Welding Category

Welding Stainless Steels

Grades of Stainless Steel

What is stainless steel? It is a kind of steel that also contains at least 12% chromium. Chromium forms a protective layer for the steel due to its oxidizing properties. It is a self-repairable coat.

However chromium is brittle and not too resistant to corrosive influences. When you increase chromium to 17%, that helps with corrosion resistance but it also makes it more brittle. To make the steel ductile, try adding 8% nickel. Now you've got 18/8 stainless steel (304). 316 / 316L has additional Molybdenum and higher Nickel which provides greater corrosion resistance.

The 18/8 stands for chromium and nickel content - 18/8 is 18%Cr and 8%Ni. For 3 numbers like 19/12/3 it is the Chromium, Nickel and Molybdenum content. 316L is 19%Cr, 12%Ni and 3%Mo.

Welding Stainless

There are 2 common grades of stainless: 304L (welded using 308L filler),

The welding equipment and machines are rated in accordance to the duty cycle they have, as commercial welders know. The duty cycle is often misunderstood and thus it this term has to be cleared. The duty cycle is based on a period of ten minutes.

When we have rated voltage, a power supply with a 100% duty cycle rating is in the position to operate without stopping at or below its rated current.

When we have a 50% duty cycle, this does not mean that the commercial welder will have a cycle to operate 50% of the time at rated voltage and current. In such cases it means that the welder can operate only 5 minutes on every 10 minutes at that voltage and that current.

This means that the welding equipment in such cases should be left idle five of every 10 minutes. The welding machines that are rated for a duty cycle of less than 100 % can be used without stopping by decreasing the current

1. Welding Processes Power Supply

Commercial welders are aware that the selection of a welding process to be used depends on and is determined by the characteristics of the joint, as well as the materials used including the design of the joint, the materials’ shape and thickness. The good commercial welder also knows that he has to consider the production requirements as well, including the rate and the quality.

After the welding process has been determined by the arc welder, that the proper power supply and welding equipment are chosen. In other words, it is the welding process that is the primary factor in the selection of the power supply that is to be used. In this article and in the ones that follow will be presented a guide concerning the power supplies for the welding processes that have been especially used in the past ten years.

The welding processes have once been considered as special, yet today they could be found in all spheres of m

The welding equipment and machines are rated in accordance to the duty cycle they have, as commercial welders know. The duty cycle is often misunderstood and thus it this term has to be cleared. The duty cycle is based on a period of ten minutes. When we have rated voltage, a power supply with a 100% duty cycle rating is in the position to operate without stopping at or below its rated current.

When we have a 50% duty cycle, this does not mean that the commercial welder will have a cycle to operate 50% of the time at rated voltage and current. In such cases it means that the welder can operate only 5 minutes on every 10 minutes at that voltage and that current. This means that the welding equipment in such cases should be left idle five of every 10 minutes. The welding machines that are rated for a duty cycle of less than 100 % can be used without stopping by decreasing the current rating.

Tig welders who are performing Tungsten Arc Welding are using inert shielding

Every time we weld on a piece of metal or even heat it up with a torch, the shape of the metal changes as we apply thermal energy or heat. The metal expands based upon a physical property called the coefficient of thermal expansion. This coefficient is different for each metal and is described in a unit that tells us how much the material grows per degree of temperature increase, or contracts when cooling. There are also other factors that contribute to distortion such that the temperature increase may remain localized "

Every time we weld on a piece of metal or even heat it up with a torch, the shape of the metal changes as we apply thermal energy or heat. The metal expands based upon a physical property called the coefficient of thermal expansion. This coefficient is different for each metal and is described in a unit that tells us how much the material grows per degree of temperature increase, or contracts when cooling.

There are also other

Skip welds or what some people call intermittent welds are a good tool to use in the right situation. Use of skip welds can reduce distortion, speed up production, reduce costs and reduce weight. Sometimes every lineal inch of joint need not be welded. Certain components or weld joints require 100 percent welding. When that is not the case, we might consider the use of skip welds. Skip welds are welds that are not completely welded the entire length. A segment of the joint is welded followed by a segment not welded. This alternating of welded and not welded segments continues along the joint as needed.

Skip welds are defined by a specific length of weld, and a pitch dimension. The pitch is defined as the center to center distance between the welded segments. Too often the pitch is mistakenly thought to be the length of the unwelded segment as opposed to the center to center distance between welds.

If we have to produce a full penetration weld

If the best of design is followed, joining thick to thin parts should be kept be to a minimum. When we do have to join thick to thin, we should follow some basic guidelines to be successful. The thicker part will always be able to absorb more heat than the thinner part. You should also consider the thermal conductivity of the materials and their effect on the welding process. Materials like aluminum can absorb much more heat than  something like steel, or stainless steel.

When welding something thick to thin, we need to make sure we have our amperage setting correct or we can risk burning the thinner of the two parts. If we set the amperage low to prevent excessive melting when welding, we risk not having enough heat to melt the ticker part. Also, if we set the amperage level too high to heat up the thicker part, we run the risk of burning or melting away the thinner part.

One approach is to use the correct amperage for the thinner material.

Depending upon the end-use or service conditions of the weld joint the welding engineer or designer may choose between an open or closed root. Closed roots occur when the adjacent members touch each other with no gap or space between the two. On the other hand,  the open root has a predefined gap or space. We call that space between the two joints the root opening.

The open root is usually used to join complete penetration joints between the welded members. When we think of penetration we usually think of how much the welding melted in or depth of bond between the two adjacent surfaces. The open root may also allow the backside of a joint to be welded from the front side. An example of this might be pipe that is joined to handle high-pressure, or high strength joints.

If adjacent members don't need to be completely welded through the full thickness or what we might call partial penetration, it may be acceptable to use a closed root opening. We

Just like that well warn pair of shoes, all of us have that special tool or piece of welding equipment that has some special meaning,some connection or attachment to our past. Sometimes that tool or equipment was also connected to a technology that has long ago been left in the dust, by newer ways, improved methods, different approaches or even newer technology.

Welding equipment, is just like the cars we drive. While that '57 Chevy, '66 Pontiac GTO or that '73 Olds Omega may get us to grandma's house and back, the gas mileage compared to the newest hybrid technology car will be vastly different. It will cost us more to maintain and get parts for our older car than a new one that is under warranty.

The same parallels exist with our welding power sources. That old red Tombstone you have converted into a bootleg TIG welder, or the blue buzz box from the flea market or garage sale, will make a bright light and get the metal hot, but sometimes when

Basic Fabrication Steps

Doesn't matter what we're planning to build there are some basic steps that we go through in the process of fabrication or welding up any metal fabricated object. The first step comes in determining the design, concept or shape of the unit we want to build or weld. Sometimes it is something unique that we have designed ourselves. More frequently in industry we have to build a part that conforms to a blueprint or technical drawing. It is from that drawing or sketch that we determine the steps necessary for fabrication.

How many of this part, or which part first and which part goes second or just some of the many steps we need to think about before we start. Many times the manufacturing traveler is developed to guide the fabrication steps. A good quality control program will require the use of it.

Once we have put together a plan on what we're going to do, we need to put together a list of tools,