Brazing and Soldering

Disadvantages of Braze Welding

- joints fail where subjected to intense heat, over 450*C - fail when subjected to alkali corrosion - poor choice where colour match is essential - poor choice where rigid joints are to be perfectly aligned

Advantages of Braze Welding

- where less heat is used, there is less warping or distortion - lower in residual stress - dissimilar metal can be joined - joints up to 60000 psi - some joint flexibility - only process acceptable for joining malleable cast iron

What size should tacks be?

1/4" in length

What size must the gap be?

1/8"

How far should the end of the cone be from the surface of the puddle?

3.2mm (1/8")

Inclination is expressed in degrees, so if you picture a clock face each five-minute division would represent how many degrees?

30ᵒ

What temperature does brass lose one half of its strength?

425*C

What size should the weld bead be?

5/16"

What is the melting point of BAg1?

607*C

What is the melting point of BAg3?

632*C

What is the melting point of BCuP-5?

641*C

What is the melting point of RBCuZn-C?

870*C

Carburizing Flame

A flame burning with an excess amount of fuel; also called a reducing flame, 2 1/2x

Who has developed specifications and classification systems for oxy-fuel, braze welding and fusion welding filler metals?

AWS

Which organization compiled specifications and developed classifications for oxy-fuel brazing, braze welding and fusion welding filler metals

AWS, classified on the basis of the mechanical properties of the deposited weld metal

While welding, you notice that one edge is melting away quicker than the other edge. What can you do to remedy this situation?

Adjust your torch angle

Seven Filler Metal Type Categories

BAg, BALSi, BNi, BCuP, BAu, BCo, BMg, the letter B designates the brazing process, E is for electrodes, R is for rods, RB indicates brazing filler metal, ex: BCup-1 indicates a specific chemical composition

Silver Filler Metals

BAg, used to join ferrous and non-ferrous metals except aluminum and magnesium, known as silver brazing alloys, temperatures range from 618*C to 1038*C

The Aluminum Association of America (AA) has written specifications for which group of filler metals?

BAlSi

What type of filler metal would be used where maximum resistance to oxidation and corrosion are required?

BAu

Which brazing filler metal would be used in the aerospace industry because it reacts minimally with base metals?

BAu

What is the AWS designation of the filler material with the trade name Sil-Fos®15?

BCuP-5

Which filler metal would be used primarily for 300-400 series stainless steel

BNi

Why can there be no universal flux?

Because of varying melting temperatures of filler metals and differing parent metal characteristics

Which process would you choose if warping or distortion of the base metal is of concern after the material is heated?

Braze welding

High amounts of silver in silver-copper brazing alloys do not wet out well while torch brazing, what is done to help overcome this problem?

Cadmium and zinc are added to the filler metal

What type of fumes can be toxic while brazing?

Cadmium fumes

What element is the most important alloying element in the manufacturing process of steel?

Carbon

What does the 1 indicate with the filler metal designation BCuP-1?

Chemical composition of the rod

Which piece of equipment restricts or prohibits the use of filler metal alloys containing Cadmium for brazing operations?

Commercial food equipment

Bronze is made by alloying what materials together?

Copper and Tin

Brass is made by alloying what materials together?

Copper and Zinc

While performing Oxy-fuel Welding, where do you add the filler metal?

Directly in front of the molten puddle

In what situation would one want to use less torch heat?

During vertical welding operations

What does tinning action refer to?

Flow of the brazing alloy over the heated surfaces

What should be removed from the brazed joint after it has been completed because of its corrosive properties?

Flux

Fluxing copper assemblies intended for use on refrigeration components is undesirable in many cases. Why?

Flux left in refrigeration assemblies may react with the refrigerant or cause blockage of lines or orifices

What is a problem encountered while using flux?

Flux residue is corrosive

The torch inclination should be between 5°-15°. Should you travel forehand or backhand?

Forehand

What is the term used to describe joint misalignment?

High-low

What would be the difference between braze welding and brazing?

In braze welding the filler metal is not distributed by capillary action

If your puddle is sluggish and you need to wait a long time for the metal to start to flow, what could you try to do to remedy the situation?

Increase your heat output

If a flux is required for the brazing operation, why is it important to flux the joint right after it is cleaned?

It can prevent the formation of oxides on the joint

What type of joints are preferred for brazing operations because they offer more surface area for the metal bonding to take place?

Lap joints

What can be done to prevent the assembly from sagging or moving during the heating and flowing cycle?

Maintain support for the joint during the cooling cycle to allow enough time for complete solidification

As you bring you torch closer to the work piece, what effect would this have on the puddle flow and penetration?

More penetration, narrower puddle

What could happen if you overheated the brazing joint before adding filler metal?

Oxidation

Impurities left behind in the joint area can result in adverse weld defects such as?

Porosity and/or lack of fusion

Where a high-quality joint is required, what is the rule?

Proper cleanliness that matches the type of material being prepared

What is the primary purpose of applying flux to all surfaces that will be brazed?

Protect the joint from oxidation during the heating and flowing process

Using the AWS Classification system, describe the R60 filler rod?

R = welding rod 60 = minimum as welded tensile strength of 60000 psi

According to the AWS A5.2 specification for Carbon and Low Alloy Steel Rods for oxy-fuel gas welding, what rod would you use if the weld procedure required post weld heat treatment?

R100

AWS A5.2 Four Major Classifications for Carbon and Low Alloy Steel Oxy-Fuel Gas Welding Rods for Fusion Welding

R45, R60, R65, R100

If you are looking for a filler rod for general purpose oxy-fuel welding, that possessed medium strength and good ductility, which rod would you choose?

R60

In order to achieve a proper butt joint fit-up, what is required?

Remove all high-low

What does the "R" indicate in the designation R100?

Rod

The filler metal designated BAg, would fall into which filler metal category?

Silver filler metals

What can happen if you use a grinder in the preparation of cast iron materials?

Smear free carbon

AWS A5.2

Specification for carbon and low alloy steel rods for oxy-fuel gas welding

What type of torch manipulation can help control weld puddle temperature?

Stepping action

What is the general rule when setting up Lap joints for welding?

The amount of overlap should equal the material thickness

The term Angle, when used in conjunction with welding operations, relates to what?

The angle formed between the heat source and the workpiece across the direction of travel

Why is clean metal important with brazing?

The filler metal will not flow through capillary action if the metal is not clean

The molten filler metal must Wet the base metal in order to achieve the proper metallic bond. This action is can be referred to as?

Tinning

One of the steps involved for a properly brazed joint, so you can ensure capillary action takes place, includes?

Using the recommended joint clearances for the brazing filler metal you are using

Braze welding would not be a satisfactory method of joining material together?

When the finished product operates at high temperatures

What is an important factor to take into consideration when selecting a filler rod for a given job?

Whether or not the selected filler metal will properly adhere to the base metal

What can have an affect on the weld profile and the depth of penetration?

Work Angle

Does the size of the Rod have any effect on the puddle during oxy-fuel welding

Yes, it needs to be large enough to chill the puddle, yet small enough to be melted quickly when added continually

What can be your best guide when selecting the right tip size and torch setting?

Your own Experience

BAg filler metal alloys, high in silver, do not wet out well when torch brazed. What is added to overcome this problem?

Zinc and Cadmium

What is an indication that the weld metal is penetrating through the full thickness of the joint?

a fluttering motion of the molten metal in the bottom of the keyhole

Paste Fluxes

act as a temperature indicator

In what positions can you use the R60 filler rod?

all positions

Steel

alloy of iron, carbon, manganese, phosphorus, sulphur and silicon with carbon being the most important alloying element

AA

aluminum association of america, written specifications for and classified aluminum and aluminum alloys, uses 4 digit system

AA 4047

aluminum brazing rod

BALSi

aluminum silicon filler metal

The bonding strength of a braze weld depends on the?

amount of properly tinned joint surface area

Metal

an element that is shiny and that conducts heat and electricity well

Tinning

another term for when the molten filler metal wets the base metal in order for a proper metallic bond to be created

What is proper procedure when joining metals of unequal thickness?

apply more heat to the thicker member to promote even heating

Why is there no universal flux for oxy-fuel welding?

because of the wide range of metal and filler metal melting temperatures and differing characteristics in weldable metals

Which welding type is not used for high temperatures?

braze welding

Element

cannot be broken down

Which type of flame is recommended with BALSi-4

carburizing flame

Which type flame is reccomended for manual torch brazing operations with silver based brazing filler metals?

carburizing flame, use of flux is essential

What happens when you grind to clean a surface?

cast iron contains carbon that is not dissolved within the iron itself, grinding leaves a smear of this free carbon on the surface, if not removed the carbon will cause voids along the joint surface

What happens if you don't remove flux residue

causes corrosion

Capillary Action

causes the liquid soldering or brazing maerial to flow throughout tight-fitting spaces, causes the allow to flow throughout the entire joint

What affects the size and shape of the weld profile and the depth of penetration?

changing the inclination

What affects the size of the weld and the penetration?

changing the travel speed

How to obtain maximum strength braze welds?

clean the joint surfaces,

BCo

cobalt filler metal

Gold Filler Metals (BAu)

composed of gold and copper, gold content can be high as 82%, used in electronics and aerospace inustries, do not alter the properties of thin base metals, used where maximum resistance to oxidation and corosion are required, flux is required for torch brazing

Aluminum Brazing Rod BALSi-4

contains 12% silicon, used only on aluminum and some of its alloys, results are good when used on 1050, 1100, 3003, 6063, 6061

Alloy Steel

contains all the elements found in steel, has additional elements to enhance mechanical or physical prperties

Nickel Filler Metals (BNi)

contains chromium and silicon, used where corrosion is a factor and low temperatures, used on 300-400 series SS and nickel-cobalt-based alloys, flux must be used for torch brazing

Brass

contains copper and zinc, 60% copper and 40% zinc

Bronze

copper and tin

BCuP

copper, copper-zinc and copper-phosphorus filler metal

How do you prevent oxidation?

cover surfaces with flux

Functions of Fluxes

deoxidation agents, cleansing agents, dislodges oxides and other impurities and float them to the surface, provide lubricating effect, form a protective slag layer over the weld

Forms of Oxy-Fuel Fluxes

dry powder, paste form or coated on the surface of the filler rod

Inclination on a Clock

each five-minute division on the clock face represents 30* of a circle

Methods to Remove Carbon Smear

eletrolytic salt bath, heating then using a wire brush, sandblasting, chipping with a pneumatic hammer, searing the joint surface with an oxidizing flame

How much overlap is normally used when preparing lap joints?

equal to the material thickness

AWS A5.2 Classifications

ex: R45, R = rod, two or three remaining digits designate the tensile strength in psi X 1000

Silver brazing alloys are suitable for high impact service?

false

Two different inclinations of oxy-fuel fusion welding are called?

forehand and backhand

Which welding type is used if a colour match is desired?

fusion welding

BAu

gold filler metal

What is the most common method of joint cleaning for the joining of steel, cast iron, and other ferrous metals

grinding

Alloy

has metallic chaacterisitics, made up of two or more elements, one must be metal

Cobalt Filler Metals (BCo)

have the highest service temperatures and used with cobalt alloys

What happens when you shorten the torch to work distance gap?

heat is concentrated, which increases depth of penetration while narrowing puddle flow

Backhand Inclination

heat source is pointed back at the puddle

R60

high carbon and manganese content, used for carbon steels with tensile strengths up to 410 MPa, used for low alloy steels, general purpose rod of medium strength and good ductilities, used for carbon steel pipes

What are brazing alloys not suitable for?

high impact service applications because they are soft

What can fluxes that flow at a low temperature not withstnd?

higher heats

What affects puddle flow and penetration

how close you hold the torch to the work

Inclination

inclination of the heat source in relation to the work piece when welding, expressed in degrees

What happens to flux that is left in regrigeration assemblies?

it may react with the refrigerant or cause blockage of lines or orifices

What does a filler rod need to be?

large enough to chill the puddle, yet small enough to melt quickly when added continously

R100

low alloy steel, intended for welding alloy steels that has a minimum tensile strength no higher than 690 MPa, respond to quenches

When fusion welding mild steel, you should use:

low carbon filler rod

R45

low carbon, used to join mild steel, general purpose rod, required tensile strength doesn't exceed 310 MPa

Brazing Filler Metal

low temperature brazing and silver soldering, can be used manually with an oxy-fuel torch or for fully automatic production line work, used in the joining of complex assemblies or dissimilar metals, or metals of different thicknesses

BMg

magnesium filler metal

Braze Welding FIller Metals

mainly brass, contains small amounts of tin, iron, manganese and silicon to minimize zinc vaporization and increase strength and hardness, applied manually using a oxy-fuel torch, orginally developed for repairing cracked or broken cast iron components

How to stop the assembly from sagging or moving out of alignment?

maintain support for the joint during the cooling cycle until the brazing alloy has had enough time to completely solidify

Beading

material is added by using a periodic dipping method rather than a constant feed method, add the rod from directly in front of the puddle

What two things happen when you dip the filler rod in the molten puddle?

material is added to the puddle, the puddle is cooled

Fusion

melting together of filler metal and base metal, or of base metal only to produce a weld

What kind of metals should be excluded from silver brazing?

metals that have a low melting point

RBCuZn-B

minumum tensile of 350 MPa, has a small amount of silicon to control zinc vaporization (fuming), used for braze welding of steel and cast iron and for resurfacing to build up wear surfaces and bearings

RBCuZn-C

minumum tensile of 350MPa, used for general purpose braze welding, popular general purpose braze welding rod

RBCuZn-D

minumum tensile of 410 MPa, has silicon added to reduce fuming

Uphill/Uphand

moving the plate to the vertical position and running some lines of fusion from bottom to top

Is there a relationship between tip size and rod size?

must match the filler rod to the tip size, filler rod needs to be large enough to chill the puddle and small enough to melt quickly

RBCuZn-A

naval brass, minumum tensile of (280 mpa) 40000 psi, used for braze welding of steel, cast iron and malleable cast iron, used for fusion welding of brass and for braze welding copper, bronze and nickel alloys

What kind of flame is used for braze welding?

neutral to slightly oxidizing flame

BNi

nickel filler metal

What will brass not stick to?

non-ferrous metals such as nickel and nickel alloys

Which metals is grinding avoided on?

non-ferrous metals, sanding with a non-metallic abrasive is used

How much space is normally left between plates fitted for a lap joint?

none

Does steel require flux?

not with oxyacetylene welding

Can aluminum bronze be silver brazed?

not without a special fluz for aluminum bronze is used

Can cast iron be silver brazed?

not without removing the silicon and carbon from the surfaces of the work

Forehand Inclination

point the heat source in the direction of the travel

How is capillary attraction and complete brazing alloy flow maintained?

proper alignment during the heating and flowing cycle

Carbon Steel and Low Alloy Steel Filler Rod Diameters

range from 1/16" to 1/4", rod length is 1m or 36"

What do you do if the puddle is very fluid and difficult to control?

reduce heat input

Why is it important to use clean metal for welding?

reduces the risk of defects in the weld such as porosity, slag inclusions, cracking

When preparing metal for braze welding, why would you radius corners and edges?

sharp edges tend to overheat and oxidize leading to a weaker joint

BAg

silver filler metals

AWS A5.8

specification for filler emtals for brazing and braze welding

AWS A5.31

specification for fluxes for brazing and braze welding

AWS A5.15

specification for welding electrodes and rods for cast iron

What helps control weld puddle temperature?

stepping action

General Rule when Setting up Lap Joints

the amount of overlap should equal the thickness of the material being welded

Angle

the angle that is formed between the heat source and the workpiece across the direction of travel, usually 1/2 the angle formed by the pieces making the joint

What happens to the keyhole as you add rod?

the keyhole should get smaller, keyhole should be in the centre of the gap

Base Metal

the metal or alloy that is welded, brazed, soldered or cut, known as base metal or parent metal

What happens when you increase the torch to work distance gap?

the puddle flow is wider and penetration is reduced

What is important when joining dissimilar metals that may have different thermal expansion rates?

the space between the joints must be maintained while heating

Explain why tack welds should be of good quality?

the tack welds become part of the finished weld

What occurs when the joint is properly aligned?

there is no high low

Why is silicon added to filler metals?

to lower the melting temperature of the filler metal

What does overheating result in?

total liquidation which causes pinholes or leaks

Braze welding tends to produce less residual stress and distortion?

true

It is advisable to match the filler metal to the parent metal whenver possible?

true

Aluminum Silicon Filler Metals (BALSi)

used to braze aluminum and aluminum alloys, flux must be used, joint clearances of 0.15mm to 0.25mm, preferred for lap joints where overlaps are less than 1/4", where overlaps more than 6.4mm, joint clearances up to 0.64mm are reccomended

Copper Phosphorus FIller Metals (BCuP)

used to join copper and copper alloys, should not be used on ferrous or nickel alloys or copper nickel alloys with a nickel content in excess of 10%, flux is reccomended, neutral to slightly reducing flame

Magnesium Filler Metals

used with magnsium alloys

Braze Welding

uses a filler metal that is liquid above 425*C, used in soldering and brazing, base metal is not metal and not distributed by capillary action

Brazing

uses liquid filler metals above 455*C, metal is distributed by capillary action, does not involve melting of the base metal, known as low temperature brazing and silver soldering

What do you do if the puddle is sluggish?

wait a long time for metal flow and increase heat input

When is flux not required

when brazing clean copper to copper

When is oxidization accelerated?

when heat is applied

Two signs of overheating when braze welding?

white flames are emitted, a blue flame appears around the puddle

Factors to Consider When Selecting a FIller Rod

will it adhere to the parent metal, will the heat used affect the finished dimensions, if its operating at high temperature or if a colour match is desired

Three Factors to be considered when selecting the type of filler rod for a given weld?

will the filler metal adhere, are the mechanical and physical properties, will the head used, is colour match, will the filler metal suit the purpose of the job

What forms are brazing filler metals available in?

wire, rod, powder, paste, washers, rings, strips, shims, slugs

Does copper brazing with other brazing alloys require flux?

yes

Does gray cast iron require flux?

yes

Is a gap between plates important when oxy-fuel welding square butt joints on 10 gauge carbon steel

yes, a gap allows heat from the torch to melt through the thickness of the metal, ensuring full penetration and fusion

What is your best guide to selecting the right size tip and torch setting?

your own experience

Silver copper alloys high in silver do not wet-out well when torched, how is this overcomed?

zinc and cadmium

Which alloys have toxic fumes?

zinc and cadmium

In general, what should be the torch angle while brazing?

½ of the joint angle