You may minimize heat input by using small diameter weld rods. Weld a little, skip forward with no weld, then weld a little more. If you forcibly tac them, you prohibit movement, which will eventually lead to serious warp or fracture.
Chiller bars may be used to dissipate heat. Placed adjacent to the weld, they act to absorb some of the heat heat sink and slow the rate of cooling.
Moisture, heat, forced alignment that disallows movement, contaminants on the metal, such as grease, oil and rust, are all impediments to successful welds. Chemical elements contained in the steel may inhibit successful welding. Carbon levels, sulfur, phosphorus, and other elements may diminish your chances for a successful weld. In maintenance areas condition are seldom conducive to sound welding.
Certified, or very experienced welders will know what cautions to observe. Close this window and log in. Join Us Close. Are you an Engineering professional? Join Eng-Tips Forums! Join Us! By joining you are opting in to receive e-mail. Promoting, selling, recruiting, coursework and thesis posting is forbidden.
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Download Now. Weldments susceptible to cold cracking are required by the structural welding code AWS D1. This allows sufficient time for trapped hydrogen to diffuse out of the weld and heat affected zone. If no cracks are present 48 hours after welding the weldment is considered good.
To learn more about the causes and remedies for this type of cold cracking read Factors Influencing Hydrogen Induced Cracking. Many cracks that occur after the weld and heat affected zone have cooled down are not hydrogen induced cracks. Rather, they are cracks caused by weld discontinuities that created stress risers or reduced the effective area of the weld.
These cracks typically occur while the weldment or structure is already in service. This will be discussed in more detail in the coming weeks when we discuss the importance of crack location for root cause determination.
Proper inspection after welding is very important to prevent a discontinuity from creating problems. However, it is more important to have proper welding and fabricating procedures that prevent or limit susceptibility to discontinuities and defects.
And to reiterate, if you have a weld that cracks be sure to figure out why it did so you can prevent it from happening in the future. Welding Metallurgy and Weldability by John C. What type of inspection of the HAZ are you proposing? The cracks do not start or end in the weld metal they run parallel to it and they re outside the HAZ. They appeared about 4 or 5 days after the job was commissioned.
The pipe transports borehole water from the borehole to a tank at about 6 bar max. The welders are all good welders and these same welders have done lots of other jobs at our factory with very good results and continue to get good results on subsequent jobs. Does anyone have a similar experience that can shed some light? Your first line of your article mentions a truck axle.
We have been seeing a lot of axle failures and the axle company in central MO says they use a robot weld and it is not there fault. All failures have been the weld. All of the re-welded welds hold but they clam no responsibility and they note that they know what they doing.
By the looks of all failures they are clueless about welding. There are cracks on the top and the root of the weld is incomplete. The fusion to the axle is little to none. Again they state that it meets there expectations.
What do we do? A manufacturer that claims no responsibility for weld failures without proper investigation certainly sounds a bit fishy. Assuming that the axles are being used per the manufacturers specifications not exceeding limits or being misused , they should not fail.
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