Preheating is a commonly used practice in welding. Welders apply heat after welding or between passes. Let’s understand both preheating and interpass temperature in detail.
What is Preheat Temperature in Welding?
Preheating refers to the process of increasing the temperature of the base or parent material on both sides of the joint. This temperature in welding should be higher than ambient. Basically, preheating is the minimum temperature that the parent material needs before welding.
The preheat temperature for welding is necessary for the following reasons:
-
Decrease shrinkage stresses in the weld and Heat Affected Zone (HAZ).
-
Improve microstructure of HAZ.
-
Slow down the cooling rate to reduce hardness.
-
Remove moisture to avoid hydrogen buildup, porosity and probability of cracking.
-
Reduce distortion that might occur due to thermal stresses.
-
Compensate for high heat loss.
-
Eliminate grease oil and scale for the joints to enable quick welding speeds.
What is the Preheating Temperature of Steel?
It should be 30-50 degrees centigrade above the upper transformation temperature.
What is the Preheating Temperature of Cast Iron?
It should be around 200-310 degrees centigrade.
What is Preheat Temperature for Carbon Steel?
It depends upon various factors like thickness,base mats,Chemistry etc .
However, please note that the preheat temperature may vary across the base metals and primarily depend on the following factors:
-
Chemistry of the base metal
-
Strength of the base metal
-
Thickness of the base metal
-
Use of low-hydrogen process
-
Joint type, thickness and restraint
The welders can consider the following methods to determine preheat temperature:
-
HAZ Hardness Control Method
-
Manufacturer’s Recommendations
-
Hydrogen Control Method
-
Slide Rule Preheat Calculator
-
Table 3.3 in American Welding Society’s D1.1 Structural Welding Code
What is Interpass Temperature in Welding?
Interpass temperature refers to the base material’s temperature before the next pass is laid. It is the temperature at which ensuing weld runs are deposited. It exists between two beads, layers or shifts.
It is indicated in terms of minimum and maximum temperature. The minimum interpass temperature should be at least as high as the maximum one. If specific mechanical weld metal properties are required, then it is important to control the maximum temperature.
There are few reasons to measure interpass temperature:
-
Avoid overheating.
-
Control the microstructural development of weld metal.
-
Ensure the consistency in all welds made in the procedural qualification.
-
Reduce the loss of alloying elements in welds.
-
Improve the notch toughness properties.
-
Prevent deterioration of mechanical properties of weld metal and HAZ.
-
Lower the probability of distortion.
-
Minimize the risk of hydrogen, solidification and liquid cracking.
-
Maintain sufficient wetting of the molten pool onto the base material.
Both preheating and interpass temperatures are crucial variables in welding. They both determine the cooling rate. The welders need to strike a delicate balance between preheating and interpass temperatures to achieve the expected welding quality.
.jpg)
28 March 2025 | Welding
An In-Depth Exploration of Low-Alloy Steel: Your Comprehensive Guide
28 March 2025 | Welding
Six-lane expressway of Mumbai-trans-harbour-link (MTHL) connecting Sewri on Mumbai Island
28 March 2025 | Welding
Nagpur - Bori - Tuljapur Road MSH-3 in Yavatmal District (Maharashtra)
28 March 2025 | Welding
Guidelines to Understand Gas Welding: Applications, Advantages & Disadvantages
28 March 2025 | Welding
3 Tips for Finding the Best Mild Steel Electrode for Your Application
28 March 2025 | Welding
Ways To Prevent Weld Defects When Working With Different Materials
28 March 2025 | Welding
How to Select the Right Welding Filler Wires for Stainless Steel Welding?
28 March 2025 | Welding
Building the Narendra Modi Stadium with Norma V and Autotherme-1 Electrodes
28 March 2025 | Welding
Low Alloy Steel Welding in a (PEB) Pre Engineered Building Structure
.jpg)
.jpg)
.jpg)
28 March 2025 | Welding
Welding Rods: Different Types and Tips for Properly Storing and Handling
.jpg)
28 March 2025 | Welding
Tips for Flawless Welds with Stainless Steel Electrodes: Pros and Cons
28 March 2025 | Welding
Exploring Applications and Benefits of Stainless Steel Welding Electrodes
.jpg)
.jpg)
.jpg)
28 March 2025 | Welding
Welding Basics: Joining Metals with Heat and Pressure - A Beginners Guide
28 March 2025 | Welding
Forehand vs. Backhand Welding Techniques: Choosing the Right Method
.webp)
28 March 2025 | Welding
Welding Innovations to Improve Manufacturing Productivity & Quality.jpg)
28 March 2025 | Welding
Implementation of 96.3 CBM Sarambala medium irrigation scheme at Sawantwadi in Sindhudurg.jpg)
.webp)
.jpg)
28 March 2025 | Welding
What are Nickel Electrodes? Exploring Varieties and Applications with Real-world Examples
28 March 2025 | Welding
Exploring the World of Welding Consumables: Types and Applications
28 March 2025 | Welding
Distinguishing Low-Alloy Steel from High-Alloy Steel: Understanding the Variations
28 March 2025 | Welding
Hard Facing Wire - Understanding the Process and Achieving Optimal Result
28 March 2025 | Welding
Exploring the Advantages of Stainless Steel Electrodes in Welding Applications
28 March 2025 | Welding
Weathering Steel vs. Traditional Steel: A Comparative Analysis of Performance
28 March 2025 | Welding
Choosing the Right Welding Rod: Why 6013 Electrodes Might Be Your Ideal Option
28 March 2025 | Welding
Why 7018 Electrodes Are Preferred for High-Strength Welds in Pipeline Construction
28 March 2025 | Welding
Understanding Weathering Steel: Characteristics, Advantages, and Common Applications
28 March 2025 | Welding
Filler Wire vs. Stainless Steel Filler Wire: Understanding the Key Differences
28 March 2025 | Welding
What are Mild Steel Electrodes? A Detailed Explanation of Different Types with Examples
28 March 2025 | Welding
Exploring the Impact of Filler Material on Welding Quality and Durability
28 March 2025 | Welding
A Comprehensive Guide to Submerged Arc Welding Wire: Benefits, Uses, Best Practices & More
28 March 2025 | Welding
Choosing the Right Cast Iron Electrode for Different Welding Projects
28 March 2025 | Welding
Benefits of Using Nickel Electrodes in Corrosion-Resistant Welding
28 March 2025 | Welding
Top Advantages of Cast Iron Electrodes for Industrial Welding Applications
.png)
28 March 2025 | Welding
Key Benefits and Challenges of Using TIG Welding in Industrial Projects
28 March 2025 | Welding
5 Reasons Why 7018 Electrode is the Gold Standard for Welding Professionals
28 March 2025 | Welding
Top 5 Advantages of Flux Cored Arc Welding for Heavy-Duty Applications.png)
28 March 2025 | Welding
Revitalising Power Plant Efficiency: The Role of LoTherme 470M in Drive Shaft Repairs
28 March 2025 | Welding
Lotherme-601: A Game-Changer for Restoring Shoulder Pins in Heavy Machinery
.webp)
28 March 2025 | Welding
How D&H Sécheron Helped Repair a Rotary Kiln’s Cooler Section with LoTherme 352
