📋 Case Study

Tractor Frame Crack Repair at Tier-1 OEM Service Center

Crack located near rear axle mount under cyclic torsional load; customer warranty claim pending

🏗️ Project Overview

Repair of fatigue-induced longitudinal crack in John Deere 8R Series chassis frame

🎯 Challenge

Crack located near rear axle mount under cyclic torsional load; customer warranty claim pending

🔧 Design Approach

Two-pass SMAW repair with preheat (150°C), controlled interpass (<230°C), and post-weld UT + hardness mapping; WPS qualified per AWS D1.1 Annex K for in-service repairs

📐 Design Diagram

AI-generated project design illustration

📐 Key Calculations

Preheat Temperature

100 + (1/4 × Carbon Equivalent × 1000)

Result: 152°C

Ensures HAZ toughness >35 J @ -20°C

Hardness Limit

350 HV max in HAZ per AWS D1.1 Table 4.1

Result: 342 HV

Prevents brittle fracture initiation

📊 Results

Zero re-crack after 1,200 hrs field operation; passed OEM audit; reduced downtime by 62% vs. replacement

💡 Lessons Learned

• •Preheat must be verified at three points across joint width
• •Hardness testing requires 3-point traverse across HAZ

✅ Key Takeaways

• 1Preheat must be verified at three points across joint width
• 2Hardness testing requires 3-point traverse across HAZ