Chassis　lightweight　is　one　of　the　implementation　of　vehicle　lightweight,　the　use　of　Electric　Resistance　Welding(ERW)welded　pipe　by　bending　and　internal　high　pressure　molding　from　the　parts　are　an　important　part　of　the　chassis　components.　Due　to　the　limitation　of　welded　pipe　size,　thin　wall,　high　temperature　and　continuous　production,　the　conventional　nondestructive　testing　method　is　difficult　to　meet　the　continuous　dynamic　testing　requirements　of　ERW　welded　pipe.　In　view　of　the　small　defect　of　ERW　welded　pipe,　a　method　for　detection　of　welded　pipe　defects　based　on　the　principle　of　electromagnetic　induction　is　presented.　Firstly,　the　fuzzy　evaluation　model　of　weld　quality　was　established　based　on　the　fuzzy　mathematics　principle.　Secondly,　the　welding　mechanism　of　ERW　was　analyzed,　and　the　microstructure　of　the　weld　was　observed　by　metallographic　microscope,　and　the　microstructure　of　the　weld　was　obtained.　Finally,　eddy　current　method,　the　low-frequency　electromagnetic　scanning　method　and　magnetic　induction　method　were　used　to　detect　ERW　welded　pipes.　The　data　analysis　shows　that　the　magnetic　induction　method　can　realize　dynamic　detection　and　accurate　localization　of　welded　pipe　defects,　and　the　comprehensive　detection　effect　is　the　best.　©　Published　under　licence　by　IOP　Publishing　Ltd.