚a=0.707·焊脚 · 承载a·L·τ · 等腰直角三角
For an equal-leg fillet the design throat a = 0.707·z; capacity = throat × length × allowable stress
焊接符号标注(AWS/ISO)
Welding symbol notation (AWS/ISO)
AWS/ISO符号 · 角焊/坡口 · 箭侧/另一侧 · 尺寸长度
Reference line + arrow + weld symbol: below the line = arrow side, above = other side, tail carries the process
焊接接头系数与壳体壁厚(ASME VIII)
Weld joint efficiency & shell thickness (ASME VIII)
t=PR/(SE−0.6P) · E射线等级:全检1.0/局部0.85/不检0.70
A lower joint efficiency E means a thicker pressure shell: t = P·R /(S·E − 0.6·P)
焊机负载持续率(暂载率)
Welding power-source duty cycle
负载持续率=起弧/10min% · 降额I₂=I₁√(D₁/D₂) · 过热
The higher the duty cycle, the lower the allowable current: I₂ = I₁·√(D₁/D₂)
焊接变形与收缩
Welding distortion & shrinkage
横向/角变形/纵向收缩随热输入 · 对称焊/反变形
Non-uniform heating & cooling → transverse · longitudinal · angular distortion
电弧热效率与热输入
Arc efficiency & heat input
η:SAW0.95>GMAW0.8>SMAW0.75>GTAW0.6 · 影响热输入熔敷
η = fraction of arc energy reaching the work · HI = η·V·I/(v·1000)
焊接熔敷率
Weld deposition rate
熔敷率kg/h=送丝×截面×ρ×效率 · 决定生产率
DR = WFS · (π·d²/4) · ρ · η (kg/h)